Identification of Vacancy-Type Defects in Molecular Beam Epitaxy-Grown GaAs Using a Slow Positron Beam

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Vacancy-type defects in the GaAs film grown to a thickness of 3000 Å on a GaAs substrate by molecular beam epitaxy (MBE) were studied using a slow positron beam. The Doppler-broadened shape parameters showed a significant difference between the as-grown GaAs film at 450°C and that at 650°C. It is suggested that the higher growth temperature promotes the creation of Ga vacancies in MBE-grown GaAs film. It is also shown that the oxide capped on the surface of GaAs enhances the formation of Ga vacancies during annealing (950°C, 4 s). The Si ion-implanted GaAs could not be recovered completely with subsequent annealing (950°C, 4 s).