Improvement of Photoresponse Properties of Self-Powered ITO/InP Schottky Junction Photodetector by Interfacial ZnO Passivation

Abstract

A self-powered ITO/ZnO/InP heterojunction photodetector has been demonstrated with a 10-nm ZnO interfacial layer deposited by atomic layer deposition as a hole-blocking layer. The presence of a valence band offset between InP and ZnO enhances the photocurrent. The valence band offset between InP and ZnO creates a sufficient barrier for hole movement. Low surface recombination under 520-nm laser irradiation produced maximum photoresponsivity of 44.2 mAW(-1) with an illumination power of 1 mu W at zero bias. The ZnO-passivated self-powered photodetector shows fast response and improved photo-detecting properties. Furthermore, the highly sensitive photodetectors are demonstrated to record the heart pulse wave by measuring relative changes in blood volume of the finger vessels.