Perturbed angular correlation spectroscopy was used to investigate In-defect pairs in p-type samples. It was shown that the frequently cited EFG60 signal was not the only one which characterized In-A centers. Depending upon the annealing history of the sample, various electric field gradients with coupling constants of between 49 and 60MHz were observed at 300K. At low temperatures, 2 well-defined electric field gradients (EFG1, EFG2) were measured. After Ag or Cu doping, EFG57 was observed in some samples, and splitting into EFG1 and EFG2 was also sometimes detected at low temperatures. It was concluded that several different electric field gradients which were measured at 300K represented the same probe-defect complex in differing configurations.

U.Reislöhner, N.Achtziger, W.Witthuhn: Journal of Crystal Growth, 1999, 197[3], 576-80