Photocurrent dynamics and carrier transport of amorphous-Ga2O3 metal–semiconductor–metal deep ultraviolet photodetectors

This work presents a systematic study in the photocurrent transport and transient dynamics in amorphous Ga2O3-based deep ultraviolet (DUV) photodetectors, which are configured with a co-planar metal–semiconductor–metal structure, with high performances including a DUV/dark current contrast ratio of 106 and a photoresponsivity of 25.3 A/W. Under steady-state DUV excitation, an analytical current–voltage relationship is developed to describe the carrier transport behaviors. Under the pulsed-DUV excitation and post-DUV exposure, the current rise and decay dynamics have been investigated, which enables us to clarify the role of intrinsic defects in the photoresponse and response speed. In addition, we also propose a criterion to adequately evaluate the photoresponsivity of Ga2O3-based DUV photodetectors with slow photocurrent decays.