Electron Bombardment Induced Photoconductivity and High Gain in a Flat Panel Photodetector Based on a ZnS Photoconductor and ZnO Nanowire Field Emitters

Abstract

Flat panel photodetectors are widely studied and implemented in large-area imaging. However, developing highly sensitive flat panel photodetectors with high internal gain is still very challenging due to material limitation where photoelectron multiplication mechanisms have to be established. In this study, we proposed to use an electron bombardment induced photoconductivity (EBIPC) mechanism to achieve high internal gain in a flat panel photodetector based on a ZnS photoconductor integrated with ZnO nanowire (NW) field emitters. The photoconductivity of the ZnS thin film increased significantly upon bombardment with electrons from the emitters, which led to an internal photoconductive gain of above 104 in a wide wavelength range. The photoresponse behaviors under different device parameters further verified that the high gain depended on the enhanced light-responsive performance of the ZnS thin film induced by the EBIPC mechanism. The proposed EBIPC mechanism is promising for use in flat panel photodetec...