The defect characterization of heavily Si-doped molecular beam epitaxy-grown GaAs by the monoenergetic positron method

Monoenergetic (100 eV-30 keV) positrons were used as a defect probe for heavily Si-doped GaAs with a thickness of 300nm grown by molecular beam epitaxy (MBE). The Doppler broadening parameters showed quite different profiles for two kinds of samples prepared at 450°C and 650°C, respectively. It is indicated that the surface states are quite different for preserved GaAs and the as-etched one. The high growth temperature introduced point defects with a higher concentration. It is assumed that the defect type of X in the Si-X complex should be a gallium vacancy or a vacancy complex which suppresses the free carrier concentration in heavily Si-doped GaAs.