Effects of heat treatment on the 0.8 eV photoluminescence emission in GaAs grown by molecular beam epitaxy at low temperatures

We report 0.8 eV photoluminescence (PL) emission of GaAs grown at low temperatures between 325 and 400°C by molecular beam epitaxy. Effects of heat treatments of the 0.8 eV emission are compared with those of the 1.467 eV sharp bound exciton lines. This allows us to attribute the 0.8 eV emisson to the As-V_Ga center. We discuss the assigning of the As_i-V_Ga center to the well-known EL6. The PL intensity variation of 0.68 eV EL2 and 0.8 eV As_i-V_Ga seen in substrate materials is explained in terms of dislocation−mediated As_i-V_Ga transformation to EL2 whereas the PL intensity variation of 0.8 eV As_i-V_Ga for molecular beam epitaxy layers can be attributed to the growth condition.