Symposium CL
Development and Application of new Functional Transparent Conducting and Semiconducting Inorganic Materials
ABSTRACTS
Session CL-1 Fundamentals
CL-1:IL01 Rutile GeO2 and GeSnO2 Alloys: A New Family of UV-Transparent Conducting Oxides
E. KIOUPAKIS, Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA
I will discuss the development of rutile GeO2 and its alloys with SnO2 as a novel family of UV transparent conducting oxides. Our atomistic calculations demonstrate that these alloys exhibit superior fundamental properties that can overcome the limitations of current materials. Their band gaps are direct and dipole-forbidden, and span from 3.6 to 4.68 eV. They exhibit ambipolar dopability, with Sb, As, Ta, H, and F acting as shallow donors, while Al and Ga act as deep acceptors. The predicted carrier mobilities are high (up to 377 cm2/V s for electrons and up to 29 cm2/V s for holes), while the relatively light carrier effective masses prevent the formation of self-trapped polarons. The predicted thermal conductivity is also high (51 W/m K), a prediction that we verified experimentally in polycrystalline bulk samples. In addition, alloys of rutile GeO2 with SnO2 enable the tuning of the structural parameters to match existing substrates. We find that the energy of the conduction band of these alloys is insensitive to composition for low GeO2 mole fractions (x<40%), and results in a high electron mobility that is not affected by alloy disorder. Overall, our work demonstrates the promise of rutile GeO2-based materials for advancing the state of the art in UV transparent electrodes.
CL-1:IL03 Properties of Hydrogen in In2O3
M. STAVOLA, A. VENZIE, W.B. FOWER, Lehigh University, Bethlehem, PA, USA; L.A. BOATNER, Oak Ridge National Laboratory, Oak Ridge, TN, USA
In2O3 finds widespread application in transparent electrodes, flat panel displays, and low-emissivity windows. Interstitial hydrogen [H(i)] in In2O3 gives rise to a shallow donor that is mobile at temperatures near 100°C and that has an O-H vibrational line at 3304 cm-1 (77K) [1]. In2O3 crystals grown by the flux method have been found to contain H that is stably trapped in a form that is not readily seen by IR spectroscopy. H(i) can be dissociated from this trap by an anneal at 500°C followed by a rapid quench, a treatment that produces the O-H line at 3304 cm-1. The released H(i) then undergoes a diffusion-controlled reaction to become retrapped. Theory considers possibilities for the trapping center for H(i) and the activation barriers for H(i) motion. The kinetics of this reversible trapping process reveals a diffusion constant for H(i) that is in agreement with a recent prediction by Franckel et al.[2]. Our results show that diffusion-controlled, defect-pairing reactions involving H in transparent conducting oxides can both release H(i) upon annealing and provide a strategy to probe the diffusivity of H.
Work at LU was supported by NSF Grant 1901563.
1. A. Venzie et al., J. Appl. Phys. 137, 185703 (2025); 2. M.L.D. Franckel et al., Phys. Rev. B 110, L220101 (2024).
CL-1:IL04 Challenges and Prospects of Oxide Thin-Film Transistors for DRAM Applications
JUNGHWAN KIM, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
Oxide semiconductor thin-film transistors (Oxide TFTs) have attracted tremendous attention as promising candidates for next-generation DRAM applications, owing to their excellent BEOL compatibility and ultra-low leakage current characteristics. However, bias-temperature instabilities—such as NBTI and PBTI—remain critical challenges for Oxide TFTs. Addressing these reliability issues is essential to realize their potential in next-generation memory technology. Various strategies and channel compositions have been explored to enhance stability; among the many influencing factors, hydrogen has frequently been identified as a key contributor to device degradation. Interestingly, our recent studies have revealed a far more intricate interplay among hydrogen incorporation, fabrication processes, and channel material chemistry than previously recognized. In this presentation, we aim to revisit and critically re-evaluate the role of hydrogen in oxide semiconductors and its correlation with bias-stress stability. The discussion will cover: (i) the mechanisms of NBTI and PBTI, (ii) the role of hydrogen in oxide semiconductors, and (iii) prevalent misconceptions and analytical errors in this field.
CL-1:IL05 Controlling Point Defects and Impurities in Ga2O3 and Related Alloys
C.G. VAN DE WALLE, Materials Department, University of California, Santa Barbara, CA, USA
Exploiting the unique properties of gallium oxide for devices requires control over doping, not only in Ga2O3 itself but also in AlGaO3 alloys [1]. One needs adequate n-type conductivity, and the ability to achieve semi-insulating layers. First-principles modeling, using advanced hybrid functional calculations within density functional theory, can shed light on all aspects of this process. For donor dopants [2], we examine ionization energies [3], compensation mechanisms [4], and diffusion processes [5,6]. We also investigate formation and impact of extended defects [8]. Looking beyond current applications, we discuss the potential of Ga2O3 as a host for quantum emitters [9].
Work performed in collaboration with Y. Frodason, J. L. Lyons, G. Moody, S. Mu, H. Peelaers, L. Razinkovas, J. Speck, M. Turiansky, J. B. Varley, M. Wang, and D. Wickramaratne, and supported by AFOSR.
[1] S. Mu and C. G. Van de Walle, Phys. Rev. Mater. 6, 104601 (2022); [2] J. B. Varley et al., J. Phys. Condens. Matter 23, 334212 (2011); [3] S. Mu et al., Phys. Rev. B 105, 155201 (2022); [4] Y. K. Frodason et al., Phys. Rev. B 107, 024109 (2023); [5] M. Wang et al., Adv. Mater. Interfaces 2300318 (2023); [6] M. E. Turiansky et al., J. Appl. Phys. 137, 104401 (2025).
CL-1:IL06 Probing the Electron-phonon Interactions at Superconducting LAO/STO Interfaces via Atomic-scale Vibrational EELS
WU ZHOU, School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China
The discovery of superconductivity at the LaAlO3/SrTiO3 (LAO/STO) interface—a junction between two insulating oxides—has profoundly influenced our understanding of emergent interfacial quantum phases. In this study, we combine monochromated, momentum-resolved vibrational electron energy loss spectroscopy (vib-EELS) in scanning transmission electron microscopy, with atomic-resolution structural imaging, electronic mapping,to directly probe the lattice dynamics across LAO/STO interfaces with systematically varied carrier densities spanning the superconducting phase diagram. We discover the emergence of localized high-frequency interfacial phonons that strongly and anisotropically couple to the confined electrons, coinciding with both superconductivity and inversion symmetry breaking. These results reveal that interfacial pairing within the 2DEG at the LAO/STO interface is mediated by tunable, localized polar phonons.
Session CL-2 Material design and device development
CL-2:IL07 Development of High-performance p-type Oxide Transistors
YONG-YOUNG NOH, Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, South Korea
Developing high-mobility p-type oxide semiconductors that can be grown using silicon-compatible processes at low temperatures has remained challenging in the electronics community to integrate complementary electronics with the well-developed n-type counterparts. This presentation will discuss our recent progress in developing high-performance p-type semiconductors as channel materials for thin-film transistors. For the first part of my talk, I present an amorphous p-type oxide semiconductor composed of selenium-alloyed tellurium in a tellurium sub-oxide matrix, demonstrating its utility in high-performance, stable p-channel TFTs and complementary circuits [1]. Theoretical analysis unveils a delocalized valence band from tellurium 5p bands with shallow acceptor states, enabling excess hole doping and transport. Selenium alloying suppresses hole concentrations and facilitates the p orbital connectivity, realizing high-performance p-channel TFTs with an average field-effect hole mobility of ~15 cm2 V-1 s-1 and on/off current ratios of 10^6~10^7, along with wafer-scale uniformity and long-term stabilities under bias stress and ambient aging.
[1] A. Liu, Y.-Y. Noh et al, Nature, 629, 798–802 (2024).
CL-2:IL08 Epitaxial SrSnO3 Films with Room-Temperature Mobility Exceeding 140 cm2/Vs
B. JALAN, Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA
Exploration and advancement in ultra-wide bandgap (UWBG) semiconductors are essential for the development of next-generation high-power electronics and deep-ultraviolet (DUV) optoelectronics. In this study, we implemented a thin heterostructure design to enhance conductivity, leveraging the low electron mass and relatively weak electron-phonon coupling of the materials, while maintaining high transparency through atomically thin films. Using a SrSnO3/La:SrSnO3/GdScO3 (110) heterostructure and electrostatic gating, we successfully separated charge carriers in SrSnO3 from dopants, resulting in phonon-limited transport behavior in strain-stabilized tetragonal SrSnO3. This approach enabled modulation of carrier density from 10^18 cm-3 to 10^20 cm-3, achieving room-temperature mobilities between 40 and 140 cm2V-1s-1. First-principles calculations of phonon-limited mobility closely aligned with experimental results, suggesting the potential for even higher mobilities with increased electron density. Additionally, the heterostructure exhibited 85% optical transparency at a wavelength of 300 nm. I will discuss potential of heterostructure design in transparent UWBG semiconductor technologies, particularly for DUV applications.
CL-2:IL10 Data-Driven Design of Transparent Conductors
A. GANOSE, Imperial College London, London, UK
The discovery of new materials has driven advances in energy conversion and storage. Transparent conductors are vital technologies in photovoltaics, touch screens, and future transparent electronics. Computational materials databases provide a diverse set of potential semiconductors for screening; however, many attempts at discovery have failed to identify optically transparent and highly dopable conductors. In this talk, I present our recent attempts to circumvent these challenges. We employ high-throughput computational workflows for optoelectronic and transport properties combined with novel descriptors for transparency. Our work identifies several novel candidates with state-of-the-art performance for both n- and p-type applications.
CL-2:L11 Photophysics of Amorphous WO3 Thin Films as Transparent Conductive Oxides in the Near-IR
T. VIRGILI1, M. RUSSO2, A. VILLA2, H. CHEN2, A. TAGLIAFERRI2, A. CHIASERA3, A. CARLOTTO4, C. MANCARELLA5, D. DELLASEGA5, S.M. PIETRALUNGA1, 1CNR-IFN Milano, Milano, Italy; 2Dipartimento di Fisica, Politecnico di Milano, Milano, Italy; 3IFN – CNR, CSMFO Lab., Povo, Trento, Italy; 4Fondazione Bruno Kessler, Povo, Trento, Italy; 5Dipartimento di Energia, Politecnico di Milano, Milano, Italy
We present thin films of tungsten oxide WO3, fabricated by non-reactive RadioFrequency sputtering deposition and post-growth thermally annealed in air at 300°C for 8 hrs, that are simultaneously electrically conductive and optically transparent in the visible and near-infrared (NIR) spectrum. Their figure-of-merit as transparent-conductive-oxide (TCO) outperforms commonly used competitors (ITO, FTO, AZO) in the NIR up to 2500nm. Fabricated WO3 films are amorphous, uniform, well adherent to substrate and with subnano roughness. A thorough analysis, including SEM, EDX, XRD, Raman spectroscopy, electrical resistivity measurements, optical cw spectroscopy and spectroscopic ellipsometry, provides morphological, structural, optical and electrical information, also including some indication on chemical composition. Despite being characterized by a fully stoichiometric W/O ratio, the electrical conductivity of films is over 5000 times higher than that of crystalline WO3. By Raman spectroscopy applied to the amorphous phase and ultrafast Transient Absorption optical Spectroscopy, we analyse and discuss the nature of the defects related to W-O coordination that can be at the origin of the electrical conductivity, and their dynamical photophysics, compatible with optical transparency.
CL-2:IL12 Dopant Control of CuI for High Performance Transparent p-Type Electronics
MYUNG-GIL KIM, School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Gyunggi-do, Republic of Korea
The transparent electronic materials have been essential electronic components in large area electronics. Although there have been great success on these n-type materials, the p-type counterparts are still missing for industrial applications. We have developed transparent p-type electronics with CuI for p-type thin-film transistor (TFT) and p-type transparent conducting electrode (TCE). Initially, with the mild processing of CuI thin-film, we achieved successful control of iodine vacancy and decent TFT performance. As a continuous effort, the hole concentration suppression with Zn or Cd doping of CuI resulted high performance transparent TFT with hole mobility over 5 cm2 V-1 s-1, high Ion/Ioff of 10^7, high electrical bias stability, and circuit level integration with standar lithography compatibility. For p-type TCE, the S doping of CuI was achieved with liquid iodination process. The heavily S-doped CuI with unique liquid iodination and solution-process resulted large hole concentration of 3.25 × 10^20 cm^-3 and high conductivity of 511 S/cm with optical transmittance over 80 % at 550 nm. With the continuous development of materials and processing methods, the CuI could provide alternative solutions for high performance transparent p-type electronics.
CL-2:IL13 Single Crystal Growth and Physical Properties of r-GeO2 in Comparison with Beta-Ga2O3 and Beta-(AlxGa1-x)2O3
Z. GALAZKA, Leibniz-Institut für Kristallzüchtung (IKZ), Berlin, Germany
A demand for compact and efficient high power electronics boosts the development of ultra-wide bandgap (UWBG) oxides constituting frontier materials of 4th generation semiconductors. In addition to well studied beta-Ga2O3 and beta-(AlxGa1-x)2O3, rutile-GeO2 has recently been emerged as a UWBG oxide semiconductor with very promising properties (n- and p-type doping, high mobility, large BFOM, high thermal conductivity, low melting point). The present report will focus on bulk crystal growth of rutile-GeO2 by Top-Seeded Solution Growth, doping, epi-ready wafers, first power devices, and physical properties (structural, electrical, optical, and thermal) measured on obtained crystals [1, 2, 3 ], which will be compared with corresponding properties of bulk beta-Ga2O3 and beta-(AlxGa1-x)2O3 crystals grown by the Czochralski method. The present study points to r-GeO2 as a promising material for future power devices.
This work was funded by the Leibniz-Gemeinschaft (SAW) project under grant no. K417/2021, and Deutsche Forschungsgemeinschaft (DFG) projects under grant nos. AOBJ 681632 and AOBJ 714119.
1. Z. Galazka et al.; Phys. Status Solidi (b) 262 (2024) 2400326; 2. Z. Galazka et al.; Cryst. Res. Technol. (2025) submitted; 3. K. Tetzner et al.; Electron Device Lett. (2025) submitted.
CL-2:IL15 Ultra-High Mobility IGZO Thin-Film Transistors by Hydrogen-Defect Engineering
HYUN-SUK KIM, Dept. Energy and Materials Engineering, Dongguk University, Seoul, Republic of Korea
Oxide semiconductors are promising for next-generation electronics due to their high mobility, large-area uniformity, and low-temperature process compatibility, leading to their use in amorphous In–Ga–Zn–O (IGZO) thin-film transistors (TFTs). Although research now extends to logic and memory devices, progress remains limited by defect-related mobility loss and instability. Among various defects, hydrogen plays a key role as it easily incorporates into oxides, alters electronic states, and accelerates degradation depending on process conditions. Controlling hydrogen incorporation is therefore essential for stable, high-performance oxide TFTs. In this work, IGZO films fabricated under hydrogen-suppressed conditions exhibited reduced defect density, improved film quality, and enhanced transistor performance. With an electron-injection layer, the a-IGZO TFT achieved a mobility of 134 cm2/Vs and stable operation under bias stress and 1 MHz switching. Experimental and DFT analyses confirmed that suppressing hydrogen minimized charge trapping and stabilized device operation. These results demonstrate that hydrogen control combined with interface engineering offers a practical route to high-mobility, low-power oxide TFTs suitable for large-area display and logic integration.
CL-2:IL16 Copper Iodide - A New Material for Active p-Type Thin Film Electronics
M. GRUNDMANN, Universität Leipzig, Felix-Bloch-Institut für Festkörperphysik, Leipzig, Germany
Elemental semiconductors, initially germanium and later silicon, have long been the dominant materials in the electronics and photovoltaic industries. More recently, diamond has attracted renewed interest, particularly in the fields of power electronics and quantum computing. Meanwhile, compound semiconductors, particularly III-V materials, have become the leading choice for photonic applications like LEDs and lasers. Additionally, II-VI semiconductors serve critical niche markets, including infrared technologies and thyristors. We explore the promising applications and recent advancements in halide semiconductors, specifically copper iodide, a naturally p-type, wide-bandgap I-VII compound, along with its related alloys. The primary focus is on utilizing this semiconductor for transparent thin-film p-type and complementary electronics. As with any semiconductor material, key challenges for its technological viability include achieving high-quality bulk crystal and thin-film growth, precise control of conductivity through doping, effective surface passivation, long-term stability, reliable ohmic contacts, and the development of diode and transistor devices. We report on our recent progress regarding intrinsic thin films, controlled doping and the first CuI thin film transistors that are - together with suitable passivation layers - stable against environmental conditions.
CL-2:IL17 Engineered Transparent Conductive Oxides: From Structure To Performance
P. LLONTOP, M. MORALES-MASIS, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands
Transparent conductive oxides (TCOs) are key to modern photovoltaics, from single-junction perovskites to tandem solar cells. This talk explores how tuning microstructure and processing can enhance TCO electrical performance while using low-damage techniques such as room-temperature pulsed laser deposition (PLD) to preserve delicate underlying layers in device stacks. We illustrate these effects with investigations of Zr-doped In2O3 and SnO2 films. Zr-doped In₂O₃ deposited in an 80% Ar / 20% O2 atmosphere achieves the highest mobility after solid-phase crystallization at 200 °C, providing optimal high-performance electrodes. Films grown at 50% Ar / 50% O2 show higher as-deposited mobility but minimal improvement after annealing, making them suitable for integration on sensitive layers. SnO2 films deposited under optimized conditions combine low resistivity with mobility doubling after annealing at 300 °C. When applied on tunnel oxide passivated Si layers, they cause no damage, maintain low contact resistance, and support perovskite growth, highlighting their potential as In-free recombination layers in perovskite/Si tandem cells. These results show how controlled microstructure and processing yield high-performance TCOs tailored for next-generation photovoltaics.
CL-2:IL18 Transparent Electrodes with Interplay of Conductivity and Transparency for Flexible Electronics
HYEOK KIM, University of Seoul, Seoul, South Korea
Transparent electrodes represent a critical enabling component for next-generation flexible and wearable electronics, where high optical transparency must coexist with superior electrical conductivity and mechanical resilience. In this talk, we present our recent advances in designing and integrating oxide-based, hybrid, and nanostructured electrodes that balance these conflicting requirements. By combining solution-processed materials such as Ag Nanowire, conducting polymer and conducting/semiconducting oxide nanoparticles, we demonstrate electrodes that maintain over 90 % optical transmittance while achieving sheet resistances below 20 Ω/sq. Particular emphasis is placed on the interplay between microscopic structure, carrier transport, and optical scattering, revealing design principles that extend beyond conventional indium tin oxide. This work demonstrates the applications in flexible displays, energy devices, and bio-integrated sensors, illustrating the practical impact of these transparent conductors. The insights gained provide a pathway toward robust, cost-effective, and sustainable transparent electrode technologies, addressing key bottlenecks in the commercialization of flexible electronics.
CL-2:L19 Fabrication of p-type Copper Oxides Doped by Nitrogen and Boron Using High-power Impulse Magnetron Sputtering
J. REZEK, N. KUMAR, J. KOLOROS, P. BAROCH, Department of Physics and NTIS - European Centre of Excellence, University of West Bohemia in Pilsen, Czech Republic
Currently, one of the topics in materials science is the research on finding sufficiently efficient p-type transparent conductive oxides (TCOs). Currently, there is no p-type material with the same optoelectric properties as its n-type counterpart, especially in terms of electrical conductivity. This problem needs to be solved to create efficient p-n junctions, which are necessary for applications in transparent electronics or for more efficient solar cells. In this work, we investigate the doping of copper oxides (Cu2O, CuO) with nitrogen or boron using high-power impulse magnetron sputtering (HiPIMS). It will be demonstrated that the HiPIMS method is highly suitable for tuning the electrical and optical properties of layers, and that it enables an increase in electrical conductivity by several orders of magnitude compared to undoped oxides. Special attention will be paid to clarifying the relationships between the discharge plasma parameters and the structure, composition and properties of the prepared layers.
CL-2:L20 Sustainable Thin-film Temperature Sensors on Shellac Coated Wood Substrates
F. MASOUMI, R. ZAMBONI, N. MÜNZENRIEDER, Faculty of Engineering, Free University of Bozen-Bolzano, Bozen-Bolzano, Italy; A. NIJKOOPS, Laboratory of Food Process Engineering, Wageningen University and Research, Wageningen, the Netherlands
The integration of electronic functionality into natural and renewable substrates represents an important step toward sustainable device technologies. In this work, thin-film temperature sensors are fabricated on shellac-coated wood substrates using two complementary approaches: direct vacuum deposition of metallic layers and sacrificial-layer-free transfer of thin-film devices. This combination demonstrates the feasibility of integrating different thin-film processing techniques with bio-derived materials. The comparably large surface roughness >10 µm of the natural wood veneer substrate can be reduced by a shellac coating which simultaneously enhances compatibility with both vacuum- and solution-based processes. Furthermore, the substrate thickness of ≈0.5 mm ensures its mechanical flexibility. shadow masking on these substrates was used to fabricate Silver based resistive temperature detectors (RTDs) and amorphous InGaZnO (IGZO) based thermistors. All devices were characterized over multiple thermal cycles. The RTDs exhibit near-linear responses with sensitivities up to 0.2 % °C⁻¹ and mechanical stability under bending. These results illustrate a pathway toward sustainable, and visually unobtrusive thin-film electronics integrated into natural materials for smart environments.
Session CL-3 Applications
CL-3:IL21 Fully Patterned Solution-based Zinc-tin Oxide Electronics
J. DEUERMEIER1, C. SILVA1, R. MARTINS1, L. MENDES2, J. VAZ3, G. MILANO4, M. ROSERO-REALPE5, E. FORTUNATO1, R. MARTINS1, E. CARLOS1, A. KIAZADEH1, 1CENIMAT|i3N, Department of Materials Science, School of Science and Technology, NOVA University Lisbon and CEMOP/UNINOVA, Caparica, Portugal; 2Instituto de Telecomunicações, Lisbon and Instituto Politécnico de Leiria, Leiria, Portugal; 3Instituto de Telecomunicações, Lisbon and Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal; 4Advanced Materials Metrology and Life Science Division, INRiM, Torino, Italy; 5Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy
Achieving sustainability in modern electronics requires the development of active components that combine functionality with environmental responsibility. However, using abundant semiconductors and additive manufacturing does not need to compromise the electric performance or applicability to advanced operation schemes. Here, we show the versatility of solution-based zinc-tin oxide (ZTO) with record-breaking diode characteristics and in materia reservoir computing functionality. The 25 μm² ZTO diodes exhibit best-in-class results for vertically stacked solution-based oxide diodes, such as reverse currents below 1 pA, rectification ratios exceeding nine orders of magnitude, and intrinsic cut-off frequencies above 40 GHz.[1] The memristors with inkjet-printed ZTO achieve 89.4% accuracy and 86.5% by processing 4-bit and 5-bit input temporal sequences for MNIST handwritten digit classification.[2] All devices were fully patterned and processed up to 250°C for compatibility with flexible substrates.
1. Silva, C. et al. High-frequency solution-based ZTO Schottky diodes. (under review, 2025); 2. Azevedo Martins, R. et al. Printed Zinc Tin Oxide Memristors for Reservoir Computing. Advanced Intelligent Systems https://doi.org/10.1002/aisy.202500450 (2025).
CL-3:IL22 Bioinspired Flexible Sensors for Human-machine Interfaces
HYUNHYUB KO, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
Inspired by the structure and function of biological systems, we present several structural design strategies for micro/nanostructured polymer composites as soft sensors with excellent sensing capabilities and their applications in wearable devices and human-machine interfaces. First, inspired by the fingertip skin structure and function, we develop multifunctional electronic skins capable of differentiating various mechanical stimuli (normal, shear, stretching, bending), static and dynamic pressure, and temperature with high sensitivities. Second, inspired by the sound frequency tunability of the cochlea, we demonstrate frequency-selective acoustic and haptic sensors for dual-mode human–machine interfaces based on triboelectric sensors with hierarchical ferroelectric composites. Finally, mimicking stimuli-responsive color changing structures found in biological systems, we present colorimetric tactile sensors that can monitor external forces based on the color change signals.
CL-3:IL23 β-Ga2O3 Epitaxial Growth and Device Technologies for Power and RF Electronics
M. HIGASHIWAKI, Osaka Metropolitan University, Sakai, Osaka, Japan; Y. KUMAGAI, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan
Wide bandgap semiconductor devices including SiC and GaN have been intensively developed to address shortcomings of Si devices. Recently, ultrawide bandgap semiconductors with bandgap energies of over 4 eV represent an emerging research field. Among them, Ga2O3 is recognized as one of the most promising candidates. β-Ga2O3 having a bandgap energy of 4.5 eV and a maximum breakdown electric field of over 7 MV/cm is the most stable polymorph, and its single-crystal bulks can be synthesized by melt growth methods. From the excellent electrical properties originated from the extremely large bandgap and the high mass production capability of wafers manufactured with the melt-grown bulks, β-Ga2O3 field effect transistors and diodes have been actively developed for future-generation power switching and RF applications [1]. In this lecture, after a brief introduction to physical properties of β-Ga2O3, our current research and development on Ga2O3 epitaxial growth and device technologies will be given.
The works were supported by MIC under a grant entitled “R&D of ICT Priority Technology (JPMI00316): Next-Generation Energy-Efficient Semiconductor Development and Demonstration Project (second period) (in collaboration with MOEJ).
[1] M. Higashiwaki, IEEE Electron Devices Magazine 2, 42 (2024).
CL-3:IL24 CVD Based Functionalized Parylene Layer as a Flexible Gate Dielectric for Oxide Transistors
KYUNG JIN LEE, Department of Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon, Republic of Korea
Introduction of thin film polymer into specific surfaces has been of special interests in last years, and various methods have been developed so far. Among them, parylene is one of attractive polymeric thin film having thin, pin-hole free, and high-quality characteristics with solvent-less procedure (chemical vapor polymerization). Herein, I would like to introduce functionalized poly-paracyclophane (known as parylene) and their applications especially in potential dielectric or cover layer of stretchable and flexible devices. In particular, the parylene layer having specific organic moiety can not only provide photopatternable dielectric layer (with parylene-OH) but also suggest dielectric layer with tunable dielectric constant via surface treatment through click reaction (with parylene ethynyl).
CL-3:IL25 Oxide Electronics in Unconventional, Flexible and Natural Substrates
N. MÜNZENRIEDER, Faculty of Engineering, Free University of Bozen-Bolzano, Bolzano, Italy
Amorphous Indium Gallium Zinc Oxide (IGZO) thin films have emerged as key materials for flexible and sustainable electronics, owing to their high electrical performance, optical transparency, and compatibility with low-temperature processing. In addition, IGZO’s partial water solubility enables environmentally benign fabrication and recycling strategies. Here, the direct integration of IGZO thin-film transistors (TFTs) and thermistors onto a broad range of unconventional substrates by vacuum deposition, lithography, and shadow masking is presented. The investigated substrates include engineering polymers such as PEEK, Parylene, TAC, PDMS, PI, FEP, and PU, as well as natural and composite materials including buffalo horn, fruit paper, brick, mother of pearl, and stone paper. The resulting TFTs exhibit effective mobilities up to 15 cm²/Vs, threshold voltages below 1.5 V, and subthreshold swings down to 120 mV/dec, maintaining functionality under mechanical deformation. Thermistors display sensitivities of approximately –0.2 %/°C and complete water solubility. The results demonstrate the versatility of oxide electronics on unconventional substrates and their potential for sustainable, bio-integrated, and recyclable device technologies.
CL-3:IL26 Unlocking Sustainable Iontronics: Neuromorphic e-SKIN
DO HWAN KIM, Dept. of Chemical Engineering, Hanyang University, Seoul, Republic of Korea
An iontronic-based artificial tactile nerve is a promising technology for emulating the tactile recognition and learning of human skin with low power consumption. However, its weak tactile memory and complex integration structure remain challenging. In this talk, we explore the significance of ion dynamics in sustainable solid-state gel electronics for neuromorphic e-SKIN applications such as tactile perception, biochemical and electrophysiological sensing, neural interfaces, and therapeutic treatments. We conclude with future perspectives and challenges in gel-based electronic devices, highlighting the need for ongoing innovation in iontronic materials to further enhance the integration of these technologies in the versatile fields. Additionally, we aim to extend our discussion to the emulation of biological perception via artificial synapses, concluding with future perspectives and challenges in neuromorphic system development.