Paper eintragenThe diffusivity was studied by using dimethylzinc as the source in a PH3/H2/N2 atmosphere at 500 to 600C. The results were compared with the Zn doping of material which had been grown via metalorganic vapor-phase epitaxial growth using triethylindium, PH3 and dimethylzinc. It was found that the carrier concentration in Zn-diffused material was lower, by about 2 orders of magnitude, than that in Zn-doped material which had been grown at the same mole fraction. The activation energy for Zn incorporation was deduced to be the same for both diffusion and doping. The observed dependence of the surface carrier concentration upon the diffusion temperature and the mole fraction of dimethylzinc was qualitatively explained by considering an InP surface condensation limit for Zn adsorption. Slightly increased carrier concentrations, after subsequent annealing (500C, PH3/H2/N2 atmosphere) indicated the existence of a low concentration of Zn interstitials in as-diffused InP under a high PH3 flow-rate. The lower carrier concentration of shallow Zn-diffused material, after such annealing, suggested the occurrence of a large out-diffusion of interstitials near to the surface region during annealing.

M.Wada, K.Sakakibara, M.Higuchi, Y.Sekiguchi: Journal of Crystal Growth, 1991, 114[3], 321-6