Annealing behaviour of GaN after implantation with hafnium and indium

The annealing behaviour of GaN after implantation of Hf-181 and In-111 was studied using the perturbed angular correlation (PAC) technique. During, an nealing most Hf probes are built in on substitutional Ga sites and the leve l of lattice damage decreases with annealing temperature T-A. In the case o f In the results also show a good recovery of the crystal lattice. However a large variation of the quadrupole interaction frequency is observed indic ating a considerable change in the local lattice geometry. The dependency o f this variation on the implantation dose is investigated. The values deriv ed for the electric field gradients at the probe sites are compared to valu es determined by NMR measurements.