Enhancing responsivity of ZnO nanowire based photodetectors by piezo-phototronic effect

Abstract

A promising approach was proposed to enhance the responsivity of a ZnO nanowires array based photodetector with metal-semiconductor-metal structure through piezo-phototronic effect. The ZnO nanowires arrays were synthesized via hydrothermal method to function as both piezoelectric and light-trapping layer. The photoresponses of the ZnO nanowires based photodetector were tuned by the modulation of local Schottky barrier heights (SBH) at the metal-ZnO interfaces as a result of strain-induced polarization charges. Subjected to a −0.62% compressive strain, the responsivity of the prepared photodetector was increased by as much as 176%. Furthermore, the devices hydrothermally synthesized at 0.10M have a larger photoresponse and higher stress sensitivity compared to the ones prepared at 0.05M and 0.15M. This work not only strengthens the fundamental understanding of piezo-phototronic effect on photodetectors but also provides an efficient means for optimization/improvement of piezoelectric semiconductor nanowires based optoelectronic devices.