Carrier-capture characteristics of point defects in GaN and ZnO

From the analysis of photoluminescence (PL), we evaluated the carrier-capture and vibrational characteristics for a number of defects in GaN and ZnO. The methods of determining the carrier-capture coefficients are reviewed. The properties of the Zn-Ga acceptor in GaN and the Li-Ga acceptor in ZnO are studied in more detail. The hole-capture coefficient for the LiGa acceptor, responsible for the orange luminescence (OL) band with a maximum at 1.95 eV in ZnO, is estimated to be similar to 6x(10-6) cm(3)/s from the analysis of the OL band thermal quenching; however, a possible temperature dependence of the acceptor energy can reduce this value by at least an order of magnitude. The main parameters of 18 defect-related PL bands in GaN and ZnO are presented.