(001) β-Ga₂O₃ homoepitaxy on commercially available large-size (001) β-Ga₂O₃ substrates remains a significant challenge for the wide bandgap semiconductor community. In this Letter, high-quality homoepitaxial (001) β-Ga₂O₃ films were grown via metalorganic chemical vapor deposition (MOCVD) with the assistance of an in situ indium surfactant, where the growth modes and mechanisms were also elucidated. During the growth of β-Ga₂O₃, an etching process occurred by the desorption of the suboxide Ga₂O, resulting in rough surface morphology with streaky grooves oriented along the [010] direction. It is postulated that the parallel grooves were associated with the surface desorption and anisotropic diffusion characteristics of β-Ga₂O₃. To suppress the desorption, indium surfactant was introduced into the growth environment. A 2D-like growth feature was prompted subsequently by the coadsorption of In and Ga atoms, accompanied by relatively smooth surface morphology. The crystal quality had no degradation despite the incorporation of indium in the epitaxial film. The O II peak of the β-Ga₂O₃ film shifted ∼0.5 eV toward higher binding energy due to an increasing number of oxygen vacancies originating from the indium incorporation. This work provides a systemic investigation on the growth of high-quality (001) β-Ga₂O₃ homoepitaxial films by MOCVD, which is critical for the development of β-Ga₂O₃ electronic devices for future power switching and RF applications.

In this article, the normally- OFF etching-free p-GaN stripe array gate AlGaN/GaN high-electron-mobility-transistors (PSAG-HEMTs) are designed and experimentally demonstrated through hydrogen plasma treatment. The unique threshold voltage ( ${V}_{TH}$ ) modulation technique based on the PSAG structure is proposed and simulated. Using this method, the ${V}_{TH}$ can be continuously shifted from −0.14 to +1.03 V by just tuning the widths of p-GaN ( ${W}_{p}$ ) and hydrogenated p-GaN (HR-GaN) stripes. To improve breakdown voltage (BV), the PSAG is extended to the drain side based on the 3-D simulation results so that a new electric-field peak is introduced at the edge of the PSAG in the drain side and then the surface electric field is optimized. Besides this, an enhanced conductivity effect is observed and results in a low ON-resistance. The fabricated PSAG-HEMT with $0.75~\mu \text{m}~{W}_{p}$ and 4- $\mu \text{m}$ extension length ( ${L}_{E}$ ) exhibits a positive ${V}_{TH}$ of +0.8 V, a low specific ON-resistance ( ${R}_{\text {ON,sp}}$ ) of 2.73 $\text{m}\Omega \cdot cm^{2}$ , a high BV of 852 V (1449 V) at ${I}_{D} = 1 ~\mu \text{A}$ /mm, and BFOM of 266 MW/cm ² (769 MW/cm ² ) with substrate grounded (floating), which demonstrate significant improvements over Reference single-gate E-mode and D-mode devices. This work provides a promising architecture for future high voltage normally- OFF p-GaN HEMT devices.

In this work, a dual-band junction field effect phototransistor (JFEPT) was fabricated by integrating p-type BP with Si doped β-Ga ₂ O ₃ . The operation principle of the JFEPT was systematically investigated by commercial TACD software SILVACO. The results indicate that the photocurrent mainly formed by electrons under short wave radiation, while it is composed of electrons and holes under long wave irradiation. In addition, the Ga ₂ O ₃ doping concentration was determined to be 3×10 ¹⁶ cm ^-3 to obtain a large photo-to-dark current ratio ( PDCR ). The threshold voltage ( V _th ) of the fabrication JFEPT was 0.65 V, indicating that the device working in normally-off state. The drain current was ~ 10 ^-6 mA/mm and the on/off ratio is 10 ⁵ at V _G = - 4 V and V _DS = 5 V. And the device exhibits low leakage current of 2.84×10 ^-6 mA/mm. Under 254 nm and 808 nm illumination, the PDCR were 14713.79 and 5.53, and the responsivity were calculated to be 2.39×10 ⁶ mA/W and 535 mA/W, respectively. What’s more, a low noise current of 0.17 nA/Hz ^1/2 at 1 Hz is beneficial for the device to detect the ultra-weak optical signal. This work provides an important reference for the realization of high-performance UV-IR dual-band detector.

This letter demonstrates high-performance lateral p-GaN/AlGaN/GaN hybrid anode diodes (HPT-HADs) using a novel hydrogen plasma treatment. Without field plates (FPs) or passivation, the HPT-HAD with anode-cathode distance ( ${L}_{\text {AC}}$ ) of 20 $\mu \text{m}$ showed reverse breakdown voltage ( BV ) of 2.01 kV with differential specific ON-resistance ( ${R}_{\text {ON,sp}}$ ) of 2.09 $\text{m}\Omega \cdot $ cm ² and power figure-of-merit (FOM) of 1.93 GW/cm ² . Moreover, the device also exhibited excellent rectifying behaviors with an output current density of 598 mA/mm, an ${I}_{\text {ON}}/{I}_{\text {OFF}}$ ratio of $\sim 10^{{10}}$ , an ideality factor ( $\eta$ ) of 1.04, and a turn-on voltage ( ${V}_{\text {T}}$ ) of 1.3 V. The devices also had a negligible hysteresis due to the hydrogenated p-GaN cap layer and the low-damage plasma treatment. The p-GaN/AlGaN/GaN HAD anodes are promising for next-generation high-voltage power electronics.

In this work, a p-GaN/AlGaN/GaN hybrid anode diode (HAD) temperature sensor was fabricated by using hydrogen plasma treatment. The zero-temperature coefficient (ZTC) is about 0.7 V from the ${I}$ – ${V}$ characteristics measured at various temperatures. At the forward region below the ZTC bias point, the anode voltage ( ${V}_{{\mathrm {A}}}$ ) at a specific anode current density ( ${I}_{{\mathrm {A}}}$ ) decreases linearly with the increase of temperature, resulting in a sensitivity ranging from 1.64 mV/K (10 ⁻⁵ mA/mm) to 0.69 mV/K (10 ⁻² mA/mm). The leakage current at the reverse bias also presents a temperature-dependent behavior with a sensitivity ranging from 16.76 mA/K (−100 V) to 27.94 mA/K (−5 V). The experimental results can be interpreted well by the two-dimensional variable range hopping model.