High-performance photoresponsivity and electrical transport of laterally-grown ZnO/ZnS core/shell nanowires by the piezotronic and piezo-phototronic effect

Abstract

The electrical and optical sensing properties of laterally-grown ZnO/ZnS core/shell nanowires (NWs) are remarkably enhanced by applying an external strain, compared with those of ZnO NWs. The strain-induced piezopolarization charges, together with spatial separation of the charge carriers resulting from the type-II band structure of the ZnO/ZnS core/shell NWs, can effectively modulate the carrier transport at the junction interface between the NWs and remarkably increase the photocurrent under ultraviolet irradiation because of band realignment. Herein, the feasibility of laterally-grown ZnO/ZnS core/shell NWs are demonstrated as electrical and photo-sensing devices with high-performance features by showing the enhanced electrical transport characteristics, as well as the high photoresponsivity via the influence of external strain combined with the type-II band structure of ZnO/ZnS core/shell NWs, when compared with those of ZnO NWs. The output current (3.01×10−5A) and photoresponsivity (1.19×102A/W) of ZnO/ZnS core/shell NWs under a tensile strain of 0.3% are 8.93 and 23.9 times higher, respectively, than those of ZnO NWs (3.37×10−6A and 4.96A/W, respectively) under the tensile strain of 0.3%.