High sensitivity Ga2O3 ultraviolet photodetector by one-step thermal oxidation of p-GaN films

Abstract

Gallium oxide (Ga2O3), with an ultra-wide bandgap, is a promising semiconductor material for the manufacture of solar blind ultraviolet photodetectors. The Ga2O3 thin films were successfully prepared by simpler feasible one-step thermal oxidation of p-GaN thin films, which were oxidized at 900 °C with varying oxidation times in the environment with an argon-oxygen ratio of 1000. The effect of different oxidation durations on the physical properties of the Ga2O3 thin films was studied, and particularly, the photoelectric performance of the Ga2O3 thin films was further analyzed. Compared with the GaN thin film, the dark current of the photodetector was approximately reduced by 2.31 × 104 times while the photocurrents of the device maintain the same order of magnitude, causing large photo-to-dark current ratios (PDCRs) of 2.29× 104. Furthermore, the device exhibits impressive characteristics such as high responsivity of 2.13 A/W, super high external quantum efficiency (EQE) of 1040.13%, large detectivity (D) of 1.65 × 1011 Jones, and fast response speed of 0.218/0.112 s under UV light illumination of 254 nm wavelength at −5 V bias. The results indicate that the one-step thermal oxidation can be used as a good application for preparing the device with high sensitivity, fast response and the high-resolution detection.