In this paper, a device structure of high-resistivity-cap-layer HEMT (HRCL-HEMT) is developed for normally-off p-GaN gate HEMT toward high breakdown voltage and low current collapse. It demonstrates that the breakdown capability and current collapse of the device were effectively improved due to the introduction of a thick HR-GaN cap layer. The fabricated HRCL-HEMT exhibits a high breakdown voltage of 1020 V at IDS = 10 μA/mm with the substrate grounded. Meanwhile, the dynamic Ron is only 2.4 times the static Ron after off-state VDS stress of 1000 V with the substrate grounded (the OFF to ON switching time interval is set to 200 μs).

In this letter, gate leakage mechanisms in different gate contact normally off p-GaN/AlGaN/GaN high electron mobility transistors (HEMTs) have been studied by the temperature-dependent current-voltage (I_G-V_G) measurement. It is found that two-dimensional variable range hopping is responsible for gate leakage current at the reverse gate bias and low forward gate bias in both high-leakage and low-leakage Schottky gate contact devices. At high forward gate bias, in the case of high-leakage Schottky contact, the dominant current conduction mechanism is found to be thermionic field emission while it is Poole–Frenkle emission (PFE) for the case of low-leakage Schottky contact and the activation energy of trap states for PFE current is derived as 0.6 eV. Besides, related models are also proposed to describe the gate leakage current in p-GaN gate HEMTs and they match well with the experimental gate leakage current within a wide range of temperatures and gate biases.

In this paper, a solar‐blind ultraviolet photodetector (PD) based on the graphene/vertical Ga ₂ O ₃ nanowire array heterojunction was proposed and demonstrated. To the best of our knowledge, it is the first time that vertical Ga ₂ O ₃ nanowire arrays have been realized. Ga ₂ O ₃ nanowires were obtained by thermally oxidizing GaN nanowires grown by molecular beam epitaxy on n‐doped Si substrate. Then, a monolayer graphene film was transferred to Ga ₂ O ₃ nanowires to form the graphene/vertical Ga ₂ O ₃ nanowire array heterojunction and transparent electrodes. The fabricated device exhibited a responsivity (R) of 0.185 A/W and rejection ratio (R258 nm/R365 nm) of 3×10 ⁴ at the bias of −5 V. Moreover, the fast response times of this PD were 9 and 8 ms for the rise and decay times under 254 nm illumination, respectively, which are attributed to the unique properties of nanowire arrays and the graphene/vertical Ga ₂ O ₃ nanowire array heterojunction structure.

Herein, self‐powered spectrally distinctive UV photodetectors (PDs) based on nanoporous epitaxial Ga₂O₃/GaN heterojunctions grown by metalorganic chemical vapor deposition (MOCVD) are reported. The nanoporous structures are formed by a novel self‐reactive etching (SRE) method, which significantly enhances the device performance. PDs with different porosities are fabricated and compared. In the self‐powered mode, the PD with the highest nanopore porosity exhibits the best performance, with an ultralow dark current of 0.04 nA, a fast photoresponse speed, and a high responsivity of 43.9 mA W⁻¹ (35.8 mA W⁻¹) under 254 nm (365 nm) illumination, which is 800% higher than that of the reference device without the porous structure. Furthermore, opposite current polarities are observed in the PDs under different illumination spectra, the mechanism of which is explained by the carrier transportation using the device band diagrams. This phenomenon can be used to distinguish different incident spectra, opening the door to more new applications. This work represents one of the first spectrally distinctive self‐powered UV PDs based on nanoporous Ga₂O₃/GaN heterojunctions and significantly benefits the development of multifunctional UV PDs.

(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.