The incorporation of Br into these III-V compounds, and its interaction with defects, was studied by using the perturbed angular correlation technique and a 77Br(77Se) probe. A uniform quadrupole interaction frequency of 299MHz, with an axially symmetrical electric field gradient (principal component, Vzz; oriented along <111>), was observed at the site of all of the probes in semi-insulating GaAs after annealing at 1123K. The appearance of the 299MHz interaction was studied as a function of the dependence of the charge state of the probe. Thus, perturbed angular correlation experiments were performed on various pre-doped GaAs crystals. It was found that, whereas in weakly n-doped and p-doped samples no change in the interaction parameters was observed, a new quadrupole interaction was detected in a highly p-doped GaAs sample (with a quadrupole interaction frequency of 165MHz). The microscopic environment of the Br probe was also studied in other III-V compounds. In the case of InP, after annealing at 1023K, a large fraction of the probes was subjected to a uniform quadrupole interaction (with a quadrupole interaction frequency of 170MHz); similar to the situation in GaAs. In the case of InAs, all of the probes were found in a cubic environment after annealing at 923K.

M.Wehner, P.Friedsam, R.Vianden, S.Jahn, D.Forkel-Wirth: Materials Science Forum, 1995, 196-201, 1419-24