Films of Sb-doped and Sb-free material were grown by means of molecular beam epitaxy at low temperatures, and were annealed at 500 to 900C. The concentrations of As antisites in as-grown samples, which were deduced by using near-infrared optical absorption, were found to be as high as 6 x 1019 and 7 x 1019/cm3 in Sb-doped and Sb-free samples, respectively. The samples were studied by using high-resolution X-ray diffractometry and transmission electron microscopy. In spite of the high concentrations of intrinsic point defects, X-ray rocking curves indicated perfect crystalline quality in as-grown samples. Upon annealing at 500 to 700C, the lattice mismatch decreased in both Sb-doped and Sb-free samples. However, in Sb-doped samples the reduction was much higher than was expected for the antisite defect concentrations which were deduced from optical measurements. Segregation of isovalent Sb impurity into As clusters was suggested to occur. Upon annealing at above 700C, the Sb-doped samples exhibited a marked broadening of the diffraction maximum which was related to the low-temperature GaAs:Sb layer. Transmission electron microscopic and high-resolution X-ray diffraction studies revealed that high-temperature annealing resulted in the formation of dislocation loops which were attached to large As clusters.

Structural Transformations in Low-Temperature Grown GaAs:Sb. D.A.Vasyukov, M.V.Baidakova, V.V.Chaldyshev, A.A.Suvorova, V.V.Preobrazhenskii, M.A.Putyato, B.R.Semyagin: Journal of Physics D, 2001, 34[10A], 15-8