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

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 degrees C, at which the strong neutral acceptor bound exciton (A(0)X) 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.