Density-functional calculations of carbon diffusion in GaAs

Self-consistent-charge density-functional tight-binding (SCC-DFTB) calculat ions have been performed to survey the potential-energy surface for a singl e interstitial carbon atom introduced into GaAs. The results provided a pos sible model for the diffusion of carbon through GaAs with an activation ene rgy of less than 1 eV. The carbon atom moves via split-interstitial and bon d-centered configurations. Subsequently, the energetics of the model reacti on were refined using a fully self-consistent density-functional method, AI MPRO. These calculations were found to be in good agreement With the more a pproximate SCC-DI;TB results. Experimental studies have also found an activ ation energy of similar to 1 eV for carbon migration in heavily doped mater ial. [S0163-1829(99)02246-8].