Measurements and Modeling of Zinc Diffusion Profiles in Gallium Phosphide

摘要

We investigated the diffusion behaviour of Zn in GaP under P-deficient ambient conditions in order to obtain information about the diffusion mechanism and the participating native point defects. Zn penetration profiles as measured by secondary ion mass spectroscopy exhibit various anomalous shapes which correlate with the diffusion-induced extended-defect structure as revealed by transmission electron microscopy. For relatively simple defect structures including the defect-free case, the Zn profiles can be numerically described within the framework of a kick-out mechanism involving Ga interstitials Ⅰ_(Ga). In profile fitting allowance is made for Zn self-doping effects, different Ⅰ_(Ga) charge states, and Ⅰ_(Ga) trapping due to extended defects. The resulting Zn-related diffusion coefficients in GaP are compared with similar data for GaAs. The simultaneously obtained Ⅰ_(Ga)-related self-diffusion coefficients are critically discussed with regard to existing Ga tracer diffusion data.