The β-Ga2O3/Al2O3 gate-dielectric interface is systematically investigated following various oxidative surface treatments via in situ physical characterization and ex situ electrical device characterization. Although β-Ga2O3 surfaces pretreated with established oxidizing techniques (namely, O2 plasma, ultraviolet-ozone [UV-O3], and O2 annealing) demonstrate a significant reduction in carbonaceous species via in situ X-ray photoelectron spectroscopy (XPS), capacitance-voltage (C-V) profiling of the corresponding metal-oxide-semiconductor (MOS) capacitors reveals no commensurate improvement in electrical performance. This discrepancy is attributed to the readsorption of carbonaceous species, presumably derived from residual metal-organic precursors, onto the semiconductor surface during thermal equilibration within the atomic layer deposition (ALD) chamber. In this work, we report an integrated O3 prepulsing strategy designed to decontaminate the β-Ga2O3 surface immediately before dielectric deposition, thereby minimizing the exposure window to deleterious carbonaceous species within the ALD ambient. Compared to the alternative pretreatments, O3 prepulsing yields superior surface passivation and decontamination, resulting in marked improvements in flat-band characteristics, interface trap density, and frequency dispersion. O3 prepulsing is compatible with standard ALD systems and provides a practical, scalable solution for high-quality β-Ga2O3 gate-oxide engineering.

A ( (-)201 )-oriented beta-Ga2O3 (beta-gallium oxide) single crystal wafer, 2 in. in diameter, was diced into 5 & times; 5 mm(2) specimens for surface chemical analysis using x-ray photoelectron spectroscopy (XPS). To ensure accurate surface characterization, both ex situ and in situ pretreatment methods were employed to effectively remove surface contaminants. XPS data collection included a comprehensive survey spectrum and high-resolution core-level scans of Ga 2p, Ga 3s, Ga 3p, Ga 3d, O 1s, and C 1s, along with valence band spectra and Ga LMM and O KLL x-ray induced Auger electron spectroscopy (XAES) transitions. The oxidation state identified in all gallium and oxygen photoelectron lines corresponds to Ga3+, indicating the presence of the beta-Ga2O3 phase. Additionally, organic oxides and hydrocarbons were detected after 300 degrees C UHV annealing, which indicates the presence of strongly bonded species and an elevated number of dangling bonds on the ( (-)201 ) surface. The Ga and O Auger features further corroborate the oxidation state assignments and offer additional insight into the surface chemical environment of the beta-Ga2O3 specimens.

A 2-in. beta-Ga2O3 (beta-gallium oxide) single-crystal wafer of (001) orientation was diced into 5 & times; 5 mm(2) specimens, and its surface was characterized via x-ray photoelectron spectroscopy (XPS). Both ex situ and in situ pretreatments were conducted prior to XPS to eliminate surface contamination. Comprehensive spectra were acquired, including a wide survey scan and high-resolution core-level scans of Ga 3d, Ga 3p, Ga 3s, Ga 2p, O 1s, and C 1s, along with the valence band spectra and Ga LMM and O KLL x-ray induced Auger electron spectroscopy (XAES) transitions. The oxidation state observed across all gallium and oxygen core levels corresponds to Ga & sup3;(+), which, when combined with the quantitative analysis results, supports the presence of a stoichiometric beta-Ga2O3 phase. Carbon contamination was found to be negligible, indicating a clean surface with minimal adventitious carbon. The presence and spectral features of the Ga and O Auger lines further substantiate the oxidation state assignments and provide complementary insights into the surface chemical environment.

The surface chemistry of a (010)-oriented beta-Ga2O3 (beta-gallium oxide) single crystal was investigated using x-ray photoelectron spectroscopy (XPS). A 2 in. wafer was sectioned into 5 & times; 5 mm(2) specimens, and both ex situ and in situ surface cleaning procedures were incorporated to minimize contamination prior to analysis. XPS measurements included a wide energy survey and high-resolution scans of Ga 2p, Ga 3s, Ga 3p, Ga 3d, O 1s, and C 1s core levels, as well as the valence band region and Ga LMM and O KLL x-ray induced Auger electron spectroscopy (XAES) transitions. The spectra consistently revealed Ga3+ as the only oxidation state, in agreement with the expected chemical state for beta-Ga2O3. Additionally, the composition derived from the quantitative analysis indicates the existence of stoichiometric Ga2O3. Carbon was present only at trace levels, reflecting an effectively cleaned surface. The Auger transitions of Ga and O provided complementary confirmation of oxidation states and contributed to a more comprehensive understanding of the surface electronic structure.

We have investigated the properties of the Au/Cr/HfO2/beta-Ga2O3( 2(-)01) MOS (metal-oxide-semiconductor) system after annealing (450 degrees C) in different ambient conditions (forming gas, N-2, and O-2). Defect properties have been analyzed using an approach combining experimental impedance measurements with physics-based simulations of the capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics of beta-Ga2O3/HfO2 MOS capacitors. The analysis demonstrates that the electrically active defects are not confined to the beta-Ga2O3/HfO2 interface but are comprised of two defect bands in HfO2 characterized by thermal ionization energies of similar to 1.1 eV (acceptor-like) and similar to 2 eV (donor-like) attributed to a polaronic self-trapping state and an oxygen vacancy in HfO2, respectively. The adopted methodology also enabled the extraction of the spatial distribution of defects across the HfO2 thickness and Cr/HfO2 interface. The high concentration of oxygen vacancies close to the Cr/HfO2 interface extracted from experimental and simulated electrical data is confirmed by in situ XPS analysis, which shows how Cr is scavenging oxygen from the HfO2 and creating the donor band confined near the Cr/HfO2 interface. This donor band density is observed to be reduced after annealing, and the reduction is not ambient dependent. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

In this study, we investigate IGZO TFT reliability under different positive bias stress voltages and propose an interstitial hydrogen diffusion mechanism as a major contributor to threshold voltage (VT) shift. By combining device fabrication and measurements coupled with TCAD and density functional theory (DFT) modeling of donor and acceptor defects in the IGZO channel, the effect of these defects on device threshold voltage instability was evaluated., where the observed VT shift characteristics are attributed to interactions between diffused hydrogen atoms into the IGZO channel., and their influence on defect densities in the channel.

We have investigated the properties of the \b{eta}-Ga2O3(-201)/HfO2/Cr/Au MOS (metal-oxide-semiconductor) system after annealing (450oC) in different ambient conditions (forming gas, N2 and O2). Defect properties have been analyzed using an approach combining experimental impedance measurements with physics-based simulations of the capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics of \b{eta}-Ga2O3/HfO2 MOS capacitors. This approach enabled us to detect two defect bands in HfO2 characterized by thermal ionization energies of ~1.1eV (acceptor-like) and ~2eV (donor-like) attributed to a polaronic self-trapping state and an oxygen vacancy in HfO2, respectively. This study demonstrates how thermal treatments affect the energy distributions and densities of the observed defects. The adopted methodology also enabled the extraction of the spatial distribution of defects across the HfO2 thickness and Cr/HfO2 interface. The high concentration of oxygen vacancies close to the Cr/HfO2 interface extracted from experimental and simulated electrical data is confirmed by in-situ XPS analysis which shows how Cr is scavenging oxygen from the HfO2 and creating the donor band confined near the Cr/HfO2 interface. This donor band density is observed to be reduced after annealing as per simulation and unchanged for different annealing conditions. We speculate this may be due to the formation of dense films and polyforms of HfO2 under different ambient as revealed by high-resolution TEM images.

We have investigated the properties of the β-Ga_2O_3(2̅01)/HfO_2/Cr/Au MOS (metal-oxide-semiconductor) system after annealing (450^∘C) in different ambient conditions (forming gas, N_2 and O_2). Defect properties have been analyzed using an approach combining experimental impedance measurements with physics-based simulations of the capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics of β-Ga_2O_3/HfO_2 MOS capacitors. This approach enabled us to detect two defect bands in HfO_2 characterized by thermal ionization energies of 1.1eV (acceptor-like) and 2eV (donor-like) attributed to a polaronic self-trapping state and an oxygen vacancy in HfO_2, respectively. This study demonstrates how thermal treatments affect the energy distributions and densities of the observed defects. The adopted methodology also enabled the extraction of the spatial distribution of defects across the HfO_2 thickness and Cr/HfO_2 interface. The high concentration of oxygen vacancies close to the Cr/HfO_2 interface extracted from experimental and simulated electrical data is confirmed by in-situ XPS analysis which shows how Cr is scavenging oxygen from the HfO_2 and creating the donor band confined near the Cr/HfO_2 interface. This donor band density is observed to be reduced after annealing as per simulation and unchanged for different annealing conditions. We speculate this may be due to the formation of dense films and polyforms of HfO_2 under different ambient as revealed by high-resolution TEM images.

Two-dimensional (2D) semiconductors have received a lot of attention as the channel material for the next generation of transistors and electronic devices. On the other hand, insulating 2D gate dielectrics, as possible materials for gate dielectrics in transistors, have received little attention. We performed an experimental study on bismuth oxychloride, which is theoretically proposed to have good dielectric properties. High-quality bismuth oxychloride single crystals have been synthesized, and their high single crystallinity and spatial homogeneity have been thoroughly evidenced by x-ray diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, transmission electron microscopy (TEM), and scanning TEM studies. We then mechanically exfoliated high-quality BiOCl crystals to fabricate metal-insulator-metal (MIM) capacitors and measured the dielectric properties at various frequencies and different thicknesses. We found that BiOCl exhibits an out-of-plane static dielectric constant up to 11.6, which is 3 times higher than 2D hexagonal boron nitride making it a suitable candidate for 2D dielectrics. We also carried out cross-section TEM studies to look into the MIM interface and provide some future directions for their integration with metal-dielectric interfaces and possibly with other 2D devices.

This study presents a set of standardized test structures designed to systematically investigate the influence of gate dielectric materials on depletion-mode GaN/AlGaN/GaN MOS-HEMTs. By employing D-mode HEMTs, transfer length method (TLM) structures, and MOS capacitor structures, comprehensive characterization of essential device parameters, including maximum drain current (I-D,I-MAX), threshold voltage (V-TH), transconductance (G(M,MAX)), subthreshold swing (SS), interface trap density (D-IT), and field-effect mobility (mu(FE)) was conducted. Three distinct gate dielectrics (HfO2, Al2O3, and SiNx) were analyzed, revealing clear correlations among dielectric properties, interface quality, and overall device performance. The integrated approach demonstrated the importance of optimized dielectric deposition and interface engineering, highlighting that despite the superior capacitance of high-kappa dielectrics like HfO2, interface quality critically influences device performance. This test-bed approach offers a powerful platform for systematically investigating and optimizing gate dielectric integration processes, advancing the development of high-performance GaN-based MOS-HEMT technologies.

Surface Acoustic Wave (SAW) devices, particularly those made of Lithium Niobate (LiNbO3), are extensively used in telecommunications and microfluidic applications. This work describes the fabrication of a LiNbO3-based SAW test structures using maskless photolithography for rapid device dimension changes as well as introduces a cost-effective technique to solder Sub-Miniature version A (SMA) connectors to delicate substrates such as LiNbO3-based SAWs, without the need to fully create printed circuit boards. The SMA connected device facilitated improved characterization results compared to simple copper tape connections. The characterization accuracy is then validated through simulation.

This study presents a detailed analysis of total ionizing dose (TID) effects induced by X-ray irradiation on zinc oxide (ZnO) and Indium-Gallium-Zinc Oxide (IGZO) thin-film transistors (TFTs). We performed a comprehensive evaluation that includes structural, morphological, and electronic characterizations to assess the impact of X-ray irradiation on the inherent properties of metal-oxide-semiconductor layers within the TFTs. Comparative assessments following variable dose exposures provide insights into the degradation mechanisms and emphasize the differential resilience of ZnO and IGZO-based devices to radiative environments.

Abstract-Correlated electron RAM (CeRAM) device test structures utilizing C-doped NiO were fabricated and electrically characterized to determine functionality in extreme environments. CeRAM devices were demonstrated to repeatedly cycle at temperatures up to 200°C while maintaining a substantial memory window of over 1000 x. Careful selection of compliance current when sweeping the high resistance state (OFF) is required for optimal device performance. The presence of a temperature dependent leakage current in the OFF state results in reducing OFF resistance at elevated temperatures.

This paper reports modeling and experimental studies on the impact of dopant, defects, and mobility in W doped amorphous In 2 O 3 for BEOL transistors. W doping in amorphous In 2 O 3 is shown to suppress oxygen vacancy (Vo) and to donate electrons. Fundamental material parameters, including defect gap states and carrier mobilities, are characterized by a combined DFT modeling and experiment. The results provide useful information for developing an IWO device compact model, and further improving IWO channel device performance.

A low-temperature and straightforward fabrication process for ZnO thin-film transistors (TFTs) with near-zero aging and negligible instability enabled by using an ultrathin oxide as a top-passivation layer is demonstrated. The process features bottom-gate top-contacts ZnO TFTs with ultrathin HfO2 or Al2O3 as passivation layers on top of the TFT followed by post-fabrication annealing (PFA). Devices with ultra-thin capping films of Al2O3 followed by a 150 °C PFA show threshold voltage shift (ΔVTH) of <1% after bias stress and negligible shift after aging. The devices show saturation threshold voltage (VTH-SAT) of 2.70 V, saturation mobilities larger than 10 cm2/V·s, and current ION/IOFF ratios >106. On the contrary, devices without nanofilm show similar performance to those with Al2O3 but show more considerable instability to aging and bias stress (ΔVTH > 5%). Also, devices with HfO2 as a capping layer shows severe instability (ΔVTH > 40%). A degradation mechanism to explain the improved aging and reliability performance is also discussed.

Gallium oxide (β-Ga2O3) is becoming a popular material for high power electronic devices due to its wide bandgap and ease of processing. In this work, β-Ga2O3 substrates received various annealing treatments before atomic layer deposition of HfO2 and subsequent fabrication of metal–oxide–semiconductor (MOS) capacitors. Annealing of β-Ga2O3 with forming gas or nitrogen produced degraded capacitance–voltage (C–V) behavior compared to a β-Ga2O3 control sample with no annealing. A sample annealed with pure oxygen had improved C–V characteristics relative to the control sample, with a higher maximum capacitance and smaller flat-band voltage shift, indicating that oxygen annealing improved the C–V behavior. X-ray photoelectron spectroscopy also suggested a reduction in the oxygen vacancy concentration after O2 annealing at 450 °C, which supports the improved C–V characteristics and indicates that O2 annealing of β-Ga2O3 may lead to better MOS device performance.

CeRAM devices were fabricated and electrically characterized following x-ray irradiation exposure for the purpose of investigating device reliability and operation in harsh environments. CeRAM were subjected to a total ionizing dose (TID) of up to 1 Mrad, which was found to induce resistance switching (RS) of the memory state. TID was determined to have no impact on RS parameters, including both switching voltages and resistance levels.

A novel photodetecting device architecture that combines the optoelectronic property advantages of a perovskite and the amplification properties of a Si metal–oxide–semiconductor field‐effect transistor (MOSFET) to innovate a photodetecting system with ultrahigh sensitivity, especially in low‐light intensity, is demonstrated. This perovskite‐based MOSFET photodetector (PM‐PD) can respond as low as 116 nW cm−2 with extremely high responsivity 4200 A W−1. The perovskite is part of the gate dielectric to modulate the MOSFET drain current when the light intensity is changed. A direct bandgap, organic–inorganic hybrid halide perovskite with a large optical absorption coefficient, can enhance photodetector performance. However, perovskite materials are not good conductors for transporting photogenerated electrons and holes compared with single‐crystal silicon. Therefore, the perovskite was utilized as a dielectric where the capacitance is used instead. In the proposed PM‐PD architecture, changing the width‐to‐length (W/L) ratio of perovskite capacitor electrodes, can modulate the dark current from picoamperes to microamperes providing a tunable parameter for optimizing photodetecting performance. Furthermore, the capacitance of the perovskite can be modulated by frequency, which facilitates matching the capacitance of perovskite and MOSFET gate oxide—another important requirement for optimal photodetecting performance. Finally, our novel PM‐PD is commensurate with potential 3D monolithic integration.

The semiconductor industry is striving towards stacked functionality on underlying integrated circuits to achieve monolithic 3D integration. This could require relatively low temperature, oxide-based semiconductor device fabrication in the backend of line (BEOL) to facilitate specialized and/or new on-chip functionalities. Therefore, low-temperature IGZO deposited at different pressures in thin-film transistors (TFTs) were investigated. Deposition pressures from 5 mTorr to 30 mTorr were compared using I-V, C-V, and physical characterization. The results determined that a 20 mTorr IGZO deposition pressure resulted in the best overall TFT performance.

Lead-free 0.4(BiFe0.995Mn0.005O3)–0.6(SrTiO3) thin films were deposited on boron-doped silicon (p-Si) through pulsed laser deposition. The effect of different deposition pressures ranging from 4.66 × 10− 5 to 13.33 Pa was evaluated, with a corresponding deposition temperature of 700 °C. A conventional lithography process was used to define vertical metal–insulator–metal structures, and the electrical characteristics of these structures were evaluated. The results revealed that as the densification is improved, the leakage current is enhanced and the dielectric constant decreased with the decrease in thickness and increase in deposition pressure. The curve of the current density as a function of the applied electric field exhibited a rectifying effect, with a difference of nearly two orders of magnitude in the current with a forward bias compared to that with a reverse bias. The leakage current mechanisms in metal–ferroelectric–semiconductor structures were investigated as well. The main electrode-limited conduction mechanisms were Schottky emission and Fowler–Nordheim tunneling; the bulk-limited mechanisms were ohmic conduction under low applied electric fields and space charge-limited conduction (SCLC) under high electric fields. The SCLC model was used to calculate the total trap-state density (Nt) at room temperature; Nt was higher in the films deposited under higher pressures.