Spotlights

Physical reservoir computing (PRC) is useful for edge computing, although the challenge is to improve computational performance. In this study, we developed an inverted input method, the inverted input is additionally applied to a physical reservoir together with the original input, to improve the performance of the ion-gating reservoir. The error in the second-order nonlinear equation task was 7.3 × 10⁻⁵, the lowest error in reported PRC to date. Improvement of high dimensionality by the method was confirmed to be the origin of the performance enhancement. This inverted input method is versatile enough to enhance the performance of any other PRC.

We study the terahertz (THz) magnetic field pulse enhanced by a spiral-shaped antenna resonator (SAR). We deposit the SAR on the surface of a terbium-gallium-garnet crystal, which has a large Verdet constant, and measure the Faraday rotation angle for strong THz pulse excitation by magneto-optical sampling (MOS) with NIR light. The determined magnetic field strength and field-enhancement spectrum are consistent with the theoretical predictions. This first report of the detection of a Tesla-class picosecond magnetic field pulse by MOS is expected to be useful in research on the control of magnetization in spintronic devices.

MEMS resonant sensing devices require both HF (f) and low dissipation or high quality factor (Q) to ensure high sensitivity and high speed. In this study, we investigate the resonance properties and energy loss in the first three resonance modes, resulting in a significant increase in f‧Q product at higher orders. The third order resonance exhibits an approximately 15-fold increase in f‧Q product, while the Q factor remains nearly constant. Consequently, we achieved an ultrahigh f‧Q product exceeding 10¹² Hz by higher-order resonances in single-crystal diamond cantilevers.

Ce:Li₆Y(BO₃)₃ (LYBO) is a well-known candidate for thermal neutron detection with a very high Li concentration (3.06 × 10²²/cm³). So far, as-grown crystals exhibit a milky appearance that compromises their performance as scintillators. Current work demonstrates, for the first time, the growth of scattering-free undoped and Ce-doped LYBO by a thermal quenching process. The origin and features of the scattering centers are investigated in detail. Furthermore, the annealing treatment for the scintillation activation is studied, finding that the reduction in oxygen vacancies is mandatory. Under thermal neutron irradiation, the annealed scattering-free Ce:LYBO single crystal achieves a record-high light yield of 6200 ph/n in a single decay with a lifetime as short as 24 ns.

Thermal healing of focused ion beam-implanted defects in GaN is investigated by off-axis electron holography in TEM. The data reveal that healing starts at temperatures as low as about 250 °C. The healing processes result in an irreversible transition from defect-induced Fermi level pinning near the VB toward a midgap pinning induced by the crystalline-amorphous transition interface. Based on the measured pinning levels and the defect charge states, we identify the dominant defect type to be substitutional carbon on nitrogen sites.

The Si-nano dot substrates formed using the ultrathin silicon oxide films were applied to fabricate CaSi₂ films. The CaSi₂ formed by this process was identified as the metastable phase 2H as the main component, and the 1H structure existed partially at the grains of the 2H phase. Although no experimental reports exist for the formation of 2H-CaSi₂ crystal, the Si-nano dot substrates are considered as the high-entropy substrate to form the metastable phases. We experimentally determined the lattice parameter of the 2H phase by the annular dark field–scanning transmission electron microscopy observations using the Si as an internal standard sample.

We have designed a directly-displayed refractive index detection chip based on rotating metal nanopillar arrays. When environments fluctuate, it can focus the detection signal on different directions as designed. This refractive index compass can be easily attached to conventional portable devices due to its compact structure, and has a wide adjustable working range. By utilizing multiple phase information contained in a single metasurface, the environmental refractive index on surface or solution concentration can be accurately determined by observing the position and color of the focal point under dual wavelength common incidence.

A well-ordered molecular arrangement is a necessary condition for "band transport" in molecular semiconductor materials, and thus it is important for donor–acceptor molecular junctions for applications in advanced organic optoelectronic devices. In this study, the heteroepitaxial growth of an acceptor material C₆₀ on a single-crystal (001) surface of dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT), a representative high-mobility donor material, is demonstrated. Surface X-ray diffraction analysis indicated spontaneous alignment of the nearest-neighbor molecular direction of the C₆₀ crystallites uniquely to the a-axis of the DNTT.

This study investigated the crystallographic plane dependence of the reaction of AlN and AlGaN using heated-pressurized water under saturated vapor pressure. The results show that the reaction strongly depends on the crystallographic orientation plane, with no reaction in the +c-plane, the formation of an AlOOH-altered layer in the −c-plane, and etching in the a- and m-planes. These results suggest that the exfoliation mechanism of AlGaN grown on periodically formed AlN nanopillars on sapphire substrates using heated-pressurized water involves etching of a- and m-plane crystals, demonstrating that the proposed method is highly reproducible and versatile for large-diameter wafer exfoliation.

High-speed growth of thick, high-purity β-Ga₂O₃ homoepitaxial layers on (010) β-Ga₂O₃ substrates by low-pressure hot-wall metalorganic vapor phase epitaxy was investigated using trimethylgallium (TMGa) as the Ga precursor. When the reactor pressure was 2.4–3.4 kPa, the growth temperature was 1000 °C, and a high input VI/III (O/Ga) ratio was used, the growth rate of β-Ga₂O₃ could be increased linearly by increasing the TMGa supply rate. A thick layer was grown at a growth rate of 16.2 μm h⁻¹ without twinning. Incorporated impurities were not detected, irrespective of the growth rate, demonstrating the promising nature of β-Ga₂O₃ growth using TMGa.

NiO_x/β-Ga₂O₃p-n heterojunctions fabricated on $(\mathop{2}\limits^{\unicode{x00305}}01),$$(001),$ and $(010)$β-Ga₂O₃ substrates show distinctly anisotropic electrical properties. All three devices exhibited excellent rectification ≥10⁹, and turn-on voltages >2.0 V. The $(010)$ device showed very different turn-on voltage, specific on-resistance, and reverse recovery time compared with $(\mathop{2}\limits^{\unicode{x00305}}01)$ and $(001)$ devices. Moreover, it is calculated that the interface trap state densities for $(\mathop{2}\limits^{\unicode{x00305}}01),$$(001),$ and $(010)$ plane devices are 4.3 × 10¹⁰, 7.4 × 10¹⁰, and 1.6 × 10¹¹ eV^–1cm^–2, respectively. These differences in the NiO_x/β-Ga₂O₃ heterojunctions are attributed to the different atomic configurations, the density of dangling bonds, and interface trap state densities.

Ring-shaped REBa₂Cu₃O_y melt-textured bulks have been successfully grown by the single-direction melt growth (SDMG) method. Three homogeneous DyBa₂Cu₃O_y ring-bulks were directly grown in this study, which exhibited concentrically cone-shaped trapped field distribution on the surface and a high trapped field of 1.84 T at 77 K inside the ring, the highest ever value among reported ring-shaped bulks to date. Furthermore, superconducting properties such as superconducting transitions and critical current densities are highly uniform throughout the bulk, confirming the effectiveness of the SDMG approach. Our findings represent a significant advancement in the fabrication of high-quality bulks suitable for various magnetic applications.

A multi-beam X-ray optical system using a σ-polarization diffraction geometry is proposed and its potential for high-speed tomography using synchrotron radiation is experimentally evaluated. Projection images of a sample are obtained simultaneously from different directions with X-ray beams generated by diffraction of a white synchrotron radiation beam at silicon single crystals. This makes it possible to record a tomographic dataset without rotation of the sample or X-ray source. Data sets of two samples obtained in a proof-of-principle experiment with an exposure time of 1 ms were successfully reconstructed using an advanced compressed-sensing algorithm.

A proof-of-concept experiment for sub-millisecond temporal and 10 μm order spatial resolution 4D X-ray tomography imaging using a multibeam X-ray imaging system is reported. The 3D structure of a tungsten wire during mechanical deformation was reconstructed using a super-compressed sensing-based algorithm from 28 projection images acquired simultaneously with a temporal resolution of 0.5 ms. The multibeam imaging system does not require rotation of the sample, X-ray source or detector. The experiment demonstrates the potential for improving the time resolution in observing non-repeatable dynamic phenomena, such as those occurring in fluids, living beings, or material fractures.

We developed a two-coupled resonant-tunneling-diode (RTD) terahertz (THz) oscillator with a high output power to fill the THz gap. We arranged two RTD mesas in a low-loss air-bridged transmission line for strong mutual coupling and generation of a unique operation mode and integrated a planar ring-slot antenna for efficient THz radiation while satisfying the impedance matching condition. The device structure was fabricated using a multilayer resist process and a carefully controlled wet etching process. The fabricated device exhibited coherent operation and a high output power of approximately 0.24 mW at a high frequency of 925 GHz.

The bio-memristor based on biomaterial has ushered in enthusiasm and optimism in brain-inspired computing systems. Here, the bio-memristor based on sericin has been fabricated with the structure of Ag/sericin/W. The sericin-based bio-memristors demonstrated threshold-switching behavior with low set voltage (∼0.25 V), good cycle-to-cycle uniformity (∼400 cycles), and a large switching window (>100). Interestingly, the device conductance was tuned gradually by the modulation of voltage pulses (amplitude, number, and frequency). The synaptic behaviors can be mimicked, i.e., short-term plasticity, spike-rate-dependent plasticity, and spike-timing-dependent plasticity. This work may open new avenues of bio-memristors in brain-inspired neuromorphic systems.

We demonstrate high-performance normally-off multi-fin β-Ga₂O₃ vertical transistors with a wide fin width from 1.0 to 2.0 μm by using a nitrogen-doped β-Ga₂O₃ high-resistive layer grown by halide vapor phase epitaxy. Normally-off operation was achieved with a threshold voltage of ≥1.3 V, a specific on-resistance of 2.9 mΩ·cm² and a current density of 760 A cm⁻² at a gate voltage of +10 V. The estimated MOS channel field effect mobility was ∼100 cm² V⁻¹ s⁻¹. These findings offer important insights on the development of Ga₂O₃ MOSFETs and show the great promise of Ga₂O₃ vertical power devices.

Sub-femtogram resolution of an in-liquid cavity optomechanical mass sensor based on the twin-microbottle glass resonator is demonstrated. An evaluation of the frequency stability using an optomechanical phase-locked loop reveals that this cavity optomechanical sensor has the highest mass resolution of $(7.0\pm 2.0)\times {10}^{-16}\,{\rm{g}}$ in water, which is four orders of magnitude better than that in our first-generation setup [Sci. Adv. 8, eabq2502 (2022)]. This highly sensitive mass sensor provides a free-access optomechanical probe in liquid and could thus be extended to a wide variety of in situ chemical and biological metrology applications.

We deposited an ultrathin CoFeB(1.1 nm) layer, which functions as a storage layer of MgO-based magnetic tunnel junctions for spin-transfer-torque (STT) magnetoresistive random-access memory (MRAM), on ϕ300 mm wafers at 100 K and investigated its effect on the magnetization dynamics of CoFeB. We observed clear reductions in both the inhomogeneous linewidth and total magnetic damping parameter for the CoFeB layer deposited at 100 K compared to those deposited at 300 K through the improvement in the interfacial quality. The results show that deposition at cryogenic temperatures is an effective manufacturing process for high-quality magnetic thin films with low magnetic damping.

Bipolar degradation in SiC bipolar devices, in which stacking faults (SFs) expand to accommodate the movement of partial dislocations during forward bias application, is one of the critical problems impeding the widespread implementation of SiC power devices. Here we clearly demonstrate that the movement of partial dislocations can be suppressed by proton implantation, which has good compatibility with semiconductor processing, through investigation of the contraction behavior of SFs in SiC epitaxial layers subjected to proton implantation.

Accelerating reverse intersystem crossing (RISC) without sacrificing fast radiative decay is effective in suppressing efficiency roll-off (eRO) in thermally activated delayed fluorescence (TADF)-based organic light-emitting diodes. We here report a TADF emitter, CC-TXO-I, combining a bicarbazole donor (CC) and a sulfur-containing acceptor (TXO). The CC is used to accelerate radiative decay via moderate donor-acceptor torsion angle, and the TXO is expected to provide fast RISC by the heavy-atom effect. We realized very large rate constants of RISC (k_RISCs) of ∼10⁷ s⁻¹. Both k_RISCs and rate constants of radiative decay of CC-TXO-I increased with increasing doping concentration, resulting in improved eROs.

A compact localized surface plasmon resonance (LSPR) sensor system integrated with a filter-free wavelength sensor (FFS) for quantitative virus detection methods was demonstrated. The changed transmission spectrum of the LSPR sensor by molecule was measured using an FFS as a transducer without a conventional spectrometer. We designed and fabricated gold nanostructures optimized for virus detection. As the concentration of S-protein RBD changed from 0.1 to 10 ng ml⁻¹, the change in the current ratio from 0.012 to 0.094 was obtained by the FFS. We expect a compact and rapid virus detection system with qualitatively diagnose to be realized using the proposed method.

Electrochemical reactions with insertions of ions in solids depend on crystallographic orientations. We investigated electrochemical responses of (100), (110) and (111)-oriented oxygen-deficient perovskite SrFeO_2.5+y epitaxial films in electric-field-effect transistor structures with the proton-conducting electrolyte Nafion as a gate insulator. We found that only (100)-oriented SrFeO_2.5+y films exhibit changes associated with gate-voltage-induced electrochemical reductions. Furthermore, elastic recoil detection analysis shows that electrochemically reduced (100) films can accommodate protons, forming the proton-containing oxide H_0.11SrFeO_2.5+y. Our results show that oxygen vacancies form preferentially along the {100} axes and ion diffusion in electrochemical reactions occurs dominantly along the {100} directions in SrFeO_2.5+y.

We propose a method for obtaining crack-free fully-strained SiGe layers on Ge(111). To achieve the crack-free strained SiGe layers, we introduce a patterned area with a sufficient depth (step height) of more than 1 μm on Ge(111) substrates. Because of the complete suppression of the crack propagation from the SiGe layer grown on the outside of the patterned area on Ge(111), we achieve crack-free fully strained SiGe layers on the inside of the patterned area. This approach will drastically expand the applicability of the strained SiGe to the fields of Si photonics and spintronics.

Metasurfaces have attracted widespread interest owing to their ability to control light at the nanoscale level. However, the optical response of dipole mode-based metasurfaces is sensitive to changes in the resonator period and the light incidence angle; thus, the device performance typically degrades in practical applications owing to the presence of non-normal incident light. Here, we study cross-shaped Mie resonators based on quadrupole modes, whose optical response is almost independent of the variations in period and incidence angle. Based on this property of quadrupole modes, we propose a Huygens' metasurface with stable transmissivity at different incident angles.

Strained-Si technology is crucial to improving the performance of metal-oxide-semiconductor field-effect transistors (MOSFETs). To introduce large strain into the channel, we proposed a structure for the negative thermal expansion gate electrode. In this study, we used manganese nitride as the gate material, which is a negative thermal expansion material. The fabricated MOSFETs with the manganese nitride gate showed a 10% increase in electron mobility compared to the MOSFET with the Al gate. The results show that the negative thermal expansion gate technology is promising as a technology booster for MOSFET scaling.

With the peculiar collective transport behaviors and potential applications in thermal management, phonon hydrodynamics at elevated temperatures draws increasing attention in host materials, such as graphite. We map the strength of steady-state phonon hydrodynamic flow in ¹²C purified graphite micro-structures with finite length and width in a broad range of sizes and temperatures. Our theoretical modeling demonstrates that hydrodynamic phonon conduction is largely strengthened and shifts to lower temperature ranges with increasing width from a few micro-meters to 10 μm. The present work provides an insight into phonon hydrodynamics in finite-sized graphitic materials and guides its experimental observation.

In the dry etching process using fluorocarbon (FC) gas, deposited amorphous-CF_x (a-CF_x) films in patterns, such as holes and trenches, strongly affect the etching performance. The influence of the FC gas molecular structures and their atomic compositions on the formation of a-CF_x films at different positions in the holes were investigated. It was found that the deposition region and thickness of the a-CF_x film strongly depend on the molecular structures of the FC gas, such as double bonds, benzene rings, and the atomic ratio of fluorine to carbon.

We report a proof-of-concept demonstration of the anomalous Nernst thermopile driven by solar heating and radiative cooling. The anomalous Nernst thermopile proposed here consists of a zigzag-shaped single magnetic material without any junction structures and black ink-coated alternately on the wires arranged in the zigzag configuration. The voltage generated from this structure increases by an order of magnitude compared to an uncoated structure under the condition with solar heating and radiative cooling, which can further be enhanced by increasing the number of wires. This device concept paves the way for outdoor thermoelectric applications based on the anomalous Nernst effect.

The growth of AlGaN layers on GaN and AlN templates by hydride vapor phase epitaxy (HVPE) was experimentally investigated in detail. Linear control of the Al solid fraction with respect to that of the gas phase was established under conditions with a relatively low H₂ partial pressure. Severe surface deterioration caused by microcrystal inclusion and hillock formation were effectively removed through the use of HVPE conditions that enhanced an etching effect and suppressed parasitic reactions. As a result, AlGaN layers with good surface and crystal qualities were successfully prepared within almost the entire Al-fraction range by the HVPE method.

We measured the thermophysical properties of molten gallium oxide (Ga₂O₃) in a contamination-free and microgravity environment by using the electrostatic levitation furnace in the International Space Station. The density of molten Ga₂O₃ was obtained over a wide temperature range of 2001–2174 K including the undercooled state and found to be expressed as 5004.8–0.4478(T − T_m) (kg m⁻³), where T_m, the melting point, is 2066 K. Measurements of its viscosity and surface tension were also performed by using the drop oscillation method and these values were found to be 337.0 (10⁻³ N m⁻¹) and 13.6 (10⁻³ Pa·s) at 2228 K, respectively.

We researched the mechanical unfolding of protein domains in monomeric protein NuG2 and the tandem polyproteins (NuG2)₈ and (NuG2)₁₆ using a dual-trap optical tweezers system. By stretching NuG2 and its polyproteins, (NuG2)₈ and (NuG2)₁₆ at the constant pulling speed of 500 nm s⁻¹, we achieved the mechanical unfolding force of each domain in these proteins. Besides, we calculated the energy dissipation of NuG2, (NuG2)₈ and (NuG2)₁₆ by measuring the area enclosed by stretching and relaxation traces. Our results represent a key step towards engineering artificial polyproteins with controllable mechanical force and energy dissipation properties for force-buffering and energy dissipator applications.

The effects of a process that minimizes oxidation of SiC on the channel mobility of heavily doped 4H-SiC (0001), (110) and (100) metal-oxide-semiconductor field-effect transistors (MOSFETs) were investigated. High field-effect mobilities were obtained for these MOSFETs even when the acceptor concentration of the p-body (N_A) exceeded 1 × 10¹⁸ cm⁻³. The field-effect mobility for the (0001) MOSFETs reached 25 cm² V⁻¹ s⁻¹ (N_A = 1 × 10¹⁸ cm⁻³). The fabricated (11$\bar{2}$0) and (1$\bar{1}$00) MOSFETs showed very high channel mobilities of 125 cm² V⁻¹ s⁻¹ (N_A = 1 × 10¹⁸ cm⁻³) and 80 cm² V⁻¹ s⁻¹ (N_A = 5 × 10¹⁸ cm⁻³), respectively.

This study proposes an optical rectenna that combines a hollow resonator with a metal–insulator–metal (MIM) tunnel diode that is capable of photoelectric conversion (at various visible and infrared wavelengths). It enables the conversion of thermal radiation with different peak wavelengths, such as sunlight and thermal radiation (from heat sources in various temperature ranges), into electric power. The MIM tunnel diode was placed on the wall of a hollow resonator. It rectified the induced current generated by the resonance of the magnetic field. The photoelectric conversion capability of the proposed device applied to visible light is experimentally demonstrated in this study.

Regarding deep-ultraviolet optical device applications, face-to-face annealed sputter-deposited AlN (FFA Sp-AlN) is a promising alternative to the conventional metalorganic vapor phase epitaxy (MOVPE)-prepared AlN templates on sapphire substrates. However, FFA Sp-AlN tends to exhibit AlGaN growth-related hillock generation and surface morphology deterioration. In this study, we optimized the sputter-deposition conditions for AlN and MOVPE growth conditions for AlGaN to respectively reduce hillock density and size. After confirming AlGaN surface-flattening, we fabricated 263 nm wavelength UV-C LEDs on the FFA Sp-AlN and achieved maximum external quantum efficiencies of approximately 4.9% and 8.0% without and with silicone encapsulation, respectively.

This study presents vertical Ga₂O₃ Schottky barrier diodes (SBDs) with a staircase field plate on a deep trench filled with SiO₂. It was clarified from device simulation that at high reverse voltage operation, the staircase field plate and the deep trench can effectively alleviate electric field concentration in the Ga₂O₃ drift layer and the SiO₂ layer, respectively. The Ga₂O₃ SBDs successfully demonstrated superior device characteristics typified by an on-resistance of 7.6 mΩ cm² and an off-state breakdown voltage of 1.66 kV. These results offer the availability of the trench staircase field plate as an edge termination structure for the development of Ga₂O₃ SBDs.

A magnetic refrigerator that makes use of the magneto-caloric effect realizes a highly efficient cooling device. Since the cooling power of magnetic refrigerators depends largely on the strength of the magnetic field, the use of a superconducting magnet is essential. Using magnetic refrigeration, achieving a liquefaction efficiency of larger than 50% is theoretically possible, which is twice that of conventional gas expansion refrigerators. In this study, an active magnetic regenerative refrigerator, one of the magnetic refrigerators using a superconducting solenoid, was built and hydrogen liquefaction was successfully demonstrated.

We demonstrated continuous-wave lasing of an AlGaN-based ultraviolet laser diode, fabricated on a single-crystal AlN substrate when operating at 5 °C. The threshold current density and device series resistance were reduced by improvements to the epitaxial structure and electrode arrangement. A peak wavelength of 274.8 nm was observed for lasing at a drive current over 110 mA, which corresponded to a threshold current density of 3.7 kA cm⁻². The operating voltage at the threshold current was as low as 9.6 V.

A development of a biocompatible, optical stimulation device capable of adhering to the brain surface and activating spatially separated brain regions is necessary for in vivo optogenetic applications. In this study, a hollow structure for isolating the microLED epitaxial layer was fabricated using the anisotropic KOH wet-etching method. Using a thermal release sheet, a method to transfer microLEDs onto a biocompatible parylene film was established without rotation or misalignment of the microLEDs while retaining their characteristics. Accordingly, a flexible microLED array film was fabricated, which adhered to the surface of the brain of a mouse and exhibited blue emission.

We demonstrate a quantum cascade detector with two coupled double-well structures exhibiting a high peak responsivity of 166 mA W⁻¹ for 8.2 μm detection at 80 K. The coupled double-absorption-well design offers enhanced absorption efficiency. Meanwhile, incorporating another coupled double-well structure in the extractor increases the extraction efficiency. Both factors contribute to the high performance of our device.

We report on an experimental investigation of the jitter of electrons from laser wakefield acceleration. The relative arrival timings of the generated electron bunches were detected via electro-optic spatial decoding on the coherent transition radiation emitted when the electrons pass through a 100 μm thick stainless steel foil. The standard deviation of electron timing was measured to be 7 fs at a position outside the plasma. Preliminary analysis suggested that the electron bunches might have durations of a few tens of femtoseconds. This research demonstrated the potential of laser wakefield acceleration for femtosecond pump–probe studies.

In this study, the monolithic integration of LEDs with different emission colors (wavelengths of 543, 573, and 597 nm) with the directional radiation profiles was demonstrated. InGaN/GaN nanocolumn arrays ordered in a triangular lattice were prepared side by side, changing the diameter of the n-GaN nanocolumn (D_n-GaN). The periodic arrangement of the nanocolumns led to the photonic crystal (PC) effect. The photonic band edge wavelength (λ_B) and the InGaN bandgap were controlled by the D_n-GaN. By controlling λ_B closely at the bandgap wavelength, the PC effect provided directional beam radiation from the LEDs with radiation angles of approximately ±30°.

We developed a novel terahertz-wave detector fabricated on a SiC platform implementing an InP/InGaAs Fermi-level managed barrier (FMB) diode. The FMB diode epi-layers were transferred on a SiC substrate, and a waveguide coupler and filters were monolithically integrated with an FMB diode. Then, the fabricated detector chip was assembled in a fundamental mixer module with a WR-3 rectangular-waveguide-input port. It exhibited a minimum noise equivalent power as low as 3 × 10^–19 W Hz⁻¹ at around 300 GHz for a local oscillator power of only 30 μW.

Developing semiconducting solution-processed ultra-wide bandgap amorphous oxide semiconductor is an emerging area of research interest. However, obtaining electrical conduction on it is quite challenging. Here, we demonstrate the insulator-to-semiconductor conversion of solution-processed a-Ga₂O_x (E_g ∼ 4.8 eV) through hydrogen annealing. The successful conversion was reflected by the switching thin-film transistor with saturation mobility of 10⁻² cm² V⁻¹s⁻¹. We showed that H incorporated after hydrogen annealing acts as a shallow donor which increased the carrier concentration and shifted the Fermi level (E_F) closer to the conduction band minimum.

In large biomolecular systems such as protein complexes, there are huge numbers of combinations of inter-residue interactions whose comprehensive analyses are often beyond the intuitive processing by researchers. Here we propose a computational method to allow for a systematic analysis of these interactions based on the fragment molecular orbital calculations, in which the inter-fragment interaction energies are comprehensively processed by the singular value decomposition. For a trimer complex of SARS-CoV-2 spike protein, three-body interactions among residues belonging to three chains are analyzed to elicit a small number of essential interaction modes or networks crucial for the structural stability of the complex.

We fabricated high forward and low leakage current trench MOS-type Schottky barrier diodes (MOSSBDs) in combination with a field plate on a 12 μm thick epitaxial layer grown by halide vapor phase epitaxy on β-Ga₂O₃ (001) substrate. The MOSSBDs, measuring 1.7 × 1.7 mm², exhibited a forward current of 2 A (70 A cm⁻²) at 2 V forward voltage and a leakage current of 5.7 × 10^–10 A at −1.2 kV reverse voltage (on/off current ratio of > 10⁹) with an ideality factor of 1.05 and wafer-level specific on-resistance of 17.1 mΩ · cm².