Annealing of zinc-diffused GaAs

Experiments are described in which radioactive zinc is diffused into n-type GaAs at temperatures of 700, 900 and 1000 degrees C. Diffusion profiles are plotted. For certain of the experiments the external zinc vapour source is removed after diffusion has proceeded for 15 minutes and the experiment is continued as a simple annealing stage for a further 15 minutes. Remarkably little further movement of the profile is found during this second stage. This effect is considered and an attempt is made to explain the results in terms of the kinetic processes involved in diffusion from a vapour source. In addition, the profiles permit an accurate value to be obtained for the diffusion coefficient of zinc in GaAs at 700 degrees C and a concentration of 5*10 19 cm -3 .