The saturation behavior of the free carrier concentrations in p-type GaAs monocrystals which had been doped by Zn diffusion was investigated. Free-hole saturation occurred at 1020/cm3. The difference in saturation hole concentrations of materials was investigated by studying the incorporation and lattice location of Zn. The latter was an acceptor when located on a group-III atom site. Zinc was diffused into III-V wafers in a sealed quartz ampoule. Particle-induced X-ray emission and ion-channelling techniques were then used to determine the exact lattice location of Zn atoms. It was found that more than 90% of the Zn atoms occupied Ga sites in diffused GaAs samples. The results were analyzed in terms of the amphoteric native defect model. It was shown that differences in the electrical activities of Zn atoms in various materials were a consequence of the differing locations of the Fermi-level stabilization energy.

L.Y.Chan, K.M.Yu, M.Ben-Tzur, E.E.Haller, J.M.Jaklevic, W.Walukiewicz, C.M.Hanson: Journal of Applied Physics, 1991, 69[5], 2998-3006