Influence of growth conditions on the As antisites, AsGa 0 and AsGa+ concentrations in the low temperature GaAs MBE growth: A first theoretical study

A novel theoretical investigation is employed to study the influence of surface dynamics in low temperature MBE growth of GaAs. A kinetic growth model along with the charge neutrality equation is used to find the distribution of As antisites between the neutral and charged species using the bulk Ga vacancy concentrations obtained from simulations for the first time. The experimentally observed temperature and as flux dependencies of the As antisite concentrations are successfully reproduced by the model. The As_Ga⁰ and As_Ga⁺ concentrations saturate with As flux for a given temperature due to saturation of an amorphous, physisorbed As surface layer which acts as the reservoir for As antisite incorporation. The As antisite concentration saturates at lower value for higher temperature due to larger evaporation of As antisite from the crystalline state. It is observed that both As_Ga⁰ and As_Ga⁺ concentrations decrease with increase in temperature. While the decrease of As_Ga⁰ concentration with temperature is related to the direct evaporation of As antisite from the crystalline state, the decrease of As_ga ⁺ is related to a decrease in the Ga vacancy concentration