The saturation behavior of the free carrier concentrations in p-type InP monocrystals which had been doped by Zn diffusion was investigated. The maximum free-hole concentration appeared at about 5 x 1018/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. In InP, the substitutional state of Zn depended upon the cooling rate of the sample after high-temperature diffusion. In slowly cooled samples, a large fraction (about 90%) of the Zn atoms formed random precipitates of Zn3P2 and elemental Zn. However, after rapid cooling, only 60% of the Zn atoms formed such precipitates while the remainder occupied specific sites. The results were analyzed in terms of the amphoteric native defect model. It was shown that differences in the electrical activities of Zn atoms were a consequence of 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