Origin of cooperative transition of antisite-Arsenic defects in Be-doped low-temperature-grown GaAs layers

Abstract

We investigated the origin of the cooperative transition of AsGa atoms in Be-doped low-temperature-grown GaAs layers by magnetization measurements and first principle calculations. For first principle calculations, a large supercell was used to reproduce the average distance of AsGa atoms and Be atoms in experimental samples. With one AsGa atom and Be atom in each supercell and the periodic boundary condition, the calculated total energy of the AsGa at the substitutional site is lower than that at the interstitial site by 0.87eV. The magnetization measurements have shown that the transition occurs in a sample with a GaAs substrate similar to that in lift-off samples, indicating that a uniform strain induced by the substrate does not affect the occurrence of the transition. These results suggest that the complex strain field induced by the coexistence of AsGa defects at substitution and interstitial site plays a major role in the cooperative transition.