Effect of copper and silver co-doping on growth behaviour and photoelectric properties of n-ZnO nanorods/p-GaN heterojunction light-emitting diodes

Abstract

ABSTRACT In order to adjust the band gap of n-ZnO nanorods (NRs)/p-GaN heterojunction and improve its conductivity, a Cu and Ag co-doping ZnO nanorod array has been synthesised on a p-GaN/Al2O3 substrate by a hydrothermal method at low temperature, in addition, investigated the co-doping effect on the morphology, microstructure and electrical/optical properties. Compared with other samples, the average diameter of the co-doped ZnO NRs is larger, and there are fewer NRs per unit area (density). According to X-ray diffraction analysis, the synthesised ZnO NRs had a preferential [001] growth direction and exhibited a hexagonal wurtzite structure. Compared with undoped ZnO NRs, the UV emission peaks of all doped ZnO NRs had a slight red-shift, which may be related to the combined effect of surface resonance and band gap renormalisation effect. Ag+Cu co-doping can also reduce the band gap of the ZnO NRs. The I-V characteristics curve indicates that Ag+Cu co-doping can greatly improve the electrical properties of the heterojunction. This study demonstrates the possibility of ZnO NRs by Ag+Cu co-doping for potential applications in ultraviolet light-emitting diode.