The effect of impurities upon the creation of Ga vacancies in Si-doped material, grown on a Be-doped epilayer by molecular beam epitaxy, was investigated by means of slow positron beam measurements. It was found that doping with Si enhanced the creation of Ga vacancies. The results supported a theoretical model in which the creation of Ga vacancies was explained in terms of a change in the-Fermi level position due to Si doping. It was also suggested that Si atoms diffused as a neutral complex, SiGa-VGa, rather than as SiGa-SiAs. A change in the S-parameter distribution at the interface between Si-doped and Be-doped regions was explained in terms of a so-called Be carry-forward effect which occurred during the growth of Si-doped GaAs on a Be-doped epilayer.

J.L.Lee, L.Wei, S.Tanigawa, M.Kawabe: Journal of Applied Physics, 1990, 68[11], 5571-5