Gallium oxide (Ga2O3) is a representative of ultra-wide bandgap semiconductor, with a bandgap of about 4.9 eV. In addition to a large dielectric constant, excellent physical and chemical stability, Ga2O3 has a breakdown electric field strength of more than 8 MV/cm, which is 27 times than that of Si and about twice larger than that of SiC and GaN. It is guaranteed that Ga2O3 has irreplaceable applications in ultra-high power (1-10 kW) electronic devices. Unfortunately, due to the difficulty of p-type doping of Ga2O3, only unipolar Ga2O3power Schottky diodes are feasible, but substantial progress has been made in recent years. In this article, we review the advanced progresses and important achievements of the state-of-the-arts Ga2O3 based power SBDs, and provide staged guidance for the further development of Ga2O3 power devices. The multiple type of device architectures, including basic structure, edge terminal processing, field plated, trench and heterojunction p-n structure, will be

β-Gallium oxide (β-Ga2O3) has been studied extensively in the past decades due to its excellent ability in fabricating variety of devices, such as solar-blind photodetectors and power devices. However, as an important part in device, the related investigation of β-Ga2O3-metal contact, especially for Schottky contact, are rare. In this review, we summarized the recent research progresses on β-Ga2O3-metal contact, including related theories, measurements, fabrication processes, controlment methods, etc. This review will provide insights for both theoretical understanding of the metal/semiconductor interface, and the fabrication process in engineering applications of Ga2O3 based devices.

Epitaxial growth of a wide bandgap semiconductor β-Ga2O3 thin film with high crystal quality plays a decisive role in constructing optical and electronic devices. However, except for the native substrate, the scarcity of appropriate non-native substrates or the poor crystallization of the deposit in thin film growth severely limits the fabrication and applicability of the final heterostructures and devices. Here, by taking the consistent symmetry and closely matched atomic spacing between β-Ga2O3 (−201) and the cubic perovskite (111)-oriented plane of SrTiO3, we realize the epitaxial growth of single crystal β-Ga2O3 (−201) thin films on the SrTiO3 (111) substrate by the pulsed laser deposition method, as confirmed by wide-range reciprocal-space mapping and high-resolution scanning transmission electron microscopy. The fabricated β-Ga2O3 (−201) photodetector device on the SrTiO3 (111) substrate exhibits excellent ultraviolet optical detection performance with large on/off switching ratios and a fast response speed. Moreover, the β-Ga2O3/SrTiO3 (111) heterojunction shows type-II heterostructure characteristics for energy band alignment, which displays superior ability for electron–hole pairs separation with large conduction and small valance band offsets of 1.68 and 0.09 eV, respectively. The results offer us a new way to obtain high-quality β-Ga2O3 (−201) thin film heterostructures on cubic SrTiO3 (111) substrates and fabricate β-Ga2O3-based optical and electronic devices.

In this paper, a ε-Ga2O3 film/ZnO nanoparticle hybrid heterojunction deep ultraviolet (UV) photodetector is described for 254 nm wavelength sensing application. The constructed ε-Ga2O3/ZnO heterojunction photodetector can operate in dual modes which are power supply mode and self-powered mode. Under reverse 5 V bias with 254 nm light intensity of 500 μW/cm2, the photoresponsivity, specific detectivity and external quantum efficiency are 59.7 mA/W, 7.83×1012 Jones and 29.2%. At zero bias, the advanced ε-Ga2O3/ZnO photodetector performs decent self-powered photoelectrical properties with photo-to-dark current ratio of 1.28×105, on/off switching ratio of 3.22×104, rise/decay times of 523.1/31.7 ms, responsivity of 4.12 mA/W and detectivity of 2.24×1012 Jones. The prominent photodetection performance lays a solid foundation for ε-Ga2O3/ZnO heterojunction in deep UV sensor application.