PAC studies of implanted 111Ag in single-crystalline ZnO

The local environment of implanted Ag-111 (t(1/2)=7.45 d) in single-crystalline [0001] ZnO was evaluated by means of the perturbed angular correlation (PAC) technique. Following the 60 keV low dose (1x10(13) cm(-2)) Ag-111 implantation, the PAC measurements were performed for the as-implanted state and following 30 min air annealing steps, at temperatures ranging from 200 to 1050 degrees C. The results revealed that 42% of the probes are located at defect-free S-Zn sites (nu(Q)similar to 32 MHz, eta=0) in the as-implanted state and that this fraction did not significantly change with annealing. Moreover, a progressive lattice recovery in the near vicinity of the probes was observed. Different EFGs assigned to point defects were Furthermore measured and a general modification of their parameters occurred after 600 degrees C. The 900 degrees C annealing induced the loss of 30% of the Ag-111 atoms, 7% of which were located in regions of high defects concentration.