Trap assisted charge multiplication enhanced photoresponse of Li-P codoped p-ZnO/n-Si heterojunction ultraviolet photodetectors

Abstract

In this work, we report a high-performance p-ZnO/n-Si heterojunction-based ultraviolet (UV) photodetector fabricated by dual ion beam sputter deposition. The lithium-phosphorus (Li-P) codoping route was used to realize low resistive and stable p-type ZnO. The current-voltage characteristics of p-ZnO/n-Si heterojunction photodiode showed good rectifying behavior with a rectification ratio of 170 at ±3 V. The spectral response measurements of the photodiode showed excellent responsivity with a peak observed around ∼325 nm and cutoff wavelength around 370 nm. The maximum responsivity achieved was 2.6 A W-1 at an applied reverse bias of -6 V. The external quantum efficiency determined was of the order of ∼1000% which is attributed to the trap assisted multiplication of charge carriers. © 2017 IOP Publishing Ltd.