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As a kind of photodetector, position-sensitive-detectors (PSDs) have been widely used in noncontact photoelectric positioning and measurement. However, fabrications and applications of solar-blind PSDs remain yet to be harnessed. Herein, we demonstrate a solar-blind PSD developed from a graphene/Ga2O3Schottky junction with a 25-nanometer-thick Ga2O3film, in which the absorption of the nanometer-thick Ga2O3is enhanced by multibeam interference. The graphene/Ga2O3junction exhibits a responsivity of 48.5 mA/W and a rise/decay time of 0.8/99.8 μs at zero bias. Moreover, the position of the solar-blind spot can be determined by the output signals of the PSD. Using the device as a sensor of noncontact test systems, we demonstrate its application in measurement of angular, displacement, and light trajectory. In addition, the position-sensitive outputs have been used to demodulate optical signals into electrical signals. The results may prospect the application of solar-blind PSDs in measurement, tracking, communication, and so on.

The quest for solar-blind photodetectors (SBPDs) with exceptional optoelectronic properties for imaging applications has prompted the investigation of SBPD arrays. Ga2O3, characterized by its ultrawide bandgap and low growth cost, has emerged as a promising material for solar-blind detection. In this study, SBPD arrays were fabricated by weaving Sn-doped β-Ga2O3microbelts (MBs). These MBs, which have a conductive core surrounded by a high-resistivity depletion surface layer resulting from the segregation of Sn and oxygen, are woven into a grid structure. Each intersection of the MBs functions as a photodetector pixel, with the intersecting MBs serving as the output electrodes of the pixel. This design simplifies the readout circuit for the photodetector array. The solar-blind photodetector array demonstrates superior solar-blind detection performance, including a dark current of 0.5 pA, a response time of 38.8 μs, a light/dark current ratio of 108, and a responsivity of 300 A/W. This research may provide a feasible strategy for the fabrication of photodetector arrays, thus pushing forward the application of photodetectors in imaging.

The usage of ZnO as active layers to fabricate hybrid heterojunction light-emitting diodes is expected to be an effective approach for ultraviolet light sources. Individual ZnO microwires with controlled gallium (Ga) incorporation (ZnO/Ga MWs) have been fabricated via a chemical vapor deposition method. It is found that with the increasing Ga-incorporated concentration, the near-band-edge (NBE) photoluminescence of the ZnO MWs blue-shifted gradually from 390 to 370 nm. Heterojunction diodes comprising single ZnO/Ga MWs and p-GaN have been fabricated. With increasing injection currents, the interfacial emissions can be suppressed effectively and the typical NBE emission dominates the electroluminescence (EL). In particular, with increasing Ga-doping concentration, the dominant EL emission wavelengths of the ZnO/Ga MW-based heterojunction diodes blue-shifted from 384 to 372 nm, and the blue shift can be ascribed to the Burstein–Moss effect induced by the Ga incorporation. The present work demonstrates the feasibility of optical band gap engineering of ZnO MWs and the potential application for wavelength-tuning ultraviolet light sources.

The UV–vis photodetector (PD), a detector that can simultaneously detect light in the ultraviolet region and the visible region, has a wide range of applications in military and civilian fields. Currently, it is very difficult to obtain good detection performance in the UV region (especially in the solar-blind range) like in the visible region with most UV–vis PDs. This severely affects the practical application of UV–vis broad-spectra PDs. Here, a simple sandwich structure PD (SSPD) composed of β-Ga2O3, Au electrodes, and the MAPbBr3perovskite is designed and fabricated to simultaneous enhance the detection performance in the UV and visible light regions. The β-Ga2O3/Au/MAPbBr3SSPD exhibits enhanced optoelectronic performance with high responsivities of 0.47 and 1.43 A W–1at 240 and 520 nm under a bias of 6 voltage (V), respectively, which are 8.5 and 23 times than that of the metal–semiconductor–metal (MSM) structure MAPbBr3PD at 6 V, respectively. The enhanced performance was attributed to the effective suppression of carrier recombination due to the efficient interface charge separation in the device structure. In addition, the self-powered response characteristic is also realized by forming a type-II heterojunction between β-Ga2O3and MAPbBr3, which gives the β-Ga2O3/Au/MAPbBr3SSPD superior single-pixel photo-imaging ability without an external power supply. This work provides a simple and effective method for the preparation of high-performance self-powered imaging PDs in the UV–visible region.

Herein, bandgap tuning of monoclinic (−201)‐oriented β‐(AlxGa1−x)2O3thin films is achieved through a β‐Ga2O3/Al2O3heterojunction by a feasible annealing process with an O2atmosphere. During the annealing process, Al atoms of the Al2O3substrate outdiffuse easily into the β‐Ga2O3thin film deposited by ozone‐assisted molecular beam epitaxy (OMBE). The Al compositions in the β‐(AlxGa1−x)2O3samples are tuned through adjusting the annealing temperature from 800 to 1300 °C and experimentally determined from the result of X‐ray photoelectron spectroscopy (XPS) measurements combined with Vegard's law. Successive Al‐composition‐gradient β‐(AlxGa1−x)2O3thin films with controlled bandgap are constructed. On these bases, β‐Ga2O3thin films are deposited on β‐(AlxGa1−x)2O3(0 ≤ x≤ 0.65) substrates through OMBE, yielding β‐Ga2O3/β‐(AlxGa1−x)2O3(0 ≤ x≤ 0.65) heterojunction structures, and the band offsets of this heterojunction are determined by XPS accordingly. This methodology to achieve high‐quality β‐(AlxGa1−x)2O3thin films with adjustable Al composition and tunable band offsets of the β‐Ga2O3/β‐(AlxGa1−x)2O3interface will provide guidance for potential strategies to develop and fabricate β‐(AlxGa1−x)2O3‐based deep‐UV photodetectors and power devices. Bandgap tuning of monoclinic (−201) oriented β‐(AlxGa1−x)2O3thin films are achieved through β‐Ga2O3/Al2O3heterojunction by a feasible annealing process. A successive Al composition‐gradient β‐(AlxGa1−x)2O3thin films with bandgap values controll are conducted. On these basis, β‐Ga2O3thin films are deposited on β‐(AlxGa1−x)2O3substrates through OMBE, yielding β‐Ga2O3/β‐(AlxGa1−x)2O3heterojunction structures, and the band offsets of this heterojunction are determined.

A low‐resistance Ohmic contact of Pd/Pt/Au metallization scheme is formed on a p‐type GaN film grown by metal‐organic chemical vapor deposition (MOCVD). Two samples are prepared to explore the effect of contaminations at the metal and GaN interface on the properties of the Ohmic contact. One directly transfers the fresh GaN film from MOCVD to the metal deposition chamber through an ultrahigh vacuum (UHV) tube, without exposing the GaN surface to air; the other transfers the GaN film from MOCVD to metal deposition through the atmosphere. The results show a lower specific contact resistance (6.2 ± 0.9) × 10−5Ω cm2for the directly UHV‐transferred sample than the air‐transferred sample (2.1 ± 0.9) × 10−4Ω cm2. Once exposed to air, carbonaceous particles and an amorphous oxide layer easily adhere to the p‐type GaN surface, which not only increase the Schottky barrier height but also generate more grain boundaries in the Pd/Pt/Au stacks. The grain boundaries, acting as diffusion channels, make Au atoms diffuse easily into the Pd layer and propagate to the p‐GaN surface layer after annealing. Therefore, the Ohmic contact fabricated in UHV ambience with lower oxygen and carbon contaminations at the interface shows superior characteristics than the samples prepared by the traditional method. Samples transferred via ultrahigh vacuum (UHV) with fewer contaminations at the interfaces of metal/GaN demonstrate lower specific contact resistance, higher reliability, and thermal stability than samples transferred through air with more C/O contaminations.

Growth mechanism and temperature of monoclinic gallium oxide (β‐Ga2O3) films grown by ozone molecular beam epitaxy (MBE) are investigated herein. Phase‐pure (2¯01) β‐Ga2O3films can be grown on c‐plane sapphire substrates when the growth temperature exceeds 500 °C, and the grain size increases with the increase in the growth temperature. Sixfold rotational domains are obtained based on the epitaxial relationships (Ga2O3< 010>//Al2O3<11¯00> and Ga2O3< 102>//Al2O3< 112¯0>). For the film grown at 700 °C, the threefold facets are observed for the first time, which are resulted from the easy‐cleaved (100) plane and rotational domains. In addition, the cathodoluminescence spectra of the β‐Ga2O3films show that the proportion of ultraviolet emission increases with the increase in the growth temperature, which is attributed to the modulation of defect. Finally, the growth rate can be modulated by the ratio of Ga flux and ozone pressure. A reference is provided for heteroepitaxy of β‐Ga2O3films and better understanding of the ozone MBE growth mechanism of oxides. β‐gallium oxide (β‐Ga2O3) films are grown on c‐plane sapphire substrates using molecular beam epitaxial technique with pure ozone as the oxygen source. For the film grown at 700 °C, threefold facets are first observed as the distinct feature of surface morphology, which can be formed due to the easy‐cleaved (100) plane and rotational domains.