Ga2O3 is an ultrawide-band-gap semiconductor, which performs good application prospect in the power devices and solar-blind photodetectors. MgO (100) is usually acted as the heteroepitaxial substrate because of the rather low lattice mismatch with Ga2O3 films. However, conventional film deposition methods typically require high growth temperatures. In this paper, high-quality Ga2O3 films are prepared on MgO (100) substrate through atomic layer deposition (ALD) method at the low temperature of 350 degrees C. The films exhibit a preferred (100) orientation, which are achieved through a temperature-induced phase transition from the metastable y-phase to the stable (3-phase. The structural characteristics of the (3-Ga2O3 films using PE-O2 or O3 as oxygen source are similar with each other, which present small full width at half maxima (FWHM) of 0.060 degrees for the (600) plane rocking curve and low surface roughness of only 0.187 nm at 350 degrees C. After annealing at 700 degrees C, the crystalline quality and surface morphology of the (3-Ga2O3 films on MgO substrate are both further improved slightly. Two types of atomic configurations are also constructed to simulate the lattice matching of epitaxial (3-Ga2O3 films on MgO (100) substrate. The results are beneficial for the applications of Ga2O3-based electronic and photoelectron devices on MgO substrates especially at the low-temperature condition.

This paper presents a novel work function modulated Fin-channel schottky barrier diode (WFM-Fin-SBD) with optimized electrical characteristics. The architecture incorporates Ti as the Schottky metal on the Fin top surface to reduce the turn-on voltage (Von) and mitigate forward conduction loss. Simultaneously, Ni is selectively deposited on the Fin sidewalls and trenches bottom. This configuration ensures effective carrier depletion within the fin channel under both zero-bias and reverse-bias conditions, thereby suppressing reverse leakage current and enhancing the breakdown voltage. As a result, the WFM-Fin-SBD achieves superior performance metrics, including a lowVonof 0.35 V, a specific on-resistance (Ron,sp) of 6.25 mΩ·cm2, and a current density of 598 A cm-2at 6 V. Under reverse bias, the enhanced depletion effect at the Ni/Ga2O3interface effectively pinches off the conductive channel, which suppresses the leakage current and enables a breakdown voltage of -241 V, which is approximately 5.5 times that of conventional Ti-SBDs. Furthermore, frequency-dependent conductance measurements reveal that the interface trap density (Dit) of the WFM-Fin-SBD is situated between those of the Ti-SBD and the Ni-SBD. The slightly elevatedDitcompared to the Ni-SBD is mainly attributed to the presence of Ti at the Fin top. Meanwhile, TCAD simulations elucidate the underlying physical mechanisms. The proposed WFM-Fin-SBD demonstrates superior performance, positioning it as a promising candidate for high-efficiency power electronics.

Lithium niobate photonic crystal nanobeam cavity (PCNBC) represents a premier platform for integrated electro-optics, offering deep sub-wavelength mode confinement, enhanced light-matter interactions, and ultralow power consumption. However, accurate characterization of the electro-optic (EO) tuning efficiency in such high-Q devices is fundamentally impeded by DC drift, a time-dependent spectral instability arising from charge redistribution, surface screening, or buffer layer relaxation under sustained electric fields. Here, we report the systematic analysis of DC drift dynamics in lithium niobate nanocavities and demonstrate that conventional quasi-static DC voltage scanning yields highly unreliable characterization data. To circumvent this limitation, we introduce a drift-free, dynamic measurement methodology that employs high-frequency triangular-wave voltage sweeps to effectively decouple the instantaneous electronic Pockels response from slow charge-relaxation processes. Validated across 35 devices with varying electrode geometries, our method delivers reproducible tuning efficiency of 4.3-4.5 pm/V with a low coefficient of variation of 1.1

This paper presents a novel work function modulated Fin-channel schottky barrier diode (WFM-Fin-SBD) with optimized electrical characteristics. The architecture incorporates Ti as the Schottky metal on the Fin top surface to reduce the turn-on voltage (Von) and mitigate forward conduction loss. Simultaneously, Ni is selectively deposited on the Fin sidewalls and trenches bottom. This configuration ensures effective carrier depletion within the fin channel under both zero-bias and reverse-bias conditions, thereby suppressing reverse leakage current and enhancing the breakdown voltage. As a result, the WFM-Fin-SBD achieves superior performance metrics, including a low Von of 0.35 V, a specific on-resistance (Ron,sp) of 6.25 m Omega & centerdot;cm2, and a current density of 598 A cm-2 at 6 V. Under reverse bias, the enhanced depletion effect at the Ni/Ga2O3 interface effectively pinches off the conductive channel, which suppresses the leakage current and enables a breakdown voltage of -241 V, which is approximately 5.5 times that of conventional Ti-SBDs. Furthermore, frequency-dependent conductance measurements reveal that the interface trap density (Dit) of the WFM-Fin-SBD is situated between those of the Ti-SBD and the Ni-SBD. The slightly elevated Dit compared to the Ni-SBD is mainly attributed to the presence of Ti at the Fin top. Meanwhile, TCAD simulations elucidate the underlying physical mechanisms. The proposed WFM-Fin-SBD demonstrates superior performance, positioning it as a promising candidate for high-efficiency power electronics.

In this article, an enhancement-mode (E-mode) beta-Ga2O3 Schottky-heterojunction composite field-effect transistor (SHJC-FET) was reported. By employing a Schottky-NiOX heterojunction composite structure, which combines the strengths of Schottky junction and NiOX p-n heterojunction gates, state-of-the-art performance has been achieved, including a high power figure of merit (PFOM) of 0.80 GW/cm(2). This E-mode transistor delivers impressive characteristics, with a maximum drain-to-source current (ID) of 189.5 mA/mm, a breakdown voltage (BV) of 2230 V, and a specific ON-resistance (R-ON, SP) of 6.21 m Omega.cm(2). We also explore and compare the design and performance of two additional devices: a conventional heterojunction field-effect transistor (CHJ-FET) and a self-aligned heterojunction fieldeffect transistor (SAHJ-FET). The physical mechanisms underlying the operation of all three structures are analyzed and summarized in detail. Furthermore, the SHJC-FET demonstrated remarkable resilience under stress testing. Under gate stress conditions, the gate current increased by less than one order of magnitude over a period of 1200 s. Similarly, during OFF-state step drain stress, the drain current rose by only 51%. These findings highlight that the SHJC-FET could offer superior transport characteristics.

beta-Ga2O3 FinFETs are promising for high-power electronic applications owing to their ultra-wide bandgap and high breakdown field. To overcome the inherently limited current capability of single-fin devices, multi-fin architectures were introduced to enhance the total on-state current. However, transfer characteristics reveal that when the fin number is increased by a factor of 16, the saturation current at V-D = 10 V rises only from 0.112 to 1.22 mA-significantly below the expected linear scaling-and premature current degradation emerges at high V-G. Such deviation indicates pronounced self-heating and electro-thermal coupling within densely packed fin arrays. Furthermore, under high-power operation, evident nonlinearities appear in both temperature rise and current response, further supporting the thermally driven origin of performance degradation. Raman thermography under identical per-fin current conditions reveals a much higher peak temperature (70.77 degrees C) in the multi-fin device compared to the single-fin counterpart (28.8 degrees C), confirming severe thermal crosstalk. These findings elucidate the thermal origin of the non-ideal current scalability and provide essential insights for thermally aware three-dimensional design of beta-Ga2O3 FinFETs.

In this article, a beta-gallium oxide (beta-Ga2O3)-based enhancement-mode (E-mode) FinFET is proposed, in which the combination of the Fin channels and recessed gate enables synergistic regulation of the threshold voltage and gate breakdown voltage. The device exhibits a threshold voltage(VTH) of + 0.4 V, a gate overdrive voltage up to 14.6 V, and a current density of 243 mA/mm. By employing heavily doped source/drain regions, an ohmic contact resistance as low as 0.76 Omega & sdot; mm and a specific on-resistance (Ron,sp) of 1.73 m Omega & sdot; cm(2) are achieved. Furthermore, comprehensive small-signal RF measurements are performed, based on which an accurate equivalent circuit model is established through systematic fitting and parameter extraction. The extracted intrinsic and parasitic parameters enable quantitative analysis of the factors limiting the high-frequency performance, yielding fT/fMAX values of 1.5-3.5 GHz for the beta-Ga2O3-based E-mode FinFET.

This study elucidates the physical mechanisms governing growth mode transitions in (100) β-Ga2O3 MOCVD homoepitaxy when replacing Ar with N2 carrier gas. Ar promotes step-flow growth with RMS roughness of 0.209 nm and no twin defects. N2 triggers 2D island nucleation, generating extensive twin boundaries and increasing roughness to 1.545 nm. Integrating boundary-layer mass-transfer kinetics with BCF theory, we find that the higher kinematic viscosity of N2 forms a thicker boundary layer, impeding Ga precursor transport. This elevates the effective surface VI/III ratio, creating an oxygen-rich environment that increases the adatom migration barrier. Consequently, the Ga diffusion length drops below the critical terrace width, forcing the transition to 2D islanding. Guided by this framework, we optimized the N2-driven process by tuning the O2/TMGa molar flow ratio. At an optimal ratio of 300, the suppressed Ga diffusion kinetics are compensated, restoring step-flow growth. These optimized films show complete elimination of twin defects and a recovered RMS roughness of 0.267 nm. This work establishes a mechanistic framework linking carrier-gas properties to boundary-layer transport and surface diffusion kinetics, enabling rational process design for cost-effective scalable growth of device-grade β-Ga2O3 homoepitaxial films.

The beta-Ga2O3 epitaxial thin films were grown on (001) beta-Ga2O3 substrates using metalorganic chemical vapor deposition (MOCVD), and the effects of key growth parameters - including temperature, pressure, and oxygen-to-gallium ratio (O2/Ga) - on the crystalline quality, surface morphology, and electrical properties of the films were systematically investigated. The results show that while variations in these parameters did not alter the (001) preferential orientation of the beta-Ga2O3 films, they significantly influenced other properties. By optimizing the growth parameters, films with a surface roughness as low as 1.5 nm and the full width at half maximum (FWHM) of 33.7 arcsec were achieved. X-ray photoelectron spectroscopy (XPS) analysis showed that the oxygen vacancy concentration was significantly reduced under the optimized O2/Ga ratio of 820. Schottky barrier diodes (SBDs) were fabricated from three different beta-Ga2O3 films grown under distinct O2/Ga ratios. The SBD fabricated under the optimized O2/Ga ratio of 820, exhibits a low turn-on voltage of 0.5 V, low on-resistance of 0.022 m Omega & sdot;cm2, and a high forward current density of 678.16 A/cm2 at 3 V. These results provide essential material and theoretical foundations for the development of beta-Ga2O3 based high-power electronic devices.

Wide bandgap semiconductors have gained significant attention in RF device applications owing to their superior carrier mobility. To enhance the carrier mobility within the channel, researchers have employed the deposition of gate dielectrics to modulate the internal stress of GaN. Nevertheless, this dielectric deposition process inevitably introduces defects, which can detrimentally impact device performance. Our group previously demonstrated that the regulation of ferroelectric polarization effectively mitigates interface states. In this paper, the interplay between GaN internal stress and carrier mobility under the influence of nanochannel ferroelastic stress modulation has been explored. The output current and transconductance exhibited substantial enhancements, reaching 1026 mA/mm and 259 mS/mm, respectively. After the 680 nm channel formation, the compressive stress was reduced to 0.37 GPa, with carrier mobility increasing to 2610 cm2/V & sdot;s (110 % of the initial value). The reduction of compressive stress improves carrier mobility to a certain extent. This research provides a straightforward and efficacious approach to investigating the factors through which ferroelastic modulation influences the internal stress in GaN.

Electro-thermal improvement is critical for β-Ga2O3 power devices to mitigate self-heating while maintaining high-voltage capability. Here, we propose a β-Ga2O3 cage-integrated slanted-fin MOSFET (C-SFMOSFET). By optimizing the cage-to-fin and cage-to-drain distances, the cage sequence simultaneously strengthens channel depletion and enhances heat dissipation in the gate-to-drain region. Compared with the baseline slanted-fin MOSFET (SFMOSFET), the proposed 4-cage C-SFMOSFET achieves a 1.75× higher Baliga’s figure of merit and reduces the peak junction temperature by 8 °C at 0.55 W/mm. These results indicate that the proposed device layout can effectively improve device-level electro-thermal performance and further exploit the inherent advantages of ultra-wide-bandgap β-Ga2O3.

In this study, a typical hillock surface defect was discovered in (010) β-Ga2O3 thin films grown by metal-organic chemical vapor deposition (MOCVD), and the morphology and structure were systematically investigated. The observed defects exhibit a polygonal shape with a ridge-like hillock along the [001] direction. Transmission electron microscopy (TEM) microanalysis reveals that polygonal hillock defects are composed of twin grains forming an inverted pyramid shape embedded in the epitaxial layer, which exhibits twofold rotational symmetry along the [100] crystal direction. The boundary between the defective and perfect lattices appears band-like, characterized by complex faults, with structural relationships between the twin region and the matrix identified as [001]matrix∥[010]Defect and −310matrix∥−201Defect. The origin of surface defects in the (010) β-Ga2O3 homoepitaxial layers could be attributed not only to the extent of substrate defects but also to epitaxial process conditions. The definitive explanation is the localized aggregation of gallium atoms/oxygen vacancies during the growth process, as evidenced by energy-dispersive X-ray (EDX) analysis and optimized experiments. This work provides brand-new perspectives into the study of defects in β-Ga2O3 epitaxial films, which further advances the application of Ga2O3 materials in power device technologies.

A /3-Ga2O3 trench MOS barrier Schottky (TMBS) diode with a novel terminal structure of positive bevel mesa and arc bottom corners has been designed and realized in this work. O2 plasma, hydrogen fluoride (HF), and tetramethylammonium hydroxide (TMAH) are used for post-etching treatment of devices, respectively. Measurement results shows that the specific on-resistance of the three devices are nearly with the same value of 2.60 m Omega & sdot;cm2. The breakdown voltage of the devices with O2 plasma, HF, and TMAH treatments are 1280 V, 1440 V, and 1800 V, respectively. Moreover, it is worth nothing that devices treated with O2 plasma have a lower reverse leakage. In addition, the breakdown location of the device is determined to be at the /3-Ga2O3 interface under the edge of the field plate by combining simulation and capacitance breakdown testing. AFM and XPS are used to analyze the surface properties of /3-Ga2O3 after post-etching treatments. The results show that the TMAH treatments have the most significant effect on reducing surface roughness, and the O2 plasma treatments is the most effective in decreasing oxygen vacancies.

In this article, the threshold voltage ( Vth) characteristic of beta -Gallium Oxide ( beta -Ga2O3) based enhancement mode (E-mode) heterojunction gate field effect transistor (FET) is investigated. A self-aligned gate Ga2O3/NiO x heterojunction FET (SHJ-FET) and a conventional gate Ga2O3/NiOx heterojunction FET (CHJ-FET) are fabricated to research the variation of threshold voltage with the length of NiOx . It is found that the Vth of SHJ-FET and CHJ-FET are about 0.6 and 2.4 V, respectively. Moreover, the power figure of merit (PFOM) values of SHJ-FET and CHJ-FET are 0.37 and 0.35 GW/cm(2), respectively. Due to the larger L-NiOx/L-G ratio, the Vth of CHJ-FET is more positive. Then, a physical threshold voltage model of beta -Ga2O3-based heterojunction gate FETs is built, and the Vth is extracted by varying the geometries of the heterojunction gate. Finally, the correctness of the physical model is verified by fitting the threshold voltage of the actual device with the simulation results. Furthermore, the physics mechanism of the influence of the L-NiOx/L-G , as well as the position of NiOx on the off-state electric field distribution of the device, has also been studied.

In this paper, to overcome the issues of high roughness and defect density in (001) β-Ga2O3 epitaxial films grown by MOCVD, a novel in-situ pulsed Al atom assisted growth method is proposed. Compared to films grown by conventional growth methods, the β-Ga2O3 epitaxial film grown using this method exhibited lower RMS roughness and a smaller FWHM of the (002) peak in the X-ray rocking curve. Additionally, oxygen vacancy defects within the film are significantly reduced, and Al incorporation is relatively limited without inducing lattice distortion. The width of serrations at the substrate-epitaxial layer interface is reduced from 70 nm to 17 nm, demonstrating improved interface flatness. The mechanism of pulsed Al atoms in optimizing homoepitaxial growth of (001) β-Ga2O3 is proposed, including their roles as preferential nucleation sites for Ga atoms, their inhibitory effects on Ga2O formation and desorption, and the enhancement of atomic diffusion while minimizing parasitic side reactions. The phenomenon of epitaxial orientation rotation is observed, and a hypothesis is proposed regarding the causes of the difference in rotation angle and surface flatness. Additionally, Schottky barrier diodes (SBDs) are also fabricated to study the electrical properties of these epitaxial materials. The epitaxial layer obtained through the pulsed Al atom assisted growth method exhibited a breakdown field strength of 1.8 MV/cm. These results demonstrate that the pulsed Al atom assisted growth method may serve as a valuable reference for achieving high-quality (001) β-Ga2O3 epitaxial growth by the MOCVD method.

Integrated all-optical oscillators are essential building blocks for optical computing, communications, and neuromorphic processing. However, current resonator-based designs are limited to low MHz frequencies by slow thermal dynamics and often require high power or electrical biasing. Here, we develop a compact silicon photonic crystal nanobeam cavity (PCNBC) platform that simultaneously manages both optical and thermal dynamics to generate high-frequency self-sustained oscillations. The high quality factor (Q) and small mode volume (Vmode) of this device enhance optothermal nonlinearities, while its nanoscale geometry ensures rapid heat dissipation. Supported by FEM simulations, our experimental results demonstrate oscillation frequencies up to 45 MHz at a low threshold power of 223 μW. Furthermore, we show wide tunability of both frequency and duty cycle through optical control of the input power and wavelength detuning. This fully passive and bias-free platform offers a compelling solution for chip-scale optical clocks, neuromorphic photonic circuits, and low-power signal processing.

In this study, β-Ga2O3 epitaxial thin films were grown on (001) β-Ga2O3 substrates using metalorganic chemical vapor deposition (MOCVD), and the effects of key growth parameters-including temperature, pressure, and oxygen-to-gallium ratio (O2/Ga)-on the crystalline quality, surface morphology, and electrical properties of the films were systematically investigated. The results show that while variations in these parameters did not alter the (001) preferential orientation of the β-Ga2O3 films, they significantly influenced other properties. By optimizing the growth parameters, films with a surface roughness as low as 1.5 nm and a FWHM of 33.7 arcsec were achieved. X-ray photoelectron spectroscopy (XPS) analysis showed that the oxygen vacancy concentration was significantly reduced under the optimized O2/Ga ratio of 820. Schottky barrier diodes (SBDs) were fabricated from three different β-Ga2O3 films grown under distinct O2/Ga ratios. The SBD fabricated under the optimized O2/Ga ratio of 820, exhibiting a low turn-on voltage of 0.5 V, low on-resistance of 0.022 mΩ·cm2, and a high forward current density of 678.16 A/cm2 at 3 V. These results provide essential material and theoretical foundations for the development of β-Ga2O3 based high-power electronic devices.

This letter reports the fabrication and characterization of beta-Ga2O3 metal/ferroelectric/insulator/semiconductor (MFIS) capacitors employing 3 types of HfO2-ZrO2 superlattice (SL) ferroelectric gate dielectrics: SL5, SL10, and SL15, constructed by alternating 5,10, and 15 ALD cycles of HfO2 and ZrO2, respectively, with conventional Hf0.5Zr0.5O2 (HZO) as a reference. Following rapid thermal annealing (RTA) at 550 degrees C for 30 s, all dielectrics are confirmed to exhibit the orthorhombic (111) phase by grazing-incidence x-ray diffraction (GIXRD). Electrical measurements reveal that the SL5 structure achieves an outstanding reduction in leakage current, decreasing from 0.936 A cm(-2) (HZO) to 0.004 A cm(-2) at 3 V, and exhibits the highest remanent polarization (2P(r) = 29.3 mu C cm(-2)), compared to 27.3 mu C cm(-2) (HZO), 22.4 mu C cm(-2) (SL10), and 17 mu C cm(-2) (SL15). Moreover, the SL5 capacitor demonstrates excellent reliability, maintaining robust endurance up to 1 x 10(11) cycles at room temperature and 1 x 10(10) cycles at 150 degrees C without degradation and stable retention over 1 x 10(4) s. Importantly, interface state analysis reveals that after annealing, SL5 maintains the lowest and most stable interface trap density within the energy range of 0.25-0.45 eV. The trap state density (6.39 x 10(12)-7.11 x 10(12) cm(-2) eV(-1)) is significantly lower than that of HZO in the same energy range. These results highlight the advantages of superlattice-engineered ferroelectric gate dielectrics for achieving high-quality interfaces, low leakage current, and stable ferroelectric performance, providing a promising route toward high-performance, enhancement-mode beta-Ga2O3 MOSFET devices for next-generation power electronics.

In this letter, by implementing thermal oxidation (TO) technology, vertical Ga2O3 Schottky barrier diodes were directly fabricated on a heavily doped single-crystal (001) β-Ga2O3 substrate without epitaxial growth. The electron concentration in near-surface region of the Ga2O3 substrate was greatly reduced by introducing high-temperature TO processing. X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) results indicated that the oxygen vacancy (VO) content in the near-surface region was significantly decreased, while a 500–700 nm acceptor-like defect energy level combining multiple gallium vacancy (VGa) generated, and compensated for, the free carriers after annealing in an oxygen-rich atmosphere at high temperature. The annealing temperature and time were analyzed and optimized. Finally, vertical β-Ga2O3 SBDs with a breakdown voltage (Vbr) of 460 V, specific on-resistance (Ron,sp) of 10.5 mΩ·cm2 and a power figure-of-merit (PFOM) of 20.2 MW/cm2, were demonstrated when the annealing temperature and time were 900 °C and 2 h. These results indicate that vertical β-Ga2O3 SBDs can be directly fabricated on a single-crystal substrate without epitaxial growth, providing a new method of reducing the cost of such devices.