Nonlinear adjustment of the photoresponse of ZnO/a-Ga2O3 heterojunction photodetectors by inserting a SiO2 dielectric layer

Abstract

The detection ability of ZnO/a-Ga₂O₃ heterojunction photodetectors in the solar-blind ultraviolet band has received widespread attention. However, heterojunction photodetectors typically exhibit a low responsivity. In addition, due to the small conduction band shift of ZnO and a-Ga₂O₃, there is a significant dark current in the photodetector under an applied bias voltage. In order to improve the responsivity of the photodetector and reduce the dark current, this paper designs and prepares a ZnO/SiO₂/Ga₂O₃ photodetector. The photodetector exhibits a sudden increase in light response at a bias voltage of 30 V, and exhibits a responsivity of 23.7 A W⁻¹ under 365 nm illumination. Compared with low bias voltage, it exhibits a significant increase in nonlinearity. In addition, the light–dark current ratio of the device under a bias voltage of 20 V increased from 14 to 1000 compared to ZnO/a-Ga₂O₃ PD, indicating that the device has excellent weak light detection ability. This study provides a new strategy for improving the heterojunction barrier height and enhancing the performance of photodetectors.