Optical and electrical properties of individual p-type ZnO microbelts with Ag dopant

Abstract

P-type ZnO microbelts were successfully synthesized by thermal diffusion of Ag in a step by step thermal annealing process. The effect of the annealing temperature on the room temperature photoluminescence (RT-PL) and current versus voltage (I–V) properties of Ag-doped ZnO microbelts were studied. With the increase of the annealing temperature, the deep-level emission (506 nm) decreased and the Ag_Zn related violet emission peak at 405 nm was observed. The substitution of Zn atoms by Ag atoms is unstable at high temperature, which might be a limitation for Ag as the dopant of ZnO. In our experiment, the optimal annealing temperature is 250 °C, at which the strong neutral acceptor bound exciton (A⁰X) peak appeared in the low temperature-PL spectrum. Correspondingly, the conductivity type of the ZnO microbelt transformed from n to p. The symmetrical I–V curves exhibited slightly nonlinear behaviors. The result indicated the existence of Schottky barriers between the individual Ag-doped ZnO microbelt and the In electrodes.