TCM - TOEO 2025

16:00 - 17:30

Registration

17:30 - 18:00

Welcome Addresses

Room 1: Megas Alexandros

18:00 - 18:40

PLENARY 1

Hideo Hosono

Chairs: George Kiriakidis and Vassilios Binas

Hideo Hosono

Chairs: George Kiriakidis and Vassilios Binas

18:00 - 18:40 Progress in Science and Application of Transparent Oxide Semiconductors Presenter: HIDEO HOSONO (Institute of Science Tokyo) View abstract Hide abstract Abstract: Two decades have passed since the first TCM conference. Transparent contact represented by ITO was only the major function for application before 2 decades. During the past 2 decades, distinct progress has been made both in science and application. The representative progress is seen in transparent oxide semiconductor in which Fermi level is controllable. Many n-type new materials are reported and carrier doping may be understood by computational approach For device application, oxide TFTs has grown to a hot topic in electronics. IGZO-TFTs are now widely used as the switching transistor of flat panel displays. Further oxide TFTs are attracting attention for memory application utilizing extremely low-off current.1,2 In his talk, I mainly introduce the progress in our research on transparent oxide semiconductors (Fig.1) along with current challenges:

18:40 - 19:20

PLENARY 2

Lars Österlund

Chairs: George Kiriakidis & Vassilios Binas

Lars Österlund

Chairs: George Kiriakidis & Vassilios Binas

18:40 - 19:20 ZnO interfaces: Defects, heterostructures and surface chemistry Presenter: Lars Österlund (The Ångström Laboratory, Uppsala University) View abstract Hide abstract Abstract: In many applications, such as electrodes and thin films in heterogeneous (photo/electro)catalysis, solid-state sensors, and batteries, the surface chemistry of ZnO is crucial. Defects are known to significantly influence the physicochemical properties of ZnO. Lattice vacancies and adsorbed surface species, originating from the synthesis, can modify and inhibit the intrinsic ZnO properties. Here, we present results on the interfacial properties of nanostructured ZnO prepared by commonly employed wet-chemical methods, providing molecular evidence of the role of defects and precursors on the ensuing surface chemical properties. We provide molecular evidence of two opposing effects on the catalytic activity that occur during heat-treatment of ZnO in oxidizing conditions: Reduction of site-inhibiting synthesis residues (increasing the reaction rate), and reduction of active lattice defect sites (decreasing the reaction rate). We show that by careful “engineering”, the ZnO interface can be purposefully adjusted to control which kind of defects that are exposed and remove unwanted synthesis residues.[1] Further, we show that by controlling the ZnO interface properties, Cu-Zn oxide heterojunction can be prepared by photo-decomposition of the chelated Cu(II) species [Cu(EDTA)]2+resulting in photocatalysts with markedly enhanced activity compared to corresponding Cu-Zn oxide structures containing a higher concentration of defects and synthesis residues.[2] The results are attributed to more efficient electron-hole separation in purposefully synthesized Cu2O@ZnO due to well-developed interfaces. Our results show the importance of careful synthesis and pre-treatment methods to prepare ZnO materials with desired interfacial properties for catalytic and optoelectronic applications

19:30 - 20:30

Welcome Reception

Room 1: Megas Alexandros

Room 2: Achilles

09:00 - 09:40

PLENARY 3

Andreas Klein

Chair: HIDEO HOSONO

09:00 - 09:40 Analyzing defect properties in oxides by x-ray photoelectron spectroscopy Presenter: Andreas Klein (Technical University of Darmstadt) View abstract Hide abstract Abstract: Defects and dopants are the key to understand and manipulate the properties of functional ceramics. Despite their importance, the knowledge about defect properties is mostly qualitative and based on separate concepts for the different possible charge compensation mechanisms. A combined quantitative treatment of the different charge compensation mechanisms is highly desirable and could pave the way for predicting material properties. Quantitative information on defect properties, such as their energy levels which determine the valence state, can directly be used for quantitative defect models but are still barely available from experiment. X-ray photoelectron spectroscopy (XPS) has the potential to fill this gap, as it provides simultaneous information on the valence states and on the position of the Fermi energy, which are intimately connected with each other. The technique is able to directly determine charge transition levels of dopants without any assumptions and model comparison and can be applied to doping concentrations even below 1%. As XPS is element specific, it can also be applied to materials in which more than a single dopant species is present. The presentation will give an overview on how defect properties can be analyzed with XPS. Experimental solutions for the challenge of measuring highly insulating samples will be demonstrated with examples from electronic, ionic and mixed ionic-electronic conductors and piezoelectric materials. The extend to which defect energy levels depend on concentration and the possibility to transfer defect energy levels between materials will be discussed. For some cases, the experimentally obtained defect properties will be compared with those calculated by means of density functional theory.

09:40 - 10:20

PLENARY 4

Gunnar Westin

Chair: HIDEO HOSONO

09:40 - 10:20 Complex structure and composition metal-oxides through solution processing Presenter: Gunnar Westin (Uppsala University) View abstract Hide abstract Abstract: Metal-organic solution processing offers efficient routes to complex structure and composition metal-oxides of high quality including nano-particles, nano-sponges, and thin- and ultra-thin films. A wide range of analytical techniques allows elucidating the reaction steps from precursors to the target oxide in details, including the dopant metal-ion distribution, oxidation state and coordination.

10:20 - 10:50

COFFE BREAK

10:50 - 11:20

I1

Daniel Bellet

Chair: Andreas Klein (Technical University of Darmstadt)

10:50 - 11:20 Brief overview of metallic nanowire based transparent conductive materials Presenter: Daniel Bellet (Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, 38000 Grenoble, France) View abstract Hide abstract Abstract: Transparent electrodes (TE) play a pivotal role within numerous devices in optoelectronic or energy areas. This concerns for instance devices such as solar cells, light-emitting devices, touch screens, transparent heaters, low-emissivity films or smart windows. TE should exhibit high optical transmittance and low sheet resistance, as the two prevailing properties. However other characteristics appear also significant depending on applications; this concerns for instance optical haziness or mechanical flexibility. Transparent conductive oxides (TCO) have been studied for several decades, and are the most commonly used TE in industrial devices. Among them, indium tin oxide (ITO) films are the most common TE materials used by industry due to their good optical and electrical properties, while aluminum doped Zn oxide (AZO) or fluor-doped tin oxide (FTO) exhibit also good potential. TCO have been deeply investigated and optimized, however TCO are brittle and could be expensive. The development of next generations of optoelectronic devices needs TE that exhibit good optical and electrical properties, good flexibility and moreover their fabrication has to be compatible with high-throughput fabrication for industrial applications (roll-to-roll for instance) and low cost. Several emerging TE have been investigated with this aim: this includes carbon nanomaterials, conductive polymers and metallic nanostructures.[1,2] Among the latter, metallic nanowire (MNW) networks have received intensive research interest thanks to their high electrical conductivity, optical transparency in visible and near infrared regions and excellent flexibility performances[3,4]. Such TE consist of a network of randomly oriented and interconnected MNW (so far mainly silver nanowires) deposited on a transparent substrate. While such TE exhibit very good electrical and optical properties, morphological instabilities induced by thermal or electrical stress and high surface roughness constitute the main bottlenecks for further long-term operating performance[5]. Metal oxide layers are shown as a promising protective overcoat around nanowires with encouraging results in terms of stability enhancement as well as flatness improving capability as compared to bare nanowires[6]. The nature of the metal oxides (such as SnO2, Al2O3, TiO2 and ZnO…) and how they affect concrete device performance is an aspect to be investigated for each application in order to tune and design more efficient device structures[6]. Main research works have dealt with the influence of MNW chemical nature and dimensions, network density, post-deposition treatment on the main properties of MNW networks. As the investigation of MNW based nanocomposites that can exhibit enhanced properties and/or stability has also been the subject of many studies[7]. The aim of this presentation is to give an overview of the main features related to MNW networks intensive research activities, including both fundamental and applicative aspects. The associated assets and drawbacks of MNW networks, as well as the challenges and opportunities, will be presented and discussed. Associated references: [1] V. H. Nguyen, D. T. Papanastasiou, J. Resende, L. Bardet, T. Sannicolo, C. Jiménez, D. Muñoz‐Rojas, N. D. Nguyen, D. Bellet, Small 2022, 2106006. [2] X. Lu, Y. Zhang, Z. Zheng, Adv. Electron. Mater. 2021, 7, 2001121. [3] T. Sannicolo, M. Lagrange, A. Cabos, C. Celle, J.-P. Simonato, D. Bellet, Small 2016, 12, 6052. [4] D. Tan, C. Jiang, Q. Li, S. Bi, J. Song, J Mater Sci: Mater Electron 2020, 31, 15669. [5] J. J. Patil, W. H. Chae, A. Trebach, K. Carter, E. Lee, T. Sannicolo, J. C. Grossman, Adv. Mater. 2021, 33, 2004356. [6] A. Sekkat, C. Sanchez-Velasquez, L. Bardet, M. Weber, C. Jiménez, D. Bellet, D. Muñoz-Rojas, V. H. Nguyen, J. Mater. Chem. A 2024, 12, 25600. [7] L. Bardet, M. Akbari, C. Crivello, L. Rapenne, M. Weber, V. H. Nguyen, C. Jiménez, D. Muñoz-Rojas, A. Denneulin, D. Bellet, ACS Appl. Nano Mater. 2023, 6, 15234.

I2

Juris Purans

Chair: Emmanouil Gagaoudakis (IESL, FORTH)

10:50 - 11:20 Adaptive Chromogenic Material for Smart Windows Presenter: Juris Purans (Institute of Solid State Physics University of Latvia) View abstract Hide abstract Abstract: The growing prevalence of glass facades and large windows in modern architecture drives the demand for energy-efficient building solutions. Smart windows utilizing chromogenic materials—electrochromic, thermochromic, and photochromic thin films—offer a promising approach by regulating light and heat transmission. Within the EU HORIZON project Smart Windows for Zero Energy Buildings, advanced transition metal oxide coatings, including WO₃, NiO, and rare-earth oxyhydrides (Y-O-H), have been developed using scalable deposition techniques such as reactive magnetron sputtering and roll-to-roll processing. Extensive synchrotron-based and complementary analytical studies at ISSP LU have deepened understanding of these materials. Notably, the discovery of rare-earth oxohydrates (REOH) with light-induced resistivity changes has opened new directions for multifunctional applications, including antibacterial transparent conductive coatings. This research highlights the transformative potential of chromogenic materials in advancing zero-energy building technologies.

11:20 - 11:50

I3

Dimitrios Koutsouras

Chair: Andreas Klein (Technical University of Darmstadt)

11:20 - 11:50 Organic materials for bioelectronic devices Presenter: Dimitrios Koutsouras (University of Bath) View abstract Hide abstract Abstract: Bioelectronics is the emerging interdisciplinary field that integrates biology with electronic systems to revolutionize the way we diagnose and treat disease. Its origins can be traced back to the 18th century, when Luigi Galvani’s experiments with detached twitching frog legs revealed the nature of electricity in living organisms. Today, this legacy continues in a plethora of bioelectronic devices which include defibrillators and pacemakers to prevent or correct arrhythmias, cochlear implants to provide the sense of hearing, and glucose monitoring devices to help diabetics manage their disease. However, the coupling between biology and electronics is limited by the materials that can form stable interfaces with the tissue and transduce signals across the biotic/abiotic ensemble. Recently, organic electronic materials have emerged as a promising solution. These materials offer their unique properties, which include mixed ionic/electronic conductivity, mechanical flexibility and enhanced biocompatibility, and which make them ideal for interfacing biological systems.

I4

Jiří Rezek

Chair: Emmanouil Gagaoudakis (IESL, FORTH)

11:20 - 11:50 High-power impulse magnetron sputtering as a knob for tailoring transparent conductive oxides Presenter: Jiří Rezek (University of West Bohemia in Pilsen) View abstract Hide abstract Abstract: Transparent conductive oxides (TCOs) are crucial for energy self-sufficiency and sustainability, as they uniquely combine electrical conductivity with optical transparency—but this duality demands precise control of their composition and structure. High-power impulse magnetron sputtering (HiPIMS) uses pulsed energy to reach target power densities up to a thousand times higher than conventional dc sputtering, enabling fine tuning of the energy delivered to the growing film—and thus its crystallinity and other properties—by varying discharge parameters (pulse length, power density, etc.). Moreover, HiPIMS can alter a layer’s elemental composition from a compound target without changing the target itself. In this presentation, we demonstrate successful HiPIMS deposition of several TCOs—IGZO, AZO, WOₓ, V₁₋ₓWₓO₂ and Cu₂O.

11:50 - 12:50

O1-3

                                                        Chair: 

Andreas Klein (Technical University of Darmstadt)

11:50 - 12:10 From Crystal Symmetry to Heat Flow: Resolving Anisotropic Transport in Gallium Oxide Phases Presenter: Markus Wagner (Paul-Drude-Institute, Berlin, Germany) View abstract Hide abstract Abstract: We present a comprehensive, contactless investigation into the anisotropic phonon-governed properties of the ultra-wide bandgap semiconductor gallium oxide, with a focus on both nanoscale phonon dynamics and nanoscale thermal transport phenomena. We employ a suite of complementary, all-optical spectroscopic techniques to map phonon behavior over multiple frequency and length scales and provide guidelines for the optimization of heat flow in the low symmetry transparent metal-oxide Ga2O3.
12:10 - 12:30 Industry-Scaled DC Sputtering of SnZnOx: Toward Indium-Free Transparent Electrodes for Solar Cells Presenter: Marlene Härtel (Helmholtz-Zentrum Berlin) View abstract Hide abstract Abstract: Transparent conductive oxides are used in many optoelectrical devices, such as solar cells or light-emitting diodes. Often, these devices require TCOs to be deposited at low temperatures without compromising their excellent optoelectrical properties, which limits the selection of suitable materials. Therefore, the most widely used TCOs are indium-based. However, indium’s scarcity and increasing demand for optoelectronic devices will lead to supply challenges and rising costs. This study investigates tin-zinc oxide (SnZnOx) as an indium-free alternative, deposited via in-line DC sputtering. By adjusting oxygen content, apply substrate heating during the sputter rpocess, and post-deposition annealing, a minimum resistivity of 1.59 mΩcm was achieved. Though higher than conventional ITO/IZO, this DC sputter deposited SnZnOx shows strong potential as a sustainable TCO candidate.
12:30 - 12:50 Revealing the incorporation sites and local structure of nickel and selenium in doped copper iodide thin films Presenter: Mustafa Göktürk Yazlak (Leipzig University) View abstract Hide abstract Abstract: Copper iodide (CuI) is a promising p-type semiconductor for transparent electronic applications such as solar cells, flat panel displays, and LEDs. The electrical properties of CuI can be tailored by substituting it, for example, with nickel (Ni) or selenium (Se) [1,2], yet the specific incorporation sites and mechanisms of these elements within the CuI matrix are not fully understood. This study presents an investigation of polycrystalline CuI thin films with varying selenium and nickel concentrations, deposited by pulsed laser deposition (PLD) and reactive co-sputtering on glass substrates[3]. CuI:Ni thin films (1–30 at% Ni) and CuI:Se thin films (0.4–3.8 at% Se) were prepared and capped with 150 nm and 200 nm Al₂O₃ layers, respectively, to prevent oxidation. X-ray Absorption Spectroscopy (XAS) was performed at ~10 K at the Cu, Se, and Ni K-edges to investigate the local structure of Ni and Se in the CuI matrix. For the CuI:Ni thin films, the near edge structure and the extended X-ray absorption fine structure (EXAFS) at the Cu K-edge indicate potential copper oxidation[4]. These effects diminish with increasing Ni concentration. Preliminary results from Ni K-edge EXAFS analysis reveal that Ni is coordinated by both I and O atoms, indicating different bonding environments. This is supported by microstructural studies, which show phase separation and the formation of secondary Ni-containing phases, such as NiI2 and NiI2(H2O)6, especially at high Ni content[3]. These secondary phases complicate the interpretation of the Ni local structure, and further detailed EXAFS analysis at the Ni K-edge is currently underway to clarify these findings. For the CuI:Se thin films, EXAFS fitting at the Cu K-edge reveals only a slight increase in the Cu–I bond length with increasing Se content, suggesting that Se doping up to 3.8 at% induces only minor changes in the local Cu environment. EXAFS analysis at the Se K-edge shows that Se atoms are predominantly coordinated by Cu, with no evidence of Se–Se bonding. The Se–Cu bond lengths remain nearly constant across doping levels, and structural disorder is low. These findings indicate that at the studied low concentrations, selenium incorporates uniformly, most likely substituting copper on lattice sites without significantly disrupting the CuI structure. Overall, these results highlight the contrasting behavior of the two dopants: while selenium has minimal structural impact at low concentrations, nickel appears to oxidize at low doping levels and potentially forms secondary phases at the higher concentrations. [1] P. Storm et al., Phys. Stat. Sol. RRL 15,2100214 (2021) (doi:10.1002/pssr.202100214). [2] A. Annadi et al., ACS Appl. Mater. & Interf. 12, 6048 (2020) (doi:10.1021/acsami.9b19550). [3] C. Dethloff et al., Phys. Status Solidi B, 261: 2300492 (2024) (doi:10.1002/pssb.202300492) [4] E. M. Zollner et al., Phys. Status Solidi A, 220: 2200646 (2023) (doi:10.1002/pssa.202200646).

O4-6

Jorgen Sweelssen

Chair: Emmanouil Gagaoudakis (IESL, FORTH)

11:50 - 12:10 Tailored liquid-phase chemistry to achieve low-temperature synthesis of BiVO4 for photoelectrochemical water splitting Presenter: Jorgen Sweelssen (TNO) View abstract Hide abstract Abstract: In order to reduce reliance on fossil energy sources, photo-electrochemical water splitting (PEC) can play a key role in bringing down the price of green hydrogen. BiVO4 is a well known material for this application, but impact is limited by synthesis and processing constraints related to temperature and solvent requirements. This this study, both aspects are addressed in order to increase the applicability of this promising PEC material.
12:10 - 12:30 Triode Plasma Approach to Low-Damage TCO Deposition for Silicon Heterojunction Solar Cells Presenter: Joon-Ho Oh (Korea Institute of Energy Research) View abstract Hide abstract Abstract: Transparent conducting oxides (TCOs) are essential in various optoelectronic applications, including carrier-selective passivating contact solar cells, due to their excellent transparency and electrical conductivity. However, conventional diode-configured sputtering methods often introduce significant sputter damage, which degrades the surface passivation quality of a-Si:H/c-Si silicon heterojunction (SHJ) solar cells. This degradation is primarily caused by the bombardment of highly energetic oxygen ions, resulting in partially irreversible damage even after thermal annealing. In this presentation, we propose a triode plasma sputtering configuration that integrates a negatively biased mesh electrode into the conventional diode system. Measurements showed that sputter damage in SHJ devices can be assessed by observing the evolution of implied open-circuit voltage (iVoc), effective carrier lifetime (τeff), and low-temperature hydrogen exodiffusion in SHJ precursor structures. Our triode plasma approach suppresses oxygen ion bombardment, reducing τeff degradation from 96% (diode) to just 7% (triode). We also observed that triode-configured plasma not only reduced sputter damage but also altered the properties of as-deposited ITO films, which serve as indicators of this reduction. The triode configuration not only minimizes oxygen ion damage but also yields ITO films with enhanced carrier mobility, higher refractive indices, and lower extinction coefficients. Furthermore, the reduction in ion bombardment is reflected in a shift in the preferred crystal orientation of the ITO films from the (400) to the (222) plane.
12:30 - 12:50 Low-resistivity of highly nitrogen-doped p-type Cu2O thin films prepared by reactive HiPIMS Presenter: Jan Koloros (University of West Bohemia in Pilsen) View abstract Hide abstract Abstract: In our work, we systematically investigated the role of nitrogen incorporated in Cu2O thin films, mainly on optical and electrical properties, namely optical band gap and electrical resistivity. The Cu2O:N films were prepared by reactive HiPIMS of Cu circular target (100 mm in diameter) in Ar+O2+N2 atmosphere. The prepared p-type Cu2O:N films with the highest value of a nitrogen fraction of 90% exhibited very low resistivity about 5×10^(-2) Ωcm exceeding current state of the art.

12:50 - 14:50

LUNCH BREAK + POSTER SESSION I

14:50 - 15:30

PLENARY 5

Sanjay Mathur

Chair: Lars Österlund

14:50 - 15:30 Magnetically Tailored Metal Oxide Thin Films as Efficient Catalysts for Green H₂ and NH₃ Synthesis Presenter: Sanjay Mathur (University of Cologne, Germany) View abstract Hide abstract Abstract: Thin films of semiconductor oxides offer tunable electronic properties and high surface-area interfaces, making them ideal platforms for efficient small molecule activation in green hydrogen and ammonia production. The growing possibilities of engineering nanostructures in various compositions (pure, doped, composites, heterostructures) and forms has intensified the research on the integration of different functional material units in a single architecture to obtain new photo- and electrocatalytic materials. We report here on the influence of external magnetic fields applied parallel or perpendicular to the substrate during plasma enhanced chemical vapor deposition of transition metal oxides. Films grown from transition metal precursors showed pronounced changes in crystallographic textures depending upon whether CVD was performed with or without external magnetic field. Investigations on the water splitting properties of the hematite films in a photoelectrochemical reactor revealed superior photocurrent values of hematite photoanodes deposited in external magnetic field. This talk will demonstrate that applying magnetic fields during growth of thin films can fundamentally reconfigure lattice characteristics. This is manifested in the alteration of their crystallographic structure and the topology of the surface states. This dual modulation precisely tailors their intrinsic and emergent electrochemical properties. The MF-CVD approach establishes a groundbreaking and versatile strategy to transform functional materials at the atomic level.

15:30 - 16:10

PLENARY 6

Bernd Szyszka

Chair: Lars Österlund

15:30 - 16:10 Activation of thin film growth versus plasma damage – the challenge in sputtering of transparent conductors and active semiconductive coatings Presenter: Bernd Szyszka (Technische Universität Berlin) View abstract Hide abstract Abstract: Sputter deposition of TCOs, ASOs and dielectrics must match the balance between activation of thin film growth and plasma damage to obtain the materials performance necessary. In this paper, we review the current state of technology and we discuss a novel method, the pulsed reactive hollow cathode gas flow sputtering which has the potential to overcome the limitations of the established technologies.

16:10 - 16:40

COFFE BREAK

16:40 - 17:20

PLENARY 7

Darrell Schlom

Chair: Sanjay Mathur

16:40 - 17:20 Reaching beyond Diamond to Sapphire, a 7 eV Semiconductor Presenter: Darrell Schlom (Cornell University, USA) View abstract Hide abstract Abstract: We report Si-doped α-(AlxGa1–x)2O3 with the sapphire structure and a bandgap exceeding 7 eV synthesized by suboxide MBE (S-MBE). In S-MBE, pre-oxidized molecular beams of the constituents, i.e., Ga2O and SiO for the growth of Si-doped α-(AlxGa1–x)2O3, are supplied. Providing a suboxide molecular beam bypasses the rate-limiting first step of the two-step reaction mechanism involved in the growth of α-Ga2O3 by conventional MBE.

17:20 - 18:00

PLENARY 8

Panos Patsalas

Chair: Sanjay Mathur

17:20 - 18:00 Laser growth and processing of materials in the nanotechnology era View abstract Hide abstract Abstract: Laser growth and processing of materials in the nanotechnology era

18:00 - 18:30

I5

József S. Pap

Chair: Bernd Szyszka (Technische Universität Berlin)

18:00 - 18:30 Benchmarking Membrane Electrode Assembly Inks with Transparent Conductive Oxides for Proton-Exchange Membrane Water Electrolysis Presenter: József S. Pap (HUN-REN Centre for Energy Research) View abstract Hide abstract Abstract: A central challenge in solar hydrogen production is replacing noble metal catalysts in water electrolyzers and photoelectrocatalytic systems with non-noble metal alternatives. However, non-noble metal catalysts are prone to degradation and typically demand a support for prolonged operation. Doped TCOs offer good conductivity as support, but corrosion may complicate stability. Recently, we began investigating TCOs as ink constituents for membrane electrode assembly fabrication in proton-exchange membrane single water electrolysis cells. Developing such ink compositions is a complex and laborious optimization challenge. We utilize commercial, uniform FTO-, ITO-, and ATO-coated support electrodes to study the potential-dependent behavior and interaction with ink components like Nafion and various Fe- and Ni-containing molecular pre-catalysts before their incorporation into MEA inks.

I6

Nikolaos Pliatsikas

Chair: Panagiotis Patsalas (Aristotle University of Thessaloniki)

18:00 - 18:30 Laser processes for Colloidal Conductive Metal Nitrides View abstract Hide abstract Abstract: Laser processes for Colloidal Conductive Metal Nitrides

18:30 - 19:50

O7-9

                                                        Chair: 

Bernd Szyszka (Technische Universität Berlin)

18:30 - 18:50 Real time optical observation of multi-filament formation and electrode remodeling in Ag/SiO2/Au memristors Presenter: Varun Ranade (Trinity College Dublin) View abstract Hide abstract Abstract: We report the direct optical observation of resistive switching mechanisms in Ag/SiO₂/Au memristive devices using in-situ microscopy during electrical characterization. Our findings reveal multiple critical current thresholds that separate standard memristive behaviour (volatile and non-volatile) to permanent electrode remodelling. Unlike conventional filamentary switching, which occurs at nanoscale dimensions[1,2], we demonstrate that increasing compliance currents from 0.5μA to 50mA triggers the formation of multiple micron-sized filamentary structures visible under standard optical microscopy. These structures appear precisely coincident with the high-to-low resistance state transitions. Differential interference contrast microscopy reveals both Ag extrusions and corresponding voids, confirming a substantial material redistribution process. AFM measurements verify these features as physical Ag protrusions extending from the electrode surface. Notably, the controlled formation of multiple parallel filaments and high current handling capability (up to 70mA) suggest applications beyond conventional memristors, including reconfigurable RF circuit elements, high-power switching, and plasmonic devices. The dependence of filament distribution on device geometry provides pathways for engineering application specific conduction patterns. This work bridges the gap between resistive switching mechanisms and microscale material transport phenomena with a rare direct visualization, enabling potential applications in optically accessible memory elements where states can be read both electrically and optically, advancing hybrid electro-optical computing architectures[3] and robust neuromorphic systems for high-power environments. References: [1] Yang, Y., Gao, P., Gaba, S. et al. Observation of conducting filament growth in nanoscale resistive memories. Nat Commun 3, 732 (2012). [2] Krishnan, K., Aono, A., Tsuruoka, T. Kinetic factors determining the conducting filament in solid polymer electrolyte based planar devices. Nanoscale, 2016, 8, 13976-13984 [3] Cheng, B., Zellweger, T., Malchow, K. et al. Atomic scale memristive photon source. Light Sci Appl 11, 78 (2022).
18:50 - 19:10 A REJUVENATION STUDY OF WO3 AND Re:WO3: THIN FILMS DEPOSITED ON FTO SUBSTRATE USING ULTRASONIC SPRAY PYROLYSIS Presenter: Dwight Acosta (Instituto de Fisica, National Autonomus University of Mexico) View abstract Hide abstract Abstract: Rheniun doped WO3 thin films were deposited by spray pyrolysis. The samples were under cyclic voltammetry runs in order to induce changes in electrochromic properties.After 5000 cycles of extraction and injection of ions the the samples lost a 90% of transparency, then were under rejuvenation processes and WO3 recovered its transparency and its electrochromic properties
19:10 - 19:30 Sputter deposited CuO-WO3 Nanosized Heterojunctions for Gas Detection Presenter: Nirmal Kumar (University of West Bohemia in Pilsen) View abstract Hide abstract Abstract: In this study, we explore the synthesis of nanostructured Metal-Oxide Semiconductor (MOS) system of cupric oxide (CuO NPs) and tungsten oxide (WO3) films, subsequently utilized as conductometric gas sensors. Nanoparticles of CuO were synthesized using a magnetron-based gas aggregation nanoparticle source (GAN) and deposited on and beneath transparent ultra-thin films of (WO3). During high-temperature stabilization for gas sensing measurements, interfacial reactions between CuO nanoparticles and WO₃ led to the formation of copper tungstate (CuWO₄), creating a multi-component heterostructure. The gas sensing performance of the CuO-WO₃ system was evaluated under varied operational conditions. The composite exhibited enhanced sensitivity, selectivity, and stability compared to individual components, attributed to synergistic interactions at the nanoscale. Key metrics such as response/recovery times and humidity tolerance were systematically analyzed, with optimal samples demonstrating rapid response dynamics and robust performance under humid environments. Selectivity studies revealed preferential sensitivity toward acetone, suggesting tunability for practical applications. Material characterization via SEM confirmed the uniform distribution of CuO nanoparticles (20–50 nm) embedded within the WO₃ matrix. XRD and Raman spectroscopy validated the coexistence of CuO, WO₃, and CuWO₄ phases. The improved sensing mechanism is ascribed to the formation of nanosized heterojunctions at CuO/WO₃ and CuWO4/WO3 interfaces and charge carrier modulation via CuWO₄, which amplifies conductivity changes upon gas adsorption. These findings highlight the potential of engineered heterostructures in advancing gas sensor technology, offering a pathway for designing high-performance, multi-functional sensing platforms through controlled nanoscale integration. Further optimization of composition and interfacial engineering could enable tailored responses for environmental monitoring and industrial safety systems.

O10-12

                                                        Chair: 

Panagiotis Patsalas (Aristotle University of Thessaloniki)

18:30 - 18:50 Development of a synthesis route for YScS3, a potential sulfide p-type TCM Presenter: Eleanor Teather (University College London) View abstract Hide abstract Abstract: Within novel transparent conducting materials (TCMs), developing a high-quality p-type remains elusive. Until recently, oxides have primarily been explored for TCMs, because their chemistry is well understood and they are affordable and relatively easy to synthesise. However, oxide p-types consistently show low conductivity[1]. This has been attributed to the high electronegativity of oxygen ‘trapping’ holes around the oxide ions, leading to a high hole effective mass. Other chalcogenide anions offer an alternative, having lower electronegativity while retaining similar bonding behaviour. This approach has seen some success, with reports of conductivities up to 1000 S cm-1 for sulfide TCMs, compared with approximately 400 S cm-1 for oxides[1]. However, these are not yet comparable to n-types, so further research is necessary. One challenge is that non-oxide materials can be difficult to synthesise, impeding their development. In 2020 Zhang et al.[2] predicted Zn-doped YScS3 as a good p-type TCM, with a low calculated hole effective mass of 0.48 m0, comparable to the electron effective mass of ITO[3]. YScS3 has previously been synthesised[4], but its properties were not studied. We have developed new methods to synthesise YScS3. Powders have been synthesised by conversion of the oxides under CS2 gas, from which pure single crystals were grown by chemical vapour transport. Zn-doped powders have been synthesised in a two-step method, with Sc-deficient powders formed under CS2, followed by incorporation of Zn in a sealed tube. This will enable YScS3 to be assessed as a TCM. Moreover, optimizing the synthesis of YScS3 provides insights for producing other novel sulfide TCMs. References [1] S. K. Maurya et al., Energies, 15, 8698, 2022 [2] H. Zhang et al., Chinese Physics Letters, 37(9), 097201, 2020 [3] S. F. J. Blair et al., Nanomaterials, 13(13), Art. no. 13, 2023 [4] N. Rodier et al., Comptes rendus hebdomadaires des séances de l’Académie des sciences, Série C, 270, 2127, 1970
18:50 - 19:10 Insight into the morphological instability of metallic nanowires under thermal stress Presenter: François Balty (ULiège) View abstract Hide abstract Abstract: Silver nanowires (AgNWs) are key components in emerging transparent conductive materials, offering a scalable, flexible, and high-performance alternative to brittle oxide-based conductors. Yet, their long-term stability remains a critical concern. It is well known that, under thermal stress, AgNWs spontaneously fragment into periodic chains of nanospheres, even at temperature more than 600°C below the bulk melting point of silver. This degradation mechanism drastically reduces network conductivity. This instability has often been described by analogy with the Plateau–Rayleigh instability of liquid jets [1]. However, this fluid-based framework fails to quantitatively match experimental observations in solid-state nanowires [2]. In this work, we revisit the origin of this phenomenon using a solid-state diffusion model initially proposed by McCallum et al. [3], which considers curvature-driven mass transport in a solid “line of thin film” resting on a substrate, an approach that motivated this work. High-resolution electron microscopy is used to monitor the thermal evolution of nanowires with varying diameters, and statistical analysis of the resulting breakup wavelengths is compared to both Rayleigh’s predictions and the solid-state model of McCallum et al. These findings refine our understanding of how nanowire morphology evolves under heat and provide a theoretical basis for temperature-induced failure in AgNW networks [4]. By identifying the relevant physical mechanism underlying thermal degradation, this work contributes to the design of more stable and reliable transparent conductors for optoelectronic devices operating under demanding conditions. [1] L. Rayleigh, On the instability of jets, Proc. Lond. Math. Soc. s1–10 (1) (1878) 4–13. [2] D.P. Langley, M. Lagrange, G. Giusti, C. Jiménez, Y. Bréchet, N.D. Nguyen, D. Bellet, Metallic nanowire networks: effects of thermal annealing on electrical resistance, Nanoscale 6 (2014) 13535–13543. [3] M.S. McCallum, P.W. Voorhees, M.J. Miksis, S.H. Davis, H. Wong, Capillary instabilities in solid thin films: lines, J. Appl. Phys. 79 (10) (1996) 7604–7611. [4] F. Balty, A. Baret, A.V. Silhanek, N.D. Nguyen, Insight into the morphological instability of metallic nanowires under thermal stress, JCIS 673 (2024) 574-582.
19:10 - 19:30 Cation Engineering and Quantum Effects in Zinc Tin Oxide Films Presenter: Ainur Zhussupbekova (Trinity College Dublin) View abstract Hide abstract Abstract: Amorphous zinc tin oxide (a-ZTO) has emerged as a promising candidate among transparent conducting oxides (TCOs) due to its excellent optical transparency, controllable charge carrier concentration, and the use of earth-abundant elements. To optimize its performance for applications in transparent electronics, it is essential to understand the correlation between its local bonding environment and its macroscopic electronic properties. In this work, we investigate the structural and electronic characteristics of a-ZTO thin films fabricated via magnetron sputtering and spray pyrolysis, with a particular focus on how variations in the Zn:Sn cation ratio influence material behaviour. Using a combination of X-ray absorption techniques—X-ray absorption near-edge structure (XANES) and extended X-ray absorption finestructure (EXAFS)—we demonstrate that although the films are amorphous in long-range order, their short-range structure is dominated by ZnO- and SnO₂-like units. These local motifs are found to significantly influence conduction band hybridization, thereby affecting charge carrier mobility, concentration, and band gap values. Complementary in situ X-ray photoelectron spectroscopy (XPS) and scanning tunneling spectroscopy (STS) measurements reveal a measurable blue shift of ~0.33 eV in the electronic band gap, attributed to quantum confinement. STS results are compared with optical band gaps obtained from Tauc analysis of UV-Vis spectra. Together, these findings deepen our understanding of the structure–property relationships in a-ZTO and offer insights for the rational design of next-generation transparent electronic materials.

Room 1: Megas Alexandros

Room 2: Achilles

09:00 - 09:40

PLENARY 9

Clark Bright

Chair: Vassilios Binas (Aristotle University of Thessaloniki)

09:00 - 09:40 Metallic Thin Films: Back to the Future Presenter: Clark Bright (Bright Thin Films Solutions LLC) View abstract Hide abstract Abstract: Many applications for the mid infrared (IR) waveband (3 um – 5 um) and far IR waveband (8 um – 12 um) require the use of a transparent conductive coating (TCC). Typically, there are three choices for the TCC: doped metal oxides, i.e., transparent conductive oxides (TCO), e.g., indium oxide or zinc oxide; very thin metallic films, e.g., silver, gold and silver-gold alloys; or grid or mesh patterned opaque EC coatings. A review of some quite old previous results (Ref 1 – 3), and a limited literature review of previous and current results were analyzed and compared with the requirements of some typical applications in these two wavebands. While physics doesn’t change, our understanding of these laws does and technology advances. Our better understanding, means we can meet more demanding application requirements. In a recent paper (2024), I discussed transparent conductive oxides (TCO) and the impact of the carrier concentration N on the mobility u, and therefore, on the plasma wavelength and the spectral transmittance bandwidth. Lowering N, allows transmittance further into the near infrared. However, eventually, N will become so low that the TCO is no longer degenerate, and it becomes a semiconductor rather than a true (“metallic”) conductor. This makes using a TCO problematic in the mid IR waveband and very compromised in the far IR waveband. A better choice for a TCC for these two IR wavebands may be very thin metallic films. A second paper in 2024 discussed achieving high transmittance with very thin metallic films, which were inhibited from having an island type structure and becoming electrically discontinuous. With these techniques, very thin metallic films can be an effective TCC with good IR transmittance. Measured results and some calculated results for these films are compared with “current” application requirements.

09:40 - 10:20

PLENARY 10

George Adamopoulos

Chair: Vassilios Binas (Aristotle University of Thessaloniki)

09:40 - 10:20 Solution-Processed YIZO-Based Synaptic Transistors for Neuromorphic Applications Presenter: George Adamopoulos (Department of Electronic, Electrical and Systems Engineering, School of Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom) View abstract Hide abstract Abstract: Neuromorphic electronics, which emulate the operational principles of neural synapses, represent an emerging computing paradigm emphasising cognitive computing capabilities. This paradigm combines rapid parallel processing with high energy efficiency, significantly advancing beyond traditional von Neumann computing systems. Essential synapse-like device characteristics such as history-dependent analogue states and non-volatile memory have enabled the realisation of two-terminal memristive structures, phase-change memories, and ferroelectric memories as fundamental building blocks of neuromorphic systems. These devices exhibit key synaptic properties by temporally separating signal transmission and the self-learning process, a critical attribute for cognitive computing. However, this temporal separation remains a limitation inherent to two-terminal devices. In contrast, synaptic transistors (three-terminal devices) perform both signal transmission and self-learning processes concurrently, providing enhanced synapse emulation. Various device architectures and materials have demonstrated synaptic transistor behaviour, notably floating-gate, electrolyte-gate, ferroelectric-gate, and metal oxide dielectric configurations. This talk specifically focuses on oxide-based synaptic transistors, a class of materials capable of operating at high frequencies without the need for additional switching elements. These materials offer tunable properties and compatibility with CMOS device fabrication techniques. We present and discuss synaptic properties observed in solution-processed thin-film transistors (TFTs) employing Y2O3:Al dielectrics and semiconducting channels based on YIZO. Our findings demonstrate variable synaptic functionality across frequencies ranging from 10 mHz to 90 kHz, supported by detailed performance analysis through the paired pulse facilitation index and frequency response. Additionally, the underlying conduction mechanisms enabling synaptic behaviour are examined and discussed.

10:20 - 10:50

COFFE BREAK

10:50 - 11:20

I7

Ulrike Kraft

Chair: Juia Medvedeva (Missouri S&T)

10:50 - 11:20 Stretchable conducting polymers and devices for biosensing applications Presenter: Ulrike Kraft (Max Planck Institute for Polymer Research) View abstract Hide abstract Abstract: The low elastic modulus of polymers matches that of soft biological tissues and draws increasing interest towards soft and even stretchable health-monitoring devices. However, for these applications, the electronic and mechanical properties of conducting polymers and devices still need to be improved. Furthermore, organic electrochemical transistors (OECTs) currently attract vast interest for biosensing applications due to their mixed electronic and ionic conduction, which makes them ideal transducers of biological signals. Moreover, due to their low operating voltages (<1V), these devices are of special interest for sensing applications in close contact to the human body and especially for sensing applications in aqueous environments with liquid analytes. The first part of my talk will focus on our work on biosensors based on planar OECTs, which are able to e.g. detect the SARS-CoV-2 spike protein down to 10-17 molar concentrations in aqueous PBS, artificial saliva, and human serum solutions with good specificity[1]. In the second part of this talk, I will summarize our efforts on stretchable electronics including a fast reliable and easy transfer-printing method for the deposition of conductive polymer films on stretchable, biodegradable substrates.[2] Taking advantage of this method and infusing the substrates with small-molecule plasticizers that also diffuse into PEDOT:PSS films improves the electrical performance as well as the mechanical properties and enables a unique platform for fundamental insights into the behavior of stretchable electronic materials and devices.[3] Finally, I will present our work towards intrinsically stretchable OECTs. [1] R. Colucci, D. A. Koutsouras, S. Morsbach, P. Gkoupidenis, P. W. M. Blom, U. Kraft ACS Applied Electronic Materials, 2024, 6, pp. 2739. [2] C. Volkert, R. Colucci, R. Berger, P. Besenius, P. W. M. Blom, U. Kraft J. Mater. Chem. C, 2024, 12, pp. 3865. [3] C. Volkert, M. Brzezinski, P. Gomez, R. Colucci, S. H. Parekh, P. Besenius, J. J. Michels, U. Kraft Advanced Science, 2025, 2502853, DOI: 10.1002/advs.202502853.

I8

Berit Goodge

Chair: George Adamopoulos (Department of Electronic, Electrical and Systems Engineering, School of Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom)

10:50 - 11:20 Advances in electron microscopy for atomic-scale insights to engineer functional oxide thin films Presenter: Berit Goodge (Max Planck Institute for Chemical Physics of Solids) View abstract Hide abstract Abstract: Recent instrumentation and data processing developments have expanded the access for local, high-resolution structural investigations by electron microscopy across a wide temperature range; we apply these advances to two model Ruddlesden-Popper oxide systems to investigate the impact of octahedral lattice distortions on functional properties.

11:20 - 11:50

I9

Fabio Cicoira

Chair: Juia Medvedeva (Missouri S&T)

11:20 - 11:50 Repairable, Recyclable, and Stretchable Electronic Materials Presenter: Fabio Cicoira (Polytechnique Montreal) View abstract Hide abstract Abstract: This talk presents recent advances in the development of self-healing and stretchable conducting materials based on PEDOT:PSS blends. While conducting polymers offer unique advantages for wearable and bioelectronic applications, their poor mechanical properties limit their use in damage-prone environments. To address this, our group has engineered composite materials by blending aqueous PEDOT:PSS with mechanically adaptive polymers such as PVA, PEG, polyurethanes, and tannic acid. These materials exhibit tunable electrical and mechanical properties, enabling self-repair after damage and compatibility with printing techniques. Various types of self-healing mechanisms will be discussed, along with applications in epidermal electronics, electronic tattoos, and soft bioelectronic devices. This work supports the development of more sustainable, durable, and recyclable electronic systems.

I10

Tomas Kubart

Chair: George Adamopoulos (Department of Electronic, Electrical and Systems Engineering, School of Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom)

11:20 - 11:50 Reactive High Power Impulse Magnetron sputtering of oxide thin films Presenter: Tomas Kubart (Uppsala University) View abstract Hide abstract Abstract: Thin films of metal oxides are widely used in many applications. In general, there is a great interest in deposition techniques that enable phase control of oxide thin films. However, synthesis of crystalline films may be challenging when the growth temperature is limited, for instance on temperature sensitive polymer substrates. TiO2 is one example of a material where specific crystallinity is frequently required. Physical vapour deposition methods such as magnetron sputtering can reduce the growth temperature by employing energetic species. The growth of crystalline TiO2 thin films by physical vapor deposition techniques typically requires a deposition temperature well above 200°C. Therefore, this contribution deals with reactive magnetron sputter deposition of TiO2 thin films with ion assistance using reactive high power impulse magnetron sputtering (HiPIMS). Specifically, energy input during the film growth is analyzed and different contributions are discussed. It is shown that the geometry of the deposition system is an important factor. With a long target-substrate distance, the total energy flux is too low and the deposited films remain X-ray amorphous irrespective of the ion energy unless substrate heating is applied. Despite that, films prepared by an optimized HiPIMS process exhibit up to 3 times higher photocatalytic activity evaluated by photodegradation of stearic acid, as compared to reference pulsed DC films prepared using the same setup. Furthermore, by tuning the oxygen partial pressure and deposition rate, the internal disorder in the deposited thin films can be increased, making them suitable for crystallization during post-deposition annealing. When the target-to-substrate distance is reduced, the total energy flux is increased. As a result, the film crystallinity is greatly improved. Growth of anatase as well as rutile can be achieved by changing the total deposition pressure. Even here, the HiPIMS process facilitates crystallization of the films as compared to pulsed DC. The deposition, however, results in a pronounced unintentional heating of the substrate and the ion energy is only a smaller part of the total energy input. In summary, the HiPIMS deposited films clearly outperforms the ones prepared by pulsed DC. Although the exact growth conditions depend on the deposition geometry and specifics of the deposition setup, some general trends can support the process development.

11:50 - 12:50

O13-15

                                                        Chair: 

Juia Medvedeva (Missouri S&T)

11:50 - 12:10 Two-Layer ITO Metallization in Transparent Electronics Presenter: Doga Selin Memikoglu (KTH Royal Institute of Technology) View abstract Hide abstract Abstract: Enabling invisible electronics requires that both transistors and interconnects are transparent in the visible spectrum. We present a two-layer ITO metallization with 2 um half-pitch within a silicon-based CMOS platform. A dry etching recipe using ICP-RIE (CH4/Cl2/H2) with SiO2 hard mask is developed to etch ITO to CMOS metal interconnect patterns. ITO to ITO contact was found to have an average contact resistance of 85 Ω. TiW/Al and TiN/Al to ITO contacts were investigated as potential measurement pad materials. TiN/Al measurement pads demonstrated compatibility with the ITO layer, with acceptable contact resistance.
12:10 - 12:30 Optical anisotropy of pristine and reduced V2O5(010) Presenter: Brian Walls (Trinity College Dublin) View abstract Hide abstract Abstract: The optical properties of pristine and reduced semiconducting vanadium pentoxide single crystals are examined by the combination of reflectance anisotropy spectroscopy and x-ray diffraction. The different vanadium oxides find a range of applications, however their reduction is complex and not fully understood. The coexistence of multiple phase upon reduction is a challenge but can also be utilized in resistive switching, for example. We identify spectral features of multiple phases including V2O4, VO2, V4O9 and V6O13.
12:30 - 12:50 Hyper-gap transparent conductor & superconductor Presenter: LING LU (Institute of Physics, Chinese Academy of Sciences) View abstract Hide abstract Abstract: An elusive conductor with perfect optical transparency holds revolutionary potential for fields such as optoelectronics and nanophotonics. This hypothetical metal possesses an unprecedented spectral gap, dubbed the “hyper-gap” in its absorption spectrum, separating the intra-band and inter-band absorptions, in which the optical losses could completely vanish — a property currently achievable only within the bandgap of insulators. However, realizing such a hyper-gap metal demands an exotic electronic structure, where the conducting bands have a bandwidth narrower than their energy separations from the remaining electronic states. Despite decades of searching, no evidence has yet surfaced on where this material might be found or if it is even possible. Here, we present the first observation of this long-sought-after hyper-gap in a family of organic metals, the Fabre charge-transfer salts, through first-principal predictions coupled with both electrical and optical measurements. A remarkable transparent window, spanning from visible red to near-infrared wavelengths, is identified in bulk single crystals that remain transmissive over thirty microns thick. The corresponding absorption coefficient is the lowest recorded among all known stoichiometric metals, rivaling that of commercial thin films of transparent conductive oxides. This discovery introduces a new path, beyond traditional doping strategies in insulators, to combine electronic conduction and optical transparency in intrinsic solids.

O16-18

                                                        Chair: 

George Adamopoulos (Department of Electronic, Electrical and Systems Engineering, School of Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom)

11:50 - 12:10 High sensitivity H2 gas sensor gas sensor utilizing large on/off ratio of amorphous In-Ga-Zn-O thin film transistor Presenter: Atsushi Shimizu (Institute of Science Tokyo) View abstract Hide abstract Abstract: Amorphous oxide semiconductors, (AOSs) such as amorphous In-Ga-Zn-O (a-IGZO), are widely used as channel materials in thin film transistors (TFTs) for flat-panel displays. Applications of AOS TFTs are extended beyond displays e.g. to gas sensors. a-IGZO TFTs can attain large on/off ratios more than 10 orders of magnitude, so the a-IGZO TFT gas sensors are expected to achieve ultra-high sensitivity. a-IGZO TFT gas sensors have been applied to detection of NO2 and volatile organic molecules so far. However, only a-IGZO thin film has been used for H2 gas detection, and there have been a few reports using a-IGZO TFTs. In this study, we fabricated a-IGZO TFTs with good switching characteristics at high temperatures where H2 gas sensor operates and realized high sensitivity H2 gas sensor.
12:10 - 12:30 Two-dimensional electron (2DEG) and hole (2DHG) gases onto beta-Ga2O3 Presenter: Ekaterine Chikoidze (CNRS) View abstract Hide abstract Abstract: A new generation of UWBG semiconductors will open new territories for higher power rated power electronics and solar-blind deeper ultraviolet optoelectronics. Gallium oxide - Ga2O3 (4.5-4.9 eV), has recently emerged pushing the limits set by more conventional WBG (~3 eV) materials such as SiC & GaN as well as for transparent conducting oxides (TCO) like In2O3, ZnO and SnO2 to name a few. While there are several n-type transparent semiconductor oxides (TSO) for optoelectronic applications their required p-type counterpart oxides are known to be more challenging. We have demonstrated that Ga2O3 is also the intrinsic (or native) p-type TSO. [1] In 2019, we first reported [2] a two-dimensional electron gas (2DEG) onto beta-Ga2O3, a solid that is a pure insulator in its bulk but has a metallic conductive termination presenting a two-dimensional conductive channel at its surface. β-Ga2O3 thin films exhibited degenerate semiconductor conduction with a room temperature n = 8×1018 cm-3 electron concentrations and µ = 19 cm2/Vs Hall electron mobility. Under the Thomas-Fermi approximation, the sheet charge concentration of the 2DEG is ns ~ 2×1014 cm-2. This 2DEG was found to be resistant to high dose proton irradiation (2 MeV, 5 × 1015cm−2 dose) and was largely invariant (metallic) over the phenomenal temperature range of 2 K -850 K. In 2023, we first reported [3] a two-dimensional hole gas (2DHG) onto beta-Ga2O3. Although two-dimensional electron gases have been realized in a number of semiconductor surfaces, examples of two-dimensional hole gases (2DHG) - the counterpart to 2DEG - are still very limited. In this work, we report what appears to be an exceptional p-type 2DHG surface on a Si-doped monoclinic (010) β-Ga2O3 epitaxial films which are n-type in the bulk. The majority of the free carries at the surface have been determined to be holes with a sheet concentration of p ~ 8.7×1013 cm-2 and a puzzlingly high mobility value of µh ~ 80 cm2/(V·s) at room T. 1. E.Chikoidze et al, Journal of Materials Chemistry C. 7, 10231 (2019) 2. E. Chikoidze, D. J. Rogers, F. H. Teherani, C. Rubio, G. Sauthier, H. J. Von Bardeleben, T. Tchelidze, C. Ton-That, A. Fellous, P. Bove, É. V Sandana, Y. Dumont, A. Perez-Tomas, Materials Today Physics, 8, 10 (2019). 3. E. Chikoidze, J. Leach, Z. Chi, J. von Bardeleben, B. Ballesteros, A.-M. Gonçalves, T. Tchelidze, Y. Dumont, A. Pérez-Tomás, Journal of Alloys and Compounds, 271, 172713 (2024).
12:30 - 12:50 Transparent and conductive codoped-ZnO thin films (IGZO, IAZO, AGZO) deposited by ultrasonic chemical spray technique Presenter: MARIA DE LA LUZ OLVERA AMADOR (Center for Research and Advanced Studies, Cinvestav) View abstract Hide abstract Abstract: Indium doped zinc oxide (IZO) thin films were deposited onto soda-lime glass substrates by the ultrasonic chemical spray (USP) technique. The influence of different Zn precursors (zinc acetate, AcZn, zinc sulfate, SZn, and zinc chloride, CZn), used in the preparation of the starting solutions, on the structural, optimal, morphological and electrical characteristics was analyzed. Starting solutions were prepared with a molar concentration of 0.2M and an atomic concentration of In of 3 at%. The deposition conditions were kept constant, with a substrate temperature of 450 °C and a deposition time of 12 min. From the structural analysis, a preferential orientation along the (101) plane was observed for all IZO films. The optical transmission oscillated in the range of 61-81 %, confirming the transparency of all deposited films. The bandgap values, Eg, around 3.5 eV, showed slight variations with the different types of Zn precursor employed. The films were designed for being employed as Transparent Conductive Oxide (TCO) films, in this respect, the best figure of merit or quality factor for TCO applications were obtained in the IZO films doped with 3 at% of In in the starting solution, with a value of 2.49x10-3 (Ω/□)-1, calculated from an optical transmission of 81 % and a sheet resistance of 50 Ω/□. According to the results obtained, IZO thin films deposited by USP technique are potentially applicable in the field of optoelectronics, mainly as transparent electrode.

12:50 - 14:50

LUNCH BREAK

14:50 - 15:30

PLENARY 11

Chris Van de Walle

Chair: Elisabetta Comini

14:50 - 15:30 Hydrogen in indium oxide and gallium oxide Presenter: Chris Van de Walle (University of California, Santa Barbara) View abstract Hide abstract Abstract: Hydrogen is often unintentionally present in indium oxide and gallium oxide. We assess its impact on the properties of these materials using first-principles calculations based on density functional theory. In both materials hydrogen acts as a shallow donor, but its behavior changes in AlGaO alloys. Hydrogen can also interact with other impurities or defects in the material. We have also addressed diffusion of hydrogen.

15:30 - 16:10

PLENARY 12

Wen Ruitao

Chair: Elisabetta Comini

15:30 - 16:10 Electrochromic materials for visible and near infrared light modulation Presenter: Ruitao Wen (Southern University of Science and Technology) View abstract Hide abstract Abstract: Electrochromic materials can reversibly change their optical properties by varying the external electrical stimuli. Since the first experimental demonstration of electrochromic phenomenon in tungsten oxide, electrochromic technology has been extensively developed. Currently, electrochromism based devices can be found in windows of energy efficient buildings, smart phones, goggles, information displays, anti-glare rear-view mirrors, etc. In inorganic electrochromic materials, transition metal oxides are most studied, and oxide thin films can change colors and transmittance of the near-infrared between a transparent and a colored state upon small ion intercalation. In an electrochromic material or device, an ideal scenario is that visible and near-infrared light can be independently regulated, that is bright mode (both VIS and NIR are highly transparent), cold mode (transparent for VIS but not for NIR), warm mode (transparent for NIR but not for VIS) and dark mode (both VIS and NIR are blocked). However, electrochromic devices typically suffer from single-mode control, i.e., simultaneously varying the visible and near-infrared light. Electrochromic effect combined with surface localized plasma resonance (LSPR) were recently found to be able to sequentially modulate near-infrared and visible light. In this talk, we report our recent progress on dual-band modulation, with a special focus on achieving a transition from bright mode to warm and dark mode, as well as bright mode to cool and dark mode. We believe our findings show substantial fundamental insight into electrochromism in cathodic oxides, and provide a new starting point for designing electrochromic devices with superior performance.

16:10 - 16:40

COFFE BREAK

16:40 - 17:20

PLENARY 13

Norifumi Fujimura

Chair: Tetsuya YAMAMOTO (Kochi University of Technology)

16:40 - 17:20 Novel chemical vapor deposition process of ZnO and Ga2O3 films by nonequilibrium atmospheric pressure N2/O2 Plasma Presenter: Norifumi Fujimura (Osaka Metropolitan Univ.) View abstract Hide abstract Abstract: We successfully generated a nitrogen plasma at near-atmospheric pressure characterized by a high electron temperature (>4000 K) and a low gas temperature (<400 K) using dielectric barrier discharge. Utilizing this non-equilibrium nitrogen plasma, in which the emission of the N₂ second positive system was predominantly observed, we achieved self-limited nitridation of Si with a thickness of approximately 1.8 nm at room temperature. The leakage current of the resulting nitride film was found to be more than two orders of magnitude lower than that of films nitrided using RF plasma, where atomic nitrogen active species are predominantly observed. In addition, oxidation was detected upon the introduction of only 1 ppb O₂ gas. Furthermore, we will present the low-temperature growth of oxide films such as ZnO and Ga₂O₃ using this near-atmospheric-pressure plasma in combination with a home-built chemical vapor deposition system.

17:20 - 18:00

PLENARY 14

Holger von Wenckstern

Chair: Tetsuya YAMAMOTO (Kochi University of Technology)

17:20 - 18:00 Creation of Material Libraries of Wide and Ultra-Wide Bandgap Conductive Oxides by Combinatorial Pulsed Laser Deposition Presenter: Holger von Weckstern (Leipzig University) View abstract Hide abstract Abstract: The discovery of new functional materials is rapidly accelerated through combinatorial synthesis and high-throughput property screening. We discuss recent developments on the use of segmented PLD targets to fabricate continuous composition spread material libraries (CCS-MLs) of wide and ultra-wide bandgap group III and transition metal sesquioxides, being promising candidates for high-power electronics and detector applications. These CCS-MLs were comprehensively analylized using advanced analytical techniques, revealing, e.g., tunable bandgaps across wide ranges in corundum structure without phase separation. Additionally, a FAIR-compliant digital data management system for thin film deposition and characterization presented enhancing the accessibility and reusability of research data.

18:00 - 18:30

I11

Dalibor Stanković

Chair: Chris Van de Walle (University of California, Santa Barbara)

18:00 - 18:30 Transparent electrodes and semiconductor materials for electrocatalysis applications Presenter: Dalibor Stanković (Department of Analytical Chemistry, Faculty of Chemistry, University of Belgrade, Belgrade, Serbia) View abstract Hide abstract Abstract: Electrochemical catalysis is an important part of research in the modern world due to its various applications. Electrocatalysis is an important part of research for application in the development of sensors for use in environmental chemistry and biomedical research, development of capacitors, batteries, energy conversion and conservation, waste water treatment. The development of nanotechnology has significantly contributed to the accelerated development of these areas. A very important place in each of these fields of research is occupied by transparent materials and semiconductor nanomaterials.

I12

Maria Kandyla

Chair: Ruitao Wen

18:00 - 18:30 Micro/nano-structures of transparent oxides by laser processing for optoelectronics and smart surfaces Presenter: Maria Kandyla (National Hellenic Research Foundation) View abstract Hide abstract Abstract: In this talk, we will discuss the development of functional micro/nanostructures, based on transparent oxides combined with laser-processed surfaces.

18:30 - 19:50

O19-22

                                                        Chair: 

Chris Van de Walle (University of California, Santa Barbara)

18:30 - 18:50 The Plasma Plume Deflection and Target Surface Roughness During Pulsed Laser Deposition of Functional Oxides Presenter: Jonas Elz (Leipzig University) View abstract Hide abstract Abstract: The plasma plume deflection angle during pulsed laser deposition (PLD) was compared to the respective surface roughness of the target after deposition. A linear behavior was observed between the deflection angle and the root mean square roughness of the target center for different materials after 100,000 pulses, as well as for the same material during the initial 50,000 pulses.
18:50 - 19:10 Flexible, printed absorbers for shielding against microwave radiation Presenter: Emmanouil Gagaoudakis (IESL, FORTH) View abstract Hide abstract Abstract: Absorbers in microwave region of the electromagnetic spectrum are of great importance, due to their application as protective coatings against this radiation. Moreover, Perfect Metamaterials Absorbers (PMAs) have attracted much research attention during the last decade as they are able to fully absorb the microwave radiation. The PMAs are based mainly on periodic metallic structures with both specific periodicity and geometry. In the present work, the properties of conductive inks, as well as of the substrates were investigated, in order to fabricate PMAs based on printed metallic periodic structures. More specific, nanoinks based on Ag or other metals were examined as far as their morphology, viscosity, resistance etc. concern, while flexible substrates such as kapton and textiles were characterized and tested for their ability to print metallic structures on them. Finally, different geometries and sizes were tested to be printed on the substrates, according to simulations that have been done. Moreover, the metallic periodic structures fabricated by 3D printing technique on flexible substrates as well as on textiles, were investigated as perfect absorbers for electromagnetic waves in the microwave region of 9 GHz to 14 GHz. Specifically, various topologies were designed, simulated, and developed to control surface impedance and achieve electromagnetic absorption at microwave region. The level of transmission and reflection of the developed samples was measured with appropriate waveguides. From these, the absorption was calculated and found to be enhanced for these printed periodic metallic structures between 9 and 10.5 GHz, indicating a possible perfect absorber in the microwave region of EM radiation. Acknowledgements This work was supported by the “Metamaterial Products to Protect from Electromagnetic Radiation - PROPILEA” project with ID 16971 - OPS TA 5149205 funded by Greece 2.0 - National Recovery and Resilience Plan funded by the European Union – NextGenerationEU.
19:10 - 19:30 Extrinsic Doping Mechanism in Sb2O5 as a Promising n-type Transparent Conducting Oxide Presenter: Ke Li (University College London) View abstract Hide abstract Abstract: Transparent conducting oxides possess a unique combination of optical transparency and electrical conductivity, making them indispensable in optoelectronic applications. 1 However, the heavy dependence on a small number of established transparent conducting oxides (In2O3, SnO2, ZnO and Ga2O3) places limitations on the number and types of devices they can support. Additionally, the high cost due to the scarcity of rare elements raises concerns about their long-term sustainability and large-scale production. 2 Discovering more wide band gap oxides that can be doped to display metallic-like conductivity is therefore necessary. In this work, we use the PBE0 hybrid functional to investigate the defect chemistry of the binary Sb(V) system, Sb2O5. 3 We observe a large optical band gap over 3.6 eV, enabling transparency. The calculated Sb2O5 electronic structure shows a dispersive conduction band minimum with low electron effective masses, indicating the potential for high electron mobility. ShakeNBreak was used to generate different distortions for finding the groundstate structure, and Doped was used to manage all the defect calculations and analysis.4–6 A rare 4-electron negative-U behaviour was found in the Sb vacancy with an oxygen trimer and split-vacancy configuration formed. Although the intrinsic point defect study shows that Sb2O5 does not display metallic-like conductivity, with extrinsic doping of Fluorine (F), Tungsten (W) and Molybdenum (Mo), Sb2O5 displays degenerate n-type transparent conducting behaviour. Our band alignment calculations demonstrate that Sb2O5 has a larger electron affinity than the established transparent conductors, which can facilitate electron extraction for organic solar cell applications. The findings of this under-explored Sb(V) binary system demonstrate the feasibility and potential for Sb(V)-based materials to be promising transparent conducting oxides. 1. Jackson, A. J. et al. ACS Energy Lett. 3807–3816 (2022) doi:10.1021/acsenergylett.2c01961. 2. Mineral Commodity Summaries 2023. (2023). 3. Adamo, C. & Barone, V. The Journal of Chemical Physics 110, 6158–6170 (1999). 4. Mosquera-Lois, I., Kavanagh, S. R., Walsh, A. & Scanlon, D. O. JOSS 7, 4817 (2022). 5. Kavanagh, S. R. et al. JOSS 9, 6433 (2024). 6. Mosquera-Lois, I., Kavanagh, S. R., Walsh, A. & Scanlon, D. O. npj Comput Mater 9, 25 (2023).
19:30 - 19:50 Oxidation-resistant Cu-based nanowires transparent electrodes activated by an exothermic reaction Presenter: Mona Tréguer-Delapierre (ICMCB-CNRS, U.Bordeaux) View abstract Hide abstract Abstract: Metallic nanowire percolating networks are one of the promising alternatives to conventional transparent conducting electrodes. Among the conductive metals, copper appears as a relevant alternative to develop electrodes in a more sustainable and economical way (abundance of the supplies, geo-political risks regarding the supplies, environmental impact, and cost).[1] However, Cu nanowires suffer from high instability in air, and one of the ways to increase stability as well as to boost properties related to transparent electrodes is to combine the Cu with another metal, resulting in bimetallic nanowires. Even though the field of fabrication of nanoalloys has been advancing at a rapid pace in the last two decades, binary nanowires are difficult to produce due to a wide range of parameters that must be aligned in regard to metals that are being combined. We are currently experimenting how the allowing of Cu-based nanowires with nickel can be exploited for the development of metal nanowire networks with high oxidation resistance. We report a novel synthesis and a new way of optimizing performance of a CuNi transparent electrode through enhancing interconnectivity of NWs, based on a reducing treatment at room conditions.

O23-26

                                                        Chair: 

Ruitao Wen

18:30 - 18:50 Heuristic approach to the fundamental optical constants of silver nanowire networks: experiments and theory Presenter: Amaury Baret (ULiège) View abstract Hide abstract Abstract: Silver nanowire (AgNW) networks are emerging as a leading class of Transparent Conducting Materials (TCMs), offering a unique combination of high optical transparency, excellent electrical conductivity, mechanical flexibility, and scalable, cost-effective production routes. This association of properties makes them key building blocks for a wide range of devices such as photovoltaic cells, OLEDs, transparent heaters, sensors or smart windows. The conductivity of AgNW networks arises from a percolation mechanism through nanowire junctions, while their transparency results from gaps between the nanowires, illustrating an intrinsic interplay between these properties. Understanding the optical properties of AgNW networks, often described by their refractive indices (n, k), is critical for advancing their integration into multilayer systems and devices. Furthermore, refractive indices provide fundamental insight into the material’s optical behavior and enable accurate simulations of complex multilayer designs using the Transfer Matrix Method. This study combines Mie’s scattering theory and van de Hulst’s mixing model to theoretically determine the refractive indices of AgNW networks without relying on fitting parameters. For the first time, refractive indices across the visible and near-infrared spectrum are calculated and validated upon experimental results. Transmittance spectra, derived from numerical solutions of Fresnel’s equations, show strong agreement with measurements, particularly for nanowires with larger diameters and at shorter wavelengths, with a relative error below 10% at 𝜆=550 nm. Crucially, the findings of the present research also highlight for the first time in optical measurements the predominantly metallic optical behavior of AgNW networks deposited on glass substrates. By accurately modeling the optical properties of AgNW networks, this work facilitates their integration into multilayer optical systems, supporting the development of innovative devices such as displays, sensors, and energy-efficient smart windows. Additionally, this research paves the way for a more advanced theoretical understanding of the optical properties of silver nanowire networks at the fundamental level.
18:50 - 19:10 QM/MM Investigations of Defects in MgO and Their Use as a Model System for High-Tc Superconductivity Presenter: Liam Morgan (University College London, STFC) View abstract Hide abstract Abstract: Hole states in Cu-doped MgO and F-centre excitons in MgO are investigated using modern hybrid quantum mechanical - molecular mechanical (QM/MM) simulation techniques. The former system is used as a model system for superconducting cuprate materials, whilst the latter is compared with previously reported theory of hydrogenic behaviour of excited states.
19:10 - 19:30 Full Subgap Defect Density of States in p- and n-type Metal Oxide Transistors Presenter: Måns Mattsson (Oregon State University) View abstract Hide abstract Abstract: Recent developments in the Ultrabroadband Photoconductive Density of States (UP-DoS) method enable the acquisition of full subgap DoS on metal oxide thin-film transistors (TFTs), including InGaZnOx, SnO and Cu2O channel materials.[1,2] To achieve full valence-to-conduction band edge coverage, we continuously scan the incident laser photon energy from hv = 0.1 to 3.6 eV, yielding an integrated trap density, N_tot(hv), that increases stepwise as each subsequent subgap defect state is ionized. The identity of each defect peak is assigned by comparing the derivative UP-DoS spectra, dN_tot/dhv, to both DFT+U simulations and experimental defect recombination lifetimes.[1,2] For p-type channel TFTs, UP-DoS spectra of SnO and Cu2O reveal metal vacancy peaks near the valence band maximum that determine the TFT equilibrium hole concentration and Fermi level energy. Due to its measured small bandgap of 0.7 eV, unipolar p-type transistor behavior in SnO is achieved only when the defect DoS near the conduction band minimum, attributed to oxygen interstitials, is sufficiently large to suppress n-type conduction. For Cu2O TFTs, UP-DoS reveals the presence of a minority phase of CuO existing at a heavily oxidized semiconductor-dielectric interface. This oxidized minority phase explains the large discrepancy between the measured Hall mobility (μ_Hall = 20 cm2V-1s-1) and field effect mobility (μ_FE = 0.2 cm2V-1s-1) for Cu2O thin-films.[1] In contrast to p-type materials, n-type amorphous InGaZnOx is dominated by oxygen vacancies with different neighboring metal coordinations. Near the conduction band edge, UP-DoS reveals the presence of a broad Gaussian electron trap state centered at 0.4 eV. Using a 10K atom DFT+U simulation, this defect state is further assigned as a (In In In Ga) coordinated oxygen vacancy. For 15 different TFT processing conditions, UP-DoS measures the trap density of this In-rich electron trap state to show an inverse correlation with both TFT mobility and subthreshold swing. This correlation is validated using a first-principles DoS mobility model that shows the tail-state condunctivity requires the inclusion of this broad shallow donor peak to reasonably simulate a-InGaZnOx TFT transfer curves. Finally, we reconfigure our UP-DoS microscopy method to use high-power femtosecond lasers that selectively ionize specific defects while also annealing the amorphous InGaZnOx lattice. The end result suggests a fundamental transformation of the active-channel material that boosts field-effect mobility >10x, with minimal impact on TFT reliability. [1] Mattsson, M. J., Niang, K. M., Parker, J., Meeth, D. J., Wager, J. F., Flewitt, A. J., & Graham, M. W. (2025). Defect Density of States of Tin Oxide and Copper Oxide p‐type Thin‐film Transistors. Advanced Electronic Materials, 2400929. [2] Mattson, G. W., Vogt, K. T., Wager, J. F., & Graham, M. W. (2023). Illuminating trap density trends in amorphous oxide semiconductors with ultrabroadband photoconduction. Advanced Functional Materials, 33(25), 2300742.
19:30 - 19:50 Electrical Properties of Heterostructure Metal - Polyarylene Ether Ketone Copolymer - TCO Presenter: Alla Chebotareva (Lomonosov Moscow State University, SINP MSU) View abstract Hide abstract Abstract: The report presents the study of the unique properties of non-conjugated transparent polymers from the class of aromatic polyether - polyarylene ether ketones, - to form low resistance electrical contact metal/polymer/transparent conductive oxide (TCO). The conductivity mechanisms in thin polymer films in the heterostructure metal/polymer/TCO have been investigated experimentally. Particular attention has been paid to the electronic structure of polymers and mechanisms of a highly conductive state (HCS) formation.

Room 1: Megas Alexandros

Room 2: Achilles

09:00 - 09:40

PLENARY 15

Elisabetta Comini

Chair: Norifumi Fujimura

09:00 - 09:40 From Sensing to Energy: Metal Oxide Nanostructures for Green Technologies Presenter: Elisabetta Comini (University of Brescia) View abstract Hide abstract Abstract: Metal oxides are versatile functional materials widely used in sustainable technologies due to their chemical stability, tunable electronic properties, and ease of integration into miniaturized systems. In the field of chemical sensing, they serve as highly sensitive and selective materials capable of detecting a wide range of gases and biomolecules, which is essential for real-time monitoring in lab-on-a-chip devices and point-of-care medical diagnostics. These applications benefit from the miniaturization, low power consumption, and fast response times enabled by metal oxide-based sensors. Beyond sensing, metal oxides—such as NiO, ZnO, and CeO₂-based composites—play a critical role in the development of next-generation energy conversion systems like Solid Oxide Fuel Cells (SOFCs). Their function as catalysts and electrode materials supports efficient electrochemical reactions, enabling clean energy production from hydrogen or bio-derived fuels. Integrating these materials into multifunctional platforms bridges the gap between sensing and energy, paving the way for self-powered diagnostic tools and compact, eco-friendly devices. From a sustainability standpoint, metal oxides offer high availability, recyclability, and compatibility with low-temperature fabrication methods, making them ideal candidates for scalable, green technologies that align with circular economy goals and carbon neutrality strategies. We will explore the synthesis, characterization, and performance evaluation of chemical sensors and Solid Oxide Fuel Cells (SOFCs) using nanostructured materials. These samples were characterized using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Raman spectroscopy. Electrochemical performance, including I–V characteristics and Electrochemical Impedance Spectroscopy (EIS), was evaluated at different temperatures and gas flow conditions.

09:40 - 10:20

PLENARY 16

Tetsuya Yamamoto

Chair: Norifumi Fujimura

09:40 - 10:20 Materials Design of High Carrier Transport Oxide Films for Various Applications Presenter: Tetsuya YAMAMOTO (Kochi University of Technology) View abstract Hide abstract Abstract: We have developed highly transparent conductive oxide (TCO) films based on n-type-doped zinc oxide (ZnO) and indium oxide (In₂O₃) with thicknesses (t) ranging from a few nanometers to micrometers. Our main concern is achieving high carrier transport (e.g., 145 cm^2/(Vs)) at high carrier concentrations (N) ranging from 2×E+20 to 2×E+21 cm^-3, independent of t. The N and t values depend heavily on the application. Transparent conductive electrodes, for example, require t values ranging from 100 to 150 nm for solar cells and liquid crystal displays (LCDs); electromagnetic shielding requires t values greater than 1 μm; gas sensors require t values of 50 nm; γ-radiation resistance requires t values of 200 nm; and antibacterial applications require t values of 50 nm. Recently, we achieved high Hall mobility in polycrystalline W-doped In₂O₃ (IWO) with t below 10 nm. We have successfully fabricated continuous, 2-nm-thick amorphous IWO films on glass substrates. In this talk, we will discuss how to achieve TCO films with high carrier transport and explain the physics of the free electron system in IWO films, which differs from that of most metals, and discuss dominant factors governing carrier transport.

10:20 - 10:50

COFFE BREAK

10:50 - 11:20

I13

Junjun Jia

Chair: Holger von Weckstern (Leipzig University)

10:50 - 11:20 Switching the Transparency of Semiconductor Thin Films Presenter: Junjun JIA (Waseda University) View abstract Hide abstract Abstract: When a semiconductor material is irradiated by an intense laser with excitation energy larger than its band gap, a large number of valence electrons can be excited into its conduction band. These excited electrons rapidly relax, and then transiently occupy at the bottom of the conduction band. Such transient occupation, named transient Pauli blocking effect [1, 2], reduces the material’s ability to absorb light, potentially enabling the switching from an opaque state to a transparent one on ultrafast timescales. This physics provides a foundation for designing ultrafast optical switching devices. Even more remarkably, when the laser is modulated at ultrahigh speeds, the effect can be dynamically controlled, unlocking new possibilities for advanced optical technologies [1]. In this talk, I will present recent progress in ultrafast optical switching in semiconductor films, with a particular focus on multivalley materials [1]. By irradiating the multivalley material Ge with an intense pulsed laser, ultrafast optical switching between transparency and opacity across a wide wavelength range is achieved. Femtosecond time-resolved transient transmission measurements revealed that this ultrafast optical switching occurs in both the Γ and L valleys, enabled by intravalley and intervalley scattering processes. Moreover, I also will discuss the shift in plasmon resonance wavelength in transparent conducting materials induced by intense laser irradiation, which offers an additional pathway for developing optical switching devices [3]. These works are expected to open new doors for possible applications in optical multiband communications, optical computing, and beyond. This work is supported by JSPS KAKENHI Grant-in-Aid for Scientific Research (B) (Grant No. 25K01862). References: [1] J. Jia, H. A. Almossalami, H. Ye, N. Yamada, T. Yagi, Phys. Rev. Applied, 23, 024060 (2025). [2] J. Jia, T. Yagi, M. Mizutani, N. Yamada, and T. Makimoto, J. Appl. Phys. 132, 165702 (2022.) [3] Q. Hu, J. Jia, et al., ACS Photonics, 10, 3612 (2023).

I14

Ilya Sychugov

Chair: Emmanouil Gagaoudakis (IESL, FORTH)

10:50 - 11:20 Nanomaterials for Semi-Transparent Photovoltaics and Transparent Wood Presenter: Ilya Sychugov (KTH Royal Institute of Technology) View abstract Hide abstract Abstract: Quantum dot and metal nanocluster based large area luminescent solar concentrators will be presented. Both material and device properties will be discussed together with system integration prospects. A relatively new transparent material, namely transparent wood, will be shown and how its preparation parameters affect resulting composite optical properties, such as transparency and haze.

11:20 - 11:50

I15

Spyros Kassavetis

Chair: Holger von Weckstern (Leipzig University)

11:20 - 11:50 Colloidal Metal Oxides for Printed Electronics Presenter: Spyros Kassavetis (Aristotle University of Thessaloniki) View abstract Hide abstract Abstract: Colloidal Metal Oxides for Printed Electronics

I16

Piero Mazzolini

Chair: Emmanouil Gagaoudakis (IESL, FORTH)

11:20 - 11:50 Challenges and perspectives in r-GeO2 heteroepitaxy Presenter: Piero Mazzolini (Department of Mathematical, Physical and Computer Science, University of Parma, Italy) View abstract Hide abstract Abstract: The ultra-wide bandgap semiconductor rutile germanium oxide (Eg = 4.6 eV) has the potential to rapidly become the new big actor in the field of power electronics.[1] In comparison with the widely investigated β-Ga2O3, a major potential advantage of r-GeO2 is the predicted possibility to obtain ambipolar doping for pn homo-junctions device architectures. Experimentally, it has been already demonstrated its bulk growth with controllable n-type conductivity (Sb).[2] While this opens up for the future evolution of homoepitaxy, at present bulk r-GeO2 substrates are not commercially available; therefore, the development of this material system must rely on heteroepitaxy. Its epitaxial growth faces two major challenges: (1) the two-step growth kinetics involving the preliminary formation of the volatile GeO suboxide (limiting its growth rate)[3] and (2) the strong competition between the amorphous material and the rutile phase stabilization.[4] In this work we cover such aspects by investigating r-GeO2 epitaxial layers deposited by MOVPE on different orientations of isostructural r-TiO2 substrates. By combining experimental (e.g., (S)TEM, SEM, XRD, AFM, EBSD) and theoretical data we will focus on strain, faceting and growth rate in defining the overall structural quality of the deposited epilayers. [1] S. Chae, J. Lee, K. A. Mengle, J. T. Heron, E. Kioupakis, Appl. Phys. Lett. 2019, 114, 102104. [2] Z. Galazka, R. Blukis, A. Fiedler, S. Bin Anooz, J. Zhang, M. Albrecht, T. Remmele, T. Schulz, D. Klimm, M. Pietsch, A. Kwasniewski, A. Dittmar, S. Ganschow, U. Juda, K. Stolze, M. Suendermann, T. Schroeder, M. Bickermann, Physica Status Solidi (b) 2024, 2400326. [3] W. Chen, K. Egbo, H. Tornatzky, M. Ramsteiner, M. R. Wagner, O. Bierwagen, APL Materials 2023, 11, 071110. [4] S. Chae, H. Paik, N. M. Vu, E. Kioupakis, J. T. Heron, Appl. Phys. Lett. 2020, 117, 072105.

11:50 - 12:50

O27-29

                                                        Chair: 

Emmanouil Gagaoudakis (IESL, FORTH)

11:50 - 12:10 Protection of Transparent Electrodes based on metallic nanowires by nitrides deposited by Plasma-Enhanced ALD Presenter: Maria del Mar Rodriguez Robles (SIMaP( Science and Engineery of Materials and Processes)) View abstract Hide abstract Abstract: Transparent electrodes (TEs) are critical components of many devices in daily life, such as displays, wearable electronics, solar cells, sensors, and many more. They consist of a transparent conductive material (TCM) deposited on a transparent substrate; silver nanowires (AgNWs) assembled within a percolation network are promising TCMs not only because of their physical performance but also due to their high mechanical flexibility and compatibility with cost-effective solution-based techniques. However, their performance and integration into devices are limited by their morphological instability caused by the high surface effects. The current work investigated the possibility of coating such Ag nanowires with a robust and stable AlN diffusion barrier by Plasma-Enhanced ALD to enhance the thermal, electrical, and mechanical stability of the TEs while keeping a high optical transmittance due to the high optical bandgap of AlN (6.42 Ev).
12:10 - 12:30 New evaluation method on various gas barrier performances using functional oxide films (1); O2 or H2O barrier properties Presenter: Minseok Kim (Aoyama gakuin university) View abstract Hide abstract Abstract: Recently, the development of electronic devices on flexible substrates such as polyethylene terephthalate (PET) has been challenged by their poor intrinsic gas barrier properties compared to glass or silicon substrates. As device components are susceptible to degradation caused by atmospheric oxygen or water vapor gas, achieving low water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) are important to ensure device stability and reliability. Among various candidates, amorphous zinc tin oxide (a-ZTO) and amorphous silicon nitride (a-SiNx) films have emerged as promising materials due to their excellent gas barrier performance.[1-3] In this study, a-ZTO1) or a-SiNx2), 3) thin films with thicknesses ranging from 20 to 200 nm were deposited on glass substrates by RF sputtering using a ZTO (Zn:Sn=2:1) or Si targets, respectively. For the gas barrier evaluation, these a-ZTO and a-SiNx films were deposited onto glass substrates pre-deposited with various transparent conductive oxide (TCO) layers, such as amorphous indium zinc oxide (a-IZO)4),5) or ITO films. The as-deposited films and post-annealed films in air were evaluated in carrier density (n) of the TCO layers by Hall effect measurements in order for the quantitative estimation on how many oxigen vacacies were disappeared by the annealing oxidation, reflecting the amount of oxygen transmitted 3). Figures 1 (a)-(c) and (d)-(f) show the electrical properties of ITO and IZO thin films coated with the gas barrier layers, respectively, where the as-deposited films and the post-annealed films are indicated by ● and ▼, respectively. For ITO films [1], coating with a-SiNx (≥20 nm) prevented a decrease in carrier density after annealing at 400 °C in air, indicating excellent barrier performance. In contrast, a-ZTO films (even at 150 nm) or additional 100 nm SiNx layers on ZTO/ITO showed the decrease in carrier density, suggesting oxygen diffusion from ZTO into the ITO layer in Fig. 1-(b) and (c) because ofn the high annealing temperature of 400 °C. In the case of IZO films, the use of a-SiNx (≥20 nm) and a-ZTO (≥20 nm) films as the over layers effectively suppressed carrier reduction after annealing temperature at 250°C. With thicker ZTO films (≥150 nm) or additional 100 nm SiNx film depositions, the decrease in carrier density was negligible, confirming their oxygen barrier effects. On the evaluation on H2O vapor barrier properies Al doped ZnO (AZO) films were adopted as the TCO, that will be reported in detail in the conference.
12:30 - 12:50 Surface activation of BiVO4 for improved performance in alkaline photoelectrochemical water splitting Presenter: Anthony Sanderse (TNO) View abstract Hide abstract Abstract: This study explores scalable surface activation strategies for BiVO₄ photoanodes to improve performance in photoelectrochemical (PEC) water splitting under alkaline conditions. By integrating bimetallic NiFeOOH electrocatalysts via light-assisted electrodeposition and applying borate surface functionalization, significant improvements in oxygen evolution reaction (OER) kinetics (through improved charge transfer and increased electrochemical surface area) were achieved. The work combines structural, optical, and electrochemical characterization (including EIS) to elucidate the mechanisms behind performance improvements, offering insights into the development of more efficient and scalable PEC systems for green hydrogen production.

O30-32

                                                        Chair: 

Holger von Weckstern (Leipzig University)

11:50 - 12:10 Direct observation of the density of in-gap states of In2O3:H thin films and the origin of instability of thin film transistors Presenter: Ryotaro Nakazawa (Institute for Molecular Science) View abstract Hide abstract Abstract: Hydrogen-doped Indium oxide (In2O3:H) has attracted significant attention as a transparent oxide semiconductor used for a channel layer in thin film transistors (TFTs) owing to its high field-effect mobility (μFE ~100 cm2 V−1 s−1). However, the electron transport properties of In2O3:H are highly sensitive to deposition and annealing conditions. Furthermore, the TFTs exhibit instability issues due to electric field stress and/or UV irradiation stress. In-gap states—electronic states located within the bandgap—are key contributors to this instability. Despite their importance, in-gap states are difficult to measure because their density is extremely low. In this study, we investigate the density of in-gap states of In2O3:H thin film by high-sensitivity ultraviolet photoelectron spectroscopy (HS-UPS) using low-energy photons. Low-energy photons minimize sample damage and achieve a long probing depth. HS-UPS directly determines the energy distribution of the density of in-gap states over four orders of magnitude. Notably, we discovered the formation of photo-induced in-gap states with light irradiation stress. In this presentation, we will discuss the origin of photo-induced in-gap states and the instability mechanisms of In2O3:H-based TFTs.
12:10 - 12:30 Electrospun fiber coatings as new transparent conductive coatings Presenter: Sabine Heusing (INM – Leibniz Institute for New Materials, Saarbruecken, Germany) View abstract Hide abstract Abstract: Transparent conductive coatings (TCC) are used as transparent electrodes for displays, sensors, photovoltaics, transparent heaters, antennas, etc. Mainly, ITO (tin-doped indium oxide) layers are used as TCC, but other materials are also being investigated to replace ITO, such as layers with silver nanowires or silver nanoparticles, graphene, printed metal grids, etc. Great efforts are being made to obtain flexible and cost-effective transparent conductive coatings that can be produced in a large area. To obtain flexible and cost-effective transparent conductive coatings with low sheet resistance and high transmission, that can also be produced cost-effectively over a large area, a new technology has been used to produce TCC: the electrospinning process. Two production routes were investigated: In the first route, polymer fibers containing silver nanoparticles as nuclei were spun on polymer foil. An electroless silver coating was then applied to obtain conductive fibers. After an additional copper plating, which was performed electroless or galvanically, highly conductive coatings with a sheet resistance of 5 Ω/sq, a total transmittance of about 90 % and a low haze of 2 % or less could be obtained. In the second route, fibers with a higher metal content were spun on foil, which were already conductive after heat treatment at approx. 100 °C. By subsequent electroless copper plating, sheet resistances of 4 Ω/sq, a total transmission of about 90 % and a low haze of about 2 % were achieved. The second route is advantageous for upscaling to produce large area coatings. The fiber coatings have a very high aspect ratio: The fibers have a thickness between 1 µm and 3 µm and a length of several cm. The fiber coatings are flexible and stretchable and suitable for flexible devices with a wide range of substrates. By variation of the spinning parameter and the spinning ink, the thickness and the density of fibers can be adjusted and thus also the resistance and the optical properties. Various demonstrators, such as a transparent heater and a proximity sensor, have been produced using such electrospun fibers and the results will be presented. The use of the fibers as a transparent heater was tested with a thermal imaging camera. By heating the electrospun fiber coating with a low power density of about 12 mW/cm2, the temperature of the sample was homogeneously increased from room temperature (21 °C) to about 31 °C. This could be used for de-icing of automotive windows or blades of wind power plants. In addition, a proximity sensor was fabricated to demonstrate the properties of the electrospun fibers. Possible applications for electrospun fiber coatings are transparent electrodes for flexible displays, sensors, photovoltaics, wearables, antennas, skin patches, antistatic coatings, transparent heaters, etc. By using a roll-to-roll machine with an electrospinning unit, the fabrication of large area electrospun coatings was shown, which is currently under development to enable industrial applications.
12:30 - 12:50 Uncovering the element-specific interatomic distances throughout the Cu(Br,I) alloy system Presenter: Sandra Montag (Felix Bloch Institute for Solid State Physics, Leipzig University, Germany) View abstract Hide abstract Abstract: Copper(I) iodide (CuI) is both a transparent and p-type semiconductor with various applications, e.g. in diodes, solar cells, blue and UV LEDs and thin film transistors. [1][2] Next to various other forms of doping and alloying, anion substitution with bromide can be used to tune the free hole concentration in functional layers, enabling optimized performance of active devices.[3] To understand the change of material properties with different alloying compositions, it is vital to investigate not only the crystal structure, but the displacement of the atoms in their local environment within the crystal lattice. In consequence, X-ray absorption spectroscopy was used at the Cu, Br and I K-edges to determine the fine structure of CuBr1-xIx samples. The samples investigated had anion compositions x varying from 0 to 1 and were realized by solid state synthesis of crystalline powders or by pulsed laser deposition.[4] The absorption spectra at the Cu K-edge - both in the near-edge and extended region - prove the formation of copper oxides, primarily in the powder samples. The thin films had been capped with an Al2O3 layer in situ, as an approach to prevent further post-deposition oxidation. The analysis of the extended fine structure at the I and Br K-edges reveals a nonlinear change of the average Cu-Br and Cu-I bond lengths with composition x with consistent results for powder and thin film samples. This bond length dependence is different from that observed for group III-V and group II-VI zincblende alloys,[5] which show a linear dependence on the composition. Comparison to the bond length change in RbBr1-xIx,[6] crystallising in the rock salt structure, shows similarities that may identify this bond length bowing as a characteristic feature of group I-VII alloys. Unlike the first nearest neighbour bond lengths, the distances between second and third nearest neighbouring atoms in the CuBr1-xIx samples are consistent with previous findings for other zincblende alloys. The respective interatomic distances vary linearly with composition. Furthermore, the distances between third nearest neighbours coincide for both types of absorbing atom and follow the virtual crystal approximation. This indicates that the lattice distortions seen on a local scale due to alloy-induced lattice mismatch average out at distances larger than the second nearest neighbour shell. [1] M. Grundmann et al., Phys. Status Solidi A 210, No. 9, 1671 (2013) [2] A. Liu et al., Adv. Sci 8, 2100546 (2021) [3] N. Yamada et al., Adv. Funct. Mater. 30, 2003096 (2020) [4] M. S. Bar et al. Phys. Status Solidi RRL 2500023 (2025) [5] C. S. Schnohr, Appl. Phys. Rev. 2, 031304 (2015) [6] A. Di Cicco et al., Phys. Rev. B 65, 212106 (2002)

12:50 - 14:50

LUNCH BREAK + POSTER SESSION II

14:50 - 15:30

PLENARY 17

Julia Medvedeva

Chair: George Adamopoulos (Department of Electronic, Electrical and Systems Engineering, School of Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom)

14:50 - 15:30 Maximizing Electrical Conductivity in Amorphous Oxide Semiconductors Presenter: Juia Medvedeva (Missouri S&T) View abstract Hide abstract Abstract: Statistical methodologies that involve ab-initio non-stoichiometric liquid-quench molecular dynamics simulations, advanced time- and temperature-dependent structural analysis, and accurate hybrid-functional calculations are employed to identify, classify, and quantify various oxygen defects in prototype AOS, In2O3-x and SnO2-x. To derive the materials genome of the complex defect formation in these amorphous oxides, multiple descriptors of the defect’s local structure are considered in concert with extended bond reconfiguration that occurs to accommodate the defect in the disordered lattice. The time-resolved behavior sheds light on the defect stability, defect transformations, and defect diffusion. Matching the results with the defect’s ability to induce, compensate, or trap electronic charges, helps detangle the role of specific defects in competing mechanisms for carrier generation, charge scattering, instabilities, and optical absorption. Moreover, we further explore (pre)crystallization-mobility dependence in multi-cation AOS to accurately describe the structure-property relationship in these systems within relevant parameter space.

15:30 - 16:10

PLENARY 18

Pedro Barquinha

Chair: George Adamopoulos (Department of Electronic, Electrical and Systems Engineering, School of Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom)

15:30 - 16:10 Beyond the pixel: oxide TFTs shaping smart, sustainable systems Presenter: Pedro Barquinha Barquinha (MEON Coordinator \| CENIMAT-I3N and CEMOP-UNINOVA) View abstract Hide abstract Abstract: Thin-film transistors (TFTs) have been essential to the display industry, enabling active-matrix backplanes for individual pixel addressing. However, their unique advantages—such as ultra-low cost, mechanical flexibility, and compatibility with large-area fabrication—have also driven major advancements in flexible system-on-chip (SoC) integration over the past decade. Building on our group's extensive experience at CENIMAT\|i3N in low-temperature oxide TFTs, this presentation explores three distinct application domains where low-voltage operation and/or low power consumption were primary design constraints: • Pixel circuits for electroluminescent displays, targeting µLEDs and spin-coated quantum-dot (ELQD) technologies. These circuits were optimized for a 35 µm pixel pitch in high-resolution displays, with sub-3 V data voltages enabling microampere-range currents and fine gray level control in miniaturized light-emitting elements. • Ionizing radiation detectors, with fast response and high sensitivity to x-rays. Since the initial demonstrations of oxide TFTs as dosimeters by University of Bologna and NOVA FCT [1], more recently we optimized a bi-layer gate dielectric structure by atomic layer deposition enabling unprecedented sensitivity of (63±2) V/Gy, an order of magnitude larger than previously reported values [2]. • Energy management circuits for autonomous sensing platforms. These include an ultra-low-power wake-up timer (27 nW) [3] and voltage regulation blocks capable of supplying three independent power rails from solar energy sources. Key strategies included the use of low-dropout regulators and circuit topologies that exploit transistor leakage currents to generate ultra-low-frequency timing signals. In addition, an innovative and universal approach for integrating these flexible circuits with other components—whether on rigid or flexible substrates—will be presented. This method uses conductive adhesives with printed interconnects to link flexible circuit pads to external components, overcoming the limitations of wire bonding and direct printing techniques.

16:10 - 16:40

COFFE BREAK

16:40 - 17:20

PLENARY 19

Yiannis Deligiannakis

Chair: Nektarios Lathiotakis (National Hellenic Research Foundation)

16:40 - 17:20 Precision Engineering of Functional NanoOxides at Industrial Scale: from Lab Scale Research to the TRL ladder Presenter: Yiannis Deligiannakis (Department of Physics, University of Ioannina) View abstract Hide abstract Abstract: Metal-Oxides (MeOx) offer a fertile landscape in modern nanotechnology spanning fundamental-research topics to commercial-commodities. Current breakthrough in understanding of their physico-chemical properties that determine the desired functions of MeOx’s at the nanoscale, reveal that lattice-“nanoproperties” (quantum-size-effects, nanostrain, suface/bulk-defects, chemo-doping, spin-doping) are the key-parameters to control. In this endeavor, the transition from lab-scale to industrial-scale requires a mounting dexterity in synthesis methods that allow “precision-engineering” not just synthesis of the desired material phase.composition. Herein we discuss current advances in Flame-Spray-Pyrolysis (a-FSP) technologies1,2 as a scalable technology that allows bridging the Lab-to-Industrial production of functional nanomaterials. We position precision-engineering by FSP-technologies at the Technology-Readiness-Level (TRL) ladder, as defined by NASA and the E.U. We highlight specific examples where precision-engineering of Transparent Metal Oxides (e.g. ZrO23, Tandalum-Oxides4, SnO25) by FSP allows their transformation to functional nanoplatfroms, with emphasis on energy technologies and sensing. Within the TRL-frame of regulations, key-challenges in transforming the Lab-Scale finding to Industrial-Technology are highlighted from two perspectives: control of the desired properties and cost-efficiency.

17:20 - 18:00

PLENARY 20

Volker Sittinger

Chair: Nektarios Lathiotakis (National Hellenic Research Foundation)

17:20 - 18:00 Sputtering Technologies for the Deposition of Transparent Conductive Oxides on Large Areas Presenter: Volker Sittinger (Frainhofer IST) View abstract Hide abstract Abstract: For the deposition of transparent conductive materials (TCOs), different properties are required depending on the application. A low absorption combined with sufficient electrical conductivity is crucial. Other important properties may include temperature stability as well as humidity and heat stability. This presentation will demonstrate the production of TCOs using magnetron sputtering, as this technology is widely used in the industry and can be scaled up for large areas. A significant advantage of sputtering technology is that different generator types (DC, MF, RF, HIPIMS) can significantly influence the plasma and energy distribution at the substrate, which in turn has a major impact on film formation and its properties. Furthermore, additional parameters such pressure and substrate temperature, as well as the composition of the target during production, affect the later film properties. Examples of developments in various TCO materials and their applications in products will be presented.

18:00 - 19:00

O33-35

                                                        Chair: 

Yiannis Deligiannakis (Department of Physics, University of Ioannina)

18:00 - 18:20 Computational prediction of Cd2Sb2O7 as a candidate TCO Presenter: Peter Russell (University of Birmingham) View abstract Hide abstract Abstract: Transparent conducting oxides (TCOs) are central to the field of modern optoelectronics, displaying a unique combination of high electrical conductivity and optical transparency, with applications in touch screens, photovoltaics, LCD and OLED displays, and more. [1] The industry standard for TCOs is Sn-doped In2O3 (ITO), which displays optical transmission greater than 90%, with low resistivity and high carrier mobility. However, indium is expensive and has low earth-abundance. Alternative materials that offer comparable or superior properties using different elements are in high demand. [2,3] Recently, Sb(V) oxides have emerged as promising candidates. [4,5] Sb(V) possesses the (n − 1)d10ns0 np0 electron configuration common to many TCO cations, including In(III) in In2O3, leading to a highly disperse conduction band and a large band gap.[5] The Sb(V) oxides also display three-dimensional connectivity of SbO6 octahedra, creating electron pathways that enable high conductivity. ZnSb2O6 [4] was computationally predicted and experimentally realised as a TCO, and Sb2O5 [5] is predicted to be suitable as well, motivating further exploration of this family of materials. Cd2Sb2O7 contains Sb(V) and was flagged in a high-throughput study as having a relatively large band gap and low electron effective mass, suggesting possible transparency and conductivity. [6] However, there has been no investigation into the material’s defect chemistry. For these reasons it was decided to investigate Cd2Sb2O7 more thoroughly. The optoelectronic and structural properties of Cd2Sb2O7 were calculated using the hybrid PBE0 functional along with its intrinsic and dopant defect chemistry. Its charge transport was calculated using a combination of ab initio and semi-empirical DFT based methods. Our results suggest an optical band gap in the transparent range, a high intrinsic electron carrier concentration due to antisite defects, giving high intrinsic mobility and conductivity, and a large doping window, enabling n-type doping to further enhance conductivity. This provides further evidence for the potential of Sb(V) oxides as TCOs. [1] Lewis, B. G.; Paine, D. C. MRS Bulletin 2000, 25, 22–27 [2] Granqvist, C.; Hultaker, A. Thin Solid Films 2002, 411, 1–5 [3] Brunin, G.; Ricci, F. et al. npj Computational Materials 2019, 5 [4] Jackson, A. J.; Parrett, B. J. et al. ACS Energy Letters 2022, 7, 3807–3816 [5] Li, K.; Willis, J. et al. Chemistry of Materials 2024, 36, 2907–2916 [6] Hautier, G.; Miglio, A.; et al. Chemistry of Materials 2014, 26 (19), 5447-5458
18:20 - 18:40 Structural properties of Ga₂O₃ thin films grown via dc-pulsed magnetron sputtering using a liquid gallium target Presenter: Petr Novák (New Technologies – Research Centre, Unniversity of West Bohemia in Pilsen) View abstract Hide abstract Abstract: Our research has been dedicated to investigating the potential of dc-pulsed magnetron sputtering for the preparation of gallium oxide (Ga₂O₃) as a semiconductor material suitable for high-power and high-frequency applications. Ga₂O₃ is notable for its ultra-wide bandgap of approximately 4.8 eV, high electron saturation velocity, and its ability to withstand a high breakdown electric field of about 8 MV/cm. While epitaxial techniques for growing high-quality β-Ga₂O₃ films have advanced considerably, they still suffer from low deposition rates, which limit scalability. Our primary objective was to enhance the crystal quality of Ga₂O₃ films produced by dc-pulsed magnetron sputtering - a method known for its high deposition rate but typically challenged by the formation of well-ordered crystalline structures. An advantage of this method lies in the ability to tune oxidation conditions during growth via discharge parameters, which have a significant impact on the resulting film properties. We focused on reactive magnetron sputtering of Ga₂O₃ films from a liquid gallium metal target. The resulting film quality and characteristics were strongly influenced by several key factors, particularly the substrate temperature and the choice of substrate material—quartz, silicon, and sapphire. Our study aimed to understand how these variables affect film structure and to optimize deposition conditions for practical applications. We successfully deposited crystalline Ga₂O₃ films exhibiting a strong preferential orientation. Our experiments revealed that increasing the substrate temperature promoted crystallization, but also unexpectedly diminished the strength of the preferred orientation. To explore this further, we studied the effect of varying the pulse length in the dc-pulsed sputtering process and analyzed how it shaped the resulting film structure. These experiments were conducted across different substrates, showing that the choice of substrate plays a critical role in determining the final microstructure of the Ga₂O₃ films.
18:40 - 19:00 Exploring the Sb (V) oxides: transport and defect properties of ASb2O6 (A = Mg, Ca, Sr, Ba, Cd) Presenter: Romain Claes (University of Birmingham) View abstract Hide abstract Abstract: Transparent conducting oxides (TCOs) possess a unique combination of optical transparency and electrical conductivity, making them essential for numerous optoelectronic applications including electron transport layers in solar cells [1-3]. However, the number of oxides that are both transparent to visible light and exhibit the metallic-like conductivity required for such applications is limited to a few well-established systems. Recently, ZnSb₂O₆ and Sb₂O₅ have been proposed as promising Sb(V)-based oxides [4,5,6], demonstrating transparent conducting behavior, unusually deep band edges, and interesting band alignment for optoelectronic applications. Building on the promising results of these two systems, we extended our exploration to ASb₂O₆ compounds (A = Mg, Ca, Sr, Ba, Cd) in search of alternative candidates for practical TCO applications. Our findings indicate that CdSb₂O₆ and MgSb₂O₆ exhibit excellent transport and optical properties, positioning them as strong contenders for the future of TCOs. The defect chemistry of these two oxides was also investigated, providing valuable insights into their behavior for working applications. Finally, our work reveals a strong correlation between the atomic packing factor (a measure of how efficiently atoms are packed in a crystal structure) and carrier mobility, offering a potential approach for rapid screening of promising candidates within this class of materials.

O36-38

                                                        Chair: 

Volker Sittinger

18:00 - 18:20 Fast solution of inverse problems on IGZO transistor characterization via tandem neural network Presenter: Keisuke Ide (Institute of Science Tokyo) View abstract Hide abstract Abstract: This study develops a neural network (NN) model to solve multivalued inverse problems and applies it to the fast analysis of In-Ga-Zn-O semiconductor parameters from transistor characteristics.
18:20 - 18:40 Transparent conductive Cu diffusion barriers: A 2-dimensional combinatorial screening study on the In-Zn-O system Presenter: Stefanie Frick (Empa – Swiss Federal Laboratories for Materials Science and Technology) View abstract Hide abstract Abstract: In order to prevent Cu ingress from metal contacts into devices, the utilisation of multifunctional transparent electrodes is desirable, which can also act as Cu diffusion barriers. In this work, we employed 2-dimensional combinatorial gradient libraries to accelerate the co-optimization of electrical and optical properties as well as the Cu diffusion barrier performance by tuning cation and anion composition of In-Zn-O thin films. A promising region was identified with an electrical conductivity of 2.4*10^3 Ohm/cm and excellent diffusion barrier properties for thickness as thin as 8 nm.
18:40 - 19:00 New evaluation methods on various gas barrier performances using functional oxide films (2); Hydrogen gas barrier properties. Presenter: Taiga Kurihara (Aoyamagakuin University) View abstract Hide abstract Abstract: Hydrogen energy has numerous benefits including environmental friendliness and high energy density. Whereas some challenges such as safety concerns and hydrogen embrittlement remain. Therefore, the development of effective hydrogen gas barrier films, along with reliable evaluation methods, is essential. Conventional gas barrier evaluation techniques often face some issues such as sealing difficulties and the requirement for large-scale equipment. In this study, Pd-capped amorphous WO3 thin films, which exhibit a gasochromic response—changing color from transparent to blue—upon exposure to hydrogen were applied to evaluate the performance of gas barrier films. Using this method, comparatively reasonable barrier property of barrier films are evaluated quantitatively through simple optical transmittance measurements.　Easy and accurate evaluation of hydrogen gas barrier films and development of gas barrier films with high performance are likely to become a solid foundation of safety and efficiency use of hydrogen energy.

19:00 - 22:00

GALA DINNER

Room 1: Megas Alexandros

09:00 - 09:40

PLENARY 21

John Robertson

Chair: Pedro Barquinha Barquinha (MEON Coordinator | CENIMAT-I3N and CEMOP-UNINOVA)

09:00 - 09:40 Deep Acceptor Polarons in a-TeO2 and Hydrogen-induced Instabilities in IGZO Presenter: John Robertson (Cambridge University) View abstract Hide abstract Abstract: Calculations on amorphous eO2 find that this does not produce p-type doping.

09:40 - 10:10

I17

Nektarios Lathiotakis

Chair: Pedro Barquinha Barquinha (MEON Coordinator | CENIMAT-I3N and CEMOP-UNINOVA)

09:40 - 10:10 First-principles study of carbon-doped Cu₂O and lead-free A₂ZrX₆ defect perovskites for optoelectronic applications Presenter: Nektarios Lathiotakis (National Hellenic Research Foundation) View abstract Hide abstract Abstract: The development of new wide-bandgap semiconductors is critical for advancing transparent and optoelectronic device technologies. In this work, we report density functional theory (DFT) studies on two classes of wide-bandgap materials with enhanced potential for optoelectronic applications: (i) carbon-doped cuprous oxide (Cu₂O), and (ii) lead-free halide defect perovskites, A₂ZrX₆, where A is an organic cation and X is a halogen. Cu₂O is intrinsically a p-type semiconductor due to the presence of Cu vacancies. In this study, we examine the effects of carbon doping, considering substitutional doping at the oxygen and copper sites, as well as interstitial incorporation, using PBE and PBE+U approaches. Our results indicate an enhancement of the p-type character when carbon substitutes for an oxygen atom. In contrast, substitution of a copper atom by carbon or interstitial incorporation of carbon leads to shallow donor defect states near the conduction band minimum (CBM), thereby introducing compensating n-type conductivity. We also report results on the structural and electronic properties of lead-free, halide, “defect” perovskites of the form A₂ZrX₆. These systems hold significant potential for many optoelectronic applications due to their stability and tunable properties. Utilizing PBE and HSE06 functionals, we systematically investigate the impact of A-site cation and X-site halogen substitutions on the structural and electronic properties. Specifically, we consider A = ammonium (NH₄⁺), methylammonium (CH3NH3+), dimethylammonium ((CH₃)2NH2⁺), trimethylammonium ((CH₃)₃NH⁺), formamidinium (CH(NH2)2+), trimethylsulfonium (CH3)3S+) or phosphonium (PH₄⁺); and X = Cl⁻, Br⁻, or I⁻. Our calculations reveal that both A-site and X-site substitutions significantly affect the band gap and the lattice parameters. Increasing the size of the A-site cation generally enlarges the unit cell, while halogen electronegativity directly correlates with the band gap, yielding the lowest values for iodine-containing systems and methylammonium cation in the A-site. We predict a wide range of band gaps (from ~4.79 eV for (PH₄)₂ZrCl₆ down to ~2.11 eV for MA₂ZrI₆, using HSE06). Our first-principles predictions for C-doped Cu2O and Zr-based defect perovskites highlight their potential as next-generation semiconductors with tunable optoelectronic properties. Acknowledgment: This work was carried out within the framework of the Action 'Flagship Research Projects in challenging interdisciplinary sectors with practical applications in Greek Industry', implemented through the National Recovery and Resilience Plan Greece 2.0 and funded by the European Union - NextGenerationEU (Acronym: 3GPV-4INDUSTRY, project code: TAEDR-0537347).

10:10 - 10:30

O39

                                                        Chair: 

Pedro Barquinha Barquinha (MEON Coordinator | CENIMAT-I3N and CEMOP-UNINOVA)

10:10 - 10:30 Spray pyrolysis of ternary oxides – the case of CuxCrO2 and a-ZnSnO3 Presenter: Karsten Fleischer (Dublin City University) View abstract Hide abstract Abstract: Here we discuss several limitations and pitfalls of the spray pyrolysis method when working with ternary and quaternary compounds. Specifically, we outline how precursor solubility, thermal decomposition, but also desorption of intermediate species from the sample surface govern the spray pyrolysis growth process and can lead to significant changes between solution composition and sample composition.

10:30 - 10:50

O40

                                                        Chair: 

Pedro Barquinha Barquinha (MEON Coordinator | CENIMAT-I3N and CEMOP-UNINOVA)

10:30 - 10:50 Photocatalytic Materials for a Greener Tomorrow Presenter: Dimitra Katerinopoulou (PCN Materials) View abstract Hide abstract Abstract: The growing demand for a cleaner and more sustainable environment has driven the development and adoption of green technologies across many aspects of daily life. In particular, the need for purified air [1] and water [2]—further emphasized by the recent pandemic —has brought photocatalytic (P/C) materials to the forefront [3]. This presentation will elaborate on the general applications of photocatalytic materials and their advantages in mitigating environmental issues. Moreover, the study will be focused on the synthetic route as well as the characterization of novel core-shell structures in terms of morphological, structural and photocatalytic activation. The formation of the core-shell begins with TiO2 as the core material following the decoration, shell formation, with carbon dots (CDs) and/or silver (Ag) nanoparticles through chemical modification. The well-defined core-shell structures were confirmed via transmission electron microscopy (TEM) images and the crystalline structure was defined from X-ray diffraction (XRD) analysis. All prepared nanomaterials have been evaluated regarding their photocatalytic activity in both liquid and gaseous pollutants. Specifically, the study for the degradation of methylene blue (MB) dye was investigated under direct solar irradiation, whereas the degradation of nitrogen oxides (NOx) was tested under ultraviolet and visible light irradiation, in accordance with standard ISO procedures. This project has received funding from the European Union's Horizon Europe research and innovation programme under grant agreement No 101058422 (SUPREME). [1] Yuanchen Wei, et al., TiO2-Based Photocatalytic Building Material for Air Purification in Sustainable and Low-Carbon Cities: A Review (2023), Catalysts, 13, 1466. [2] Moreno-Vargas, et al., Photocatalysis as an Alternative for the Remediation of Wastewater: A Scientometric Review.” (2024) ChemEngineering, 8, 95. [3] Abhinandan Kumar, et al., Green aspects of photocatalysts during corona pandemic: a promising role for the deactivation of COVID-19 virus. (2022) RSC Advances, 12, 13609

10:50 - 11:20

COFFE BREAK

11:20 - 11:40

O41

                                                        Chair: 

Vassilios Binas (Aristotle University of Thessaloniki)

11:20 - 11:40 Mechanism of Epitaxial Growth of Rutile-type GeO2 by PLD Presenter: Tomoya Suzuki (Institute of Science Tokyo) View abstract Hide abstract Abstract: Wide-band-gap rutile-type GeO2 (r-GeO2) has been emerged as a promising material owing to its potential controllability of both p- and n-type conduction. Although the number of reports on epitaxial growth of r-GeO2 films has been increasing, synthesis of high-quality epitaxial films remains challenging due to competing polymorphs. In this study, we systematically investigate effects of deposition conditions on growth of GeO2 films by pulsed laser deposition (PLD). We successfully controlled the growth phase of GeO2.

11:40 - 12:00

O42

                                                        Chair: 

Vassilios Binas (Aristotle University of Thessaloniki)

11:40 - 12:00 Ambient-Stable p-Type Transparent CuI Thin-Film Transistors via Room-Temperature Pulsed Laser Deposition Presenter: Yang Chen (Felix Bloch Institute for Solid State Physics) View abstract Hide abstract Abstract: As the first discovered p-type transparent conductive material, copper(I) iodide (CuI) is considered to be among the most competitive p-type candidates in the field of transparent electronics. However, the strong compensation effect and air contamination lead to uncontrollable electrical properties. As one of the most crucial transparent devices, CuI thin-film transistors (TFTs) face the critical challenge of balancing high performance and environmental stability. Herein, we propose a room-temperature pulsed laser deposition (PLD) process for ambient-stable, high-performance p-type CuI TFTs and circuits. By introducing a buffer layer between 𝛾-CuI film and substrates, the CuI layer exhibits extremely low surface roughness (RMS < 1 nm), and the film thickness can be precisely controlled lower than 5 nm by the number of laser pulses. The free hole carrier concentration can be tuned from 10^14 cm^-3 to 10^19 cm^-3 and mobility can reach 25 cm^2 V^−1 s^−1 comparable to that of bulk CuI by controlling the compensation effect from iodine deficiency. In addition, a 200-nm-thick amorphous aluminium oxide capping layer was deposited in situ on the thin CuI film. The concentration of free hole carriers in the covered film decreased by several orders of magnitude and remained stable in the air, enabling long-term device operation under ambient conditions. The optimized TFTs exhibit a high on/off current ratio of ~10^4 with good operational stability and reproducibility. This study provides a promising pathway toward ambient-stable transparent p-type field-effect transistors for complementary electronics in combination with n-type metal-oxide devices.

12:00 - 12:30

I18

Seohan Kim

Chair: Vassilios Binas (Aristotle University of Thessaloniki)

12:00 - 12:30 Advanced Applications of Wide Bandgap Semiconductors with Hybrid Structures View abstract Hide abstract Abstract: Most transparent conducting materials are based on Sn:In2O3 (ITO). However, when deposited on flexible substrate, a single ITO coating present mechanical brittleness and poor electrical stability. A solution is enhancing amorphous structure and give them mechanical stability or using an oxide-metal-oxide (OMO) structure, typically ITO/Ag/ITO, instead of a single ITO layer. The micro quantity of hydrogen doping on ITO can stabilize amorphous structure without any deterioration in optical and electrical properties. The positive effect of hydrogen incorporated ITO has been proved with various applications which needs transparency and electrical conductivity mean time. At early stage, the hydrogen incorporated with single ITO and IZO layer, so we found that the hydrogen can suppress sub-gap level effect near 3.1 eV, and this dramatically can improve mechanical stability of amorphous thin film. Therefore, hydrogen incorporated ITO have attempted to various application, such as ITO/metal/ITO hybrid structure and surface amorphized ITO, and as a result, all of them shows improved device performances.

12:30 - 13:00

AWARDS & CLOSING REMARKS

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