Infra-red localized vibrational mode absorption spectroscopy of Si impurities was considered. Absorption lines from SiGa donors, SiAs acceptors, SiGa-SiAs pairs, SiGa-VGa, (Ga vacancy) pairs and a complex Si-X (involving SiAs and VGa) were identified, as well as lines from SiGa-CuGa, SiGa-H, SiAs-H and SiGa-BAs pairs. The observations were related to the electrical properties of n-type Bridgman, liquid-encapsulated Czochralski and molecular beam epitaxial (001) GaAs, and to p-type liquid phase epitaxial and molecular beam epitaxial (111)A layers. The results were attributed to dynamic site switching, effects which were due to counter-doping with shallow acceptors, to the solubility of Si, and to the DX behavior which was observed in homogeneously doped material and had been proposed for -doped molecular beam epitaxial (001) layers. It was concluded that the main problem was to understand the processes which limited the maximum carrier concentration in n-type crystals.

R.C.Newman: Semiconductor Science and Technology, 1994, 9[10], 1749-62