Temperature dependence of the pyro-phototronic effect in self-powered p-Si/n-ZnO nanowires heterojuncted ultraviolet sensors

Self-powered pn-juncted devices fabricated with pyroelectric semiconductor have attached much attention as active ultraviolet (UV) photodetectors (PDs), featuring with energy-efficient, active functionality and ultrafast response speed. Herein, the pyroelectric ZnO nanowires (NWs) grown on p-Si are functioned as a self-powered UV PD. Without an external voltage, the fabricated device exhibits a stable and uniform UV sensing ability with high photoresponsivity and fast response and decay time. Furthermore, the effects of ambient temperature on the self-powered UV PD are systematically investigated. Under the temperature of 77 K, the current response of the UV PD is significantly improved by over 1304%, while it is only increased by 532.6% at RT. Under the temperatures above RT, the UV PD functions well in a self-powering and stable manner even the temperature is elevated to 85 degrees C from RT, exhibiting good photoresponsivity of 17.0 mA/W and fast response time of 700 mu s at the rise edge. By analyzing energy diagrams of the pn junction, the underlying physical mechanism of the self-powered UV PDs is carefully illustrated. This study provides guiding significance for research of high-performances UV sensing and ultrafast optoelectronic communication. (C) 2019 Elsevier Ltd. All rights reserved.