Self-powered deep ultraviolet PIN photodetectors with excellent response performance based on Ga2O3 epitaxial films grown on p-GaN

Abstract

PIN-type self-powered deep ultraviolet (DUV) photodetectors (PDs) based on Ta doped n-Ga2O3/i-Ga2O3/p-GaN structures with different i-Ga2O3 layer thicknesses were prepared. In the structure, a Ta element in the doped Ga2O3 epitaxial layer should be substitutional doping, which can be confirmed by time-of-flight secondary ion mass spectrometry. With increasing thickness (0–90 nm) of the i-Ga2O3 layer, the crystal quality of the deposited epitaxial films is gradually improved, but the performance of corresponding PDs does not increase monotonically. The PD with an i-layer thickness of c.30 nm under zero bias shows the best response performance such as maximum photoresponsivity (8.67 A/W), good detectability (1.08 × 1014 Jones), and fast response/decay time (86/50 ms) under 222-nm-UV-light illumination. Such good performance should be attributed to the competition between the high photogenerated carriers and the low electric field, whereas the competition is caused by broadening of the depletion region. This research provides an improved and easy method for fabricating high-performance self-powered DUV PDs.