Probing grain boundaries in As-doped polycrystalline silicon

Using In-111-Cd-111 perturbed angular correlations, we investigated the beh aviour of In in heavily As-doped polycrystalline silicon. The nuclear In tr acers were either introduced by means of grain boundary (GB) diffusion or i on implantation. We find, that the in-diffused In tracers exclusively probe GBs which give rise to a broad distribution of static quadrupole frequenci es. The implanted tracers exclusively probe Si bulk material, where they en counter As-dopants during thermal annealing and form the well-known In-As c omplexes #1 and #2, and the previously unknown complex #4 (eQV(zz) = 117 MH z, eta = 0) which involves three As atoms on nearest neighbor sites with re spect to the probe. The implications of the present experiment on acceptor doping and GB probing are discussed.