Improved response speed of β-Ga2O3 solar-blind photodetectors by optimizing illumination and bias

Abstract

Ga2O3-based solar-blind ultraviolet photodetectors (PDs) have stimulated extensive attention for covering both civilian and military applications. During the past decade, Ga2O3-based solar-blind PDs have made a great progress in key metrics such as responsivity, detectivity and gain. However, they still suffer from relatively slow response time, from milliseconds to seconds. The trapping states at the surface/interface are believed to contribute to the low response speed. Besides the intrinsic factors, external factors including the illumination and bias voltage also have an important influence on the photoresponse speed. However, there is no in-depth analysis of illumination and bias impact on the photoresponse properties. Herein, we present an experimental investigation on the illumination intensity and bias voltage modulating response speed in a typical Ga2O3-based photoconductive PD. The photoresponse time can be accelerated up to two orders by varying the illumination and bias. The superior photoresponse capabilities of the Ga2O3-based PDs can be ascribed to the light controllable trap/de-trap processes as well as electric field accelerated carrier transport. The study offers clear images of the charge diffusion and drift process in the photodetector upon external stimuli, which will aid to optimize the performance of Ga2O3-based PDs.