This work acquires a vertical β-Ga₂O₃ Schottky barrier diode (SBD) with the advanced termination structure of p-type NiO_x and n-type β-Ga₂O₃ heterojunctions and coupled field plate structures to alleviate the crowding electric field. A Ga₂O₃ SBD delivers an average breakdown voltage of 1860 V and a specific on-resistance of 3.12 mΩ cm², yielding a state-of-the-art direct-current Baliga's power figure of merit of 1.11 GW/cm² at an anode area of 2.83 × 10⁻⁵ cm². In addition, the Ga₂O₃ SBD with the same fabrication process at a large area of 1.21 × 10⁻² cm² also presents a high forward current of 7.13 A, a breakdown voltage of 1260 V, and a power figure-of-merit of 235 MW/cm². According to dynamic pulse switching and capacitance-frequency characteristics, an optimized p-NiO_x/Ga₂O₃ interface with a maximum trap density of 4.13 × 10¹⁰ eV⁻¹ cm⁻² is delivered. Moreover, based on the forward current-voltage measurement at various temperatures, the physics behind a forward conduction mechanism is illustrated. Ga₂O₃ SBDs with p-NiO_x/n-Ga₂O₃ heterojunction termination, field plate, high power figure of merit, and high quality interface as well as suppressed resistance increase after dynamic pulse switching, verifying their great promise for future high power applications.

In this Letter, we report on establishing high performance hysteresis-free and μs-switching depletion/enhancement-mode (D/E-mode) β-Ga₂O₃ heterojunction (HJ) field effect transistors (FETs) with the state-of-art power figure-of-merit (P-FOM). By optimizing the p-NiO_x/n-Ga₂O₃ interface and n-Ga₂O₃ recess technology, a positive threshold voltage (V_T) as well as a low subthreshold slope can be substantially achieved. The trade-off between the on-resistance (R_on,sp) and breakdown voltage (BV) is improved by incorporation of T-shaped NiO_x, resulting in the R_on,sp of 6.24/13.75 mΩ cm² and the breakdown voltage (BV) of 2145/1977 V for D/E-mode devices and yielding the P-FOM = BV²/R_on,sp to be 0.74/0.28 GW/cm². To the best of all the authors' knowledge, those P-FOMs are the highest ones among all published lateral Ga₂O₃ FETs. Benefited from the high-quality interface, a negligible hysteresis of 4 mV and μs-switching can be essentially achieved, showing the great promise of Ga₂O₃ HJ-FETs for future high-power, high-efficiency, and high-speed power electronics.

The effect of neutron irradiation on the electrical performance of the $\beta $ -Ga2O3 Schottky barrier diode (SBD) device has been studied in this work. After equivalent 1 MeV neutron irradiation with a fluence of $1\times 10^{{14}}$ n/cm2, a 20% decrease in the forward current density ( ${J}_{\text {F}}{)}$ , a 75% reduction in the reverse current density ( ${J}_{\text {R}}{)}$ , and a 300 V increase in the breakdown voltage ( ${V}_{\text {br}}{)}$ have been observed according to current–voltage ( ${I}$ – ${V}{)}$ measurements. Utilizing the frequency-dependent conductance technique, it is found that the density of interface states located at Pt/Ga2O3 increases slightly from $2.6\times 10^{{12}}$ – $6.4\times 10^{{12}}$ to $2.9\times 10^{{12}}$ – $7.0\times 10^{{12}}$ cm $^{-{2}}$ eV $^{-{1}}$ with an increase in trap activation energy from 0.09–0.122 to 0.096–0.134 eV after neutron irradiation. Furthermore, based on the capacitance–voltage ( ${C}$ – ${V}{)}$ measurement, it is observed that the carrier concentration across the Ga2O3 drift layer was decreased from $1.80\times 10^{{16}}$ to $1.35\times 10^{{16}}$ cm $^{-{3}}$ after neutron irradiation. Considering the device performance change, it indicates that the bulk traps within the Ga2O3 drift layer instead of interface states dominate the device degradation.

In recent decades, gallium nitride (GaN) high-electron-mobility transistor (HEMT) has become increasingly popular for microwave applications due to its wide bandgap and high saturated electron velocity. However, self-heating inhibits the improvement of its electrical characteristics and reduces device reliability. In this study, a thermoelectric analysis based on embedded microfluidic cooling is performed. By embedding the microchannel into the silicon carbide (SiC) substrate, the coolant can be introduced directly to realize active near junction cooling. According to the thermal resistance model, embedded cooling shortens the thermal path and enhances the capacity of heat convection, and the improvement in the HEMT output characteristics is also verified experimentally. The saturation current increases by 19.5%, and the heat flux of the gates reaches 6349.2 W/mm2 at 70 mL/min, which is 1172% higher than that of traditional remote cooling. The maximum temperature is only 67.4 °C. Therefore, the embedded microfluidic cooling scheme can markedly suppress the self-heating effect and further explore the electrical potential of GaN-based devices.

Defect behaviors in the degradation of AlGaN-based UV-C light emitting diodes (LEDs) under constant current stress have been intensively investigated in this work. It is found that both the reduction of the optical power and the increase in the leakage current are derived from the newly generated Ga vacancy (V_Ga) along dislocation, based on the evidence of a strong “yellow” emission peak at 515 nm in the photoluminescence spectra and an energy level of 0.25–0.38 eV. More importantly, the defect evolution behind it was determined through the deep level transient spectroscopy, secondary ion mass spectrometry measurements, and density functional theory. V_Ga is found to be generated by the departure of the unintentionally doped Mg from Mg_Ga along dislocation in the Si-doped region. The high activity of the unintentionally doped Mg under electrical stress can be an essential factor in the degradation of UV-C LEDs. This study not only provides an in-depth insight into the electrical stress-induced degradation in UV-C LEDs but also sheds light on the way for fabricating AlGaN-based devices with high reliability.

In this work, the single-event burnout (SEB) mechanism of p-GaN gate AlGaN/GaN HEMTs has been studied systematically. The irradiation experiment was carried out based on Ta ions with high linear energy transfer of 75.4 MeV/(mg/cm2), a standard criterion for commercial space applications. It is clearly observed that both the drain current and gate current increase during the irradiation. With the increasing drain bias, the device burns out eventually. Technology computer-aided design simulation was used to explore the possible burnout mechanism. The local high electric field peak induced by the electron and hole redistribution was proposed to explain the permanent damage. When heavy ions impact the device, electron–hole pairs are formed. With the aid of a horizontal electric field across the channel, electrons and holes move toward the drain and gate, respectively. The accumulation of electrons and holes around the drain edge and gate edge induces the local high electric field, which is even higher than the intrinsic breakdown electric field of GaN and AlGaN. The scanning electron microscope results verified the proposed SEB mechanism. This research offers significant theoretical and experimental insights for evaluating the reliability of GaN power devices against high-energy single-event burnout in aerospace applications.