Toward Understanding the Role of VZn Defect on the Photoconductivity of Surface-Passivated ZnO NRs

Abstract

The point defects in ZnO nanorods (NRs) play very crucial role in its photoconductivity (PC) properties and thus it is essential to understand the sub-band gap carrier dynamics in order to have efficient ultraviolet (UV) photodetection. In order to understand the role of a dominant point defect, Zn vacancy (VZn) which is prevalent on the surface of the NRs, we employ a high temperature annealing step in air and also an excess hydration step for one set of annealed NRs, each followed by a final surface passivation step by poly-vinyl butyral (PVB). A comprehensive study on the photocurrent spectra, photocurrent transients under different sub-band gap excitations and power dependence of photocurrent of aqueous chemically grown ZnO NRs treated under various conditions have been carried out and demonstrates the superiority (extraordinarily high and fast UV response) of the point defect rich but surface passivated NRs as compared to ones with absence or less VZn defects. Further a good support on the major role...