GALLIUM VACANCY RELATED DEFECTS IN SILICON DOPED GAAS GROWN AT LOW-TEMPERATURES

Point defects and complexes in silicon doped GaAs grown at low tempera tures were investigated. Large differences between the donor and carri er concentrations imply that the crystals contain high concentrations of compensating defects. The detection of Si-Ga-V-Ga pairs confirms th e expectation that they are gallium vacancies and their concentration appears to be controlled by the Fermi level or silicon concentration. The lattice expansion of the low temperature GaAs is related to the co ncentration of As-Ga antisite related defects which do not appear to a ffect significantly the electrical properties of the material. The ann ealing behaviour may be explained by the nucleation of Si clustering b y V-Ga related defects.