Infra-red absorption and Raman scattering spectra were obtained from Si-doped superlattices which had been grown, by means of molecular beam epitaxy, onto (100) substrates at 400C. The Si areal concentrations were greater than 0.03 of a monolayer. It was found that the superlattices contained SiAs, SiGa-SiAs pairs and Si-X defects, together with the SiGa donors which had been detected previously. Two-dimensional Si-Si covalently bonded clusters, which were attributed to surface aggregation, were detected at Si areal concentrations of more than 0.5 of a monolayer. In order to explain the formation of complexes, it was suggested that displaced SiDX atoms made local diffusion jumps during growth.

R.C.Newman, M.J.Ashwin, M.R.Fahy, L.Hart, S.N.Holmes, C.Roberts, J.Wagner: Materials Science Forum, 1995, 196-201, 425-30