Point Defects and Diffusion in Semiconductors

Summary

In silicon, both vacancies and self-interstitials are present under thermal equilibrium conditions. They contribute to silicon self-diffusion and diffusion of most impurity and dopant atoms. The diffusivities and thermal equilibrium concentrations of self-interstitials and vacancies in Si are not reliably known: the estimated values spread over many orders of magnitude. The conclusions reached in this article, which has dealt with the behavior of point defects in silicon at high temperatures (>500°C), however, cannot yet be satisfactorily reconciled with low-temperature results involving irradiation-induced point defects. In GaAs, negatively charged Ga vacancies and positively charged Ga self-interstitials dominate self- and impuritydiffusion. Knowledge on intrinsic point defects and diffusion mechanisms involving the As sublattice is very limited. The concepts developed for intrinsic point defects and diffusion processes in GaAs are likely to be applicable to studies of InP and other III-V compounds as well.