High-performance self-powered ultraviolet photodetector based on Ga2O3/GaN heterostructure for optical imaging

Gallium oxide (Ga2O3) has attracted much attention for its ultra-wide band gap and superior optoelectronic properties in the field of ultraviolet (UV) photodetectors. However, Ga2O3-based photodetectors still face problems such as slow response speed, large dark current and high power consumption. In this work, we design an n-Ga2O3/p-GaN vertical heterojunction in a transverse device and use it to construct a high-performance UV photodetector. The GaN film directly connects to the electrodes, while the Ga2O3 nano -wires cover the top surface of the GaN and do not contact with any electrode. Based on this unique het-erostructure, the photodetector demonstrates a low dark current and fast photoresponse speed under 254 nm irradiation. On the other hand, the photodetector can be operated at 0 V bias due to asymmetric Schottky barriers caused by the difference in electrode size. The photoresponse, specific detectivity and photoresponse speed of the photodetector are calculated to be 44.98 mA/W, 5.33 x 1011 Jones and 383 ms, respectively, under self-powered mode. The enhanced UV photoresponse and self-powered mechanism of the photodetector are discussed in detail via the schematic diagrams of energy band structure and carrier transport process. At last, a vivid image is obtained using the Ga2O3/GaN photodetector as an imaging pixel in the imaging system. This work provides an effective strategy to construct high-performance UV pho-todetectors toward optical imaging.(c) 2023 Elsevier B.V. All rights reserved.