Double-crystal X-ray diffraction and infra-red absorption measurements were performed on C-doped low-temperature GaAs layers which had been grown by means of solid-source molecular beam epitaxy using various growth temperatures and C concentrations. Strain compensation was achieved at 220C and a C concentration of 2.5 x 1019/cm3. The density of AsGa antisite defects, and the incorporation of C, was studied. At 250C, and high C concentrations, a sharp decrease in the intensity of the local vibrational mode of substitutionally incorporated CAs was observed. At the same time, new local vibrational modes appeared whose intensity increased upon further lowering the growth temperature. This behaviour, which was not observed at low C concentrations nor in heavily-doped GaAs:C grown at normal growth temperatures, was attributed to the formation of C-C complexes in heavily-doped C-doped low-temperature GaAs.

Growth and Characterization of Carbon-Doped Low-Temperature GaAs. J.Herfort, W.Ulrici, M.Moreno, K.H.Ploog: Journal of Crystal Growth, 2002, 237-239, 1440-4