Dopant and defect energetics: Si in GaAs

We calculate the formation energy of Si donors, acceptors, and defect complexes in GaAs. From these energies we obtain the equilibrium concentrations of native defects and Si-defect complexes as well as the total solubility of Si in GaAs. The calculated equilibrium solubility limit of Si is in good agreement with experiment. The (${\mathrm{Si}}_{\mathrm{Ga}}$-${\mathit{V}}_{\mathrm{Ga}}$ ${)}^{2\mathrm{-}}$ complex occurs in relatively high concentrations under As-rich conditions and may therefore mediate Si and Ga diffusion. The donor-vacancy complex is found to be an important mechanism for compensation in heavily doped GaAs.