Deep ultraviolet photodetectors based on p-Si/i-SiC/n-Ga2O3 heterojunction by inserting thin SiC barrier layer

Abstract

Deep ultraviolet photodetectors based on p-Si/n-Ga2O3 and p-Si/i-SiC/n-Ga2O3 heterojunctions were fabricated by laser molecular beam epitaxial (L-MBE), respectively. In compare with p-Si/n-Ga2O3 heterostructure-based photodetector, the dark current of p-Si/i-SiC/n-Ga2O3-based photodetector decreased by three orders of magnitude, and the rectifying behavior was tuned from reverse to forward. In order to improve the quality of the photodetector, we reduced the oxygen vacancies of p-Si/i-SiC/n-Ga2O3 heterostructures by changing the oxygen pressure during annealing. As a result, the rectification ratio (I F/I R) of the fabricated photodetectors was 36 at 4.5 V and the photosensitivity was 5.4 × 105% under the 254 nm light illumination at −4.5 V. The energy band structure of p-Si/n-Ga2O3 and p-Si/i-SiC/n-Ga2O3 heterostructures was schematic drawn to explain the physic mechanism of enhancement of the performance of p-Si/i-SiC/n-Ga2O3 heterostructure-based deep UV photodetector by introduction of SiC layer.