THEORY OF DEFECT STABILITY AND SELF-DIFFUSION MECHANISM IN CARBON-DOPED GAAS

Abstract

The defect stability and the diffusion mechanism of C in GaAs are investigated through ab initio pseudopotential calculations. The most predominant defect is found to be a C-AS acceptor. Lattice relaxations around the substitutional C(As) defect are significant. Thus, the C(As) defect is energetically quite stable, which may explain the low diffusivity of C observed in GaAs. However, as the C concentration exceeds above 10(19) cm-3, the concentration of [100]-split interstitial C-C complexes increases abruptly. This C-C complex compensates for hole carriers and affects the diffusion process of C.