Crystals of Si-doped material, with free carrier concentrations of between 2 x 1017 and 3 x 1018/cm2, were grown - with and without a B2O3 coating – by using the vertical gradient freeze method. Growth with full encapsulation resulted in etch-pit densities that were lower than 200/cm2; with an X-shaped configuration in crystal wafers. The use of B2O3 led to a reduction in dislocation density, and a decrease in the carrier concentration; combined with B incorporation. Local vibrational mode spectroscopy was used to study the incorporation of Si and B in various as-grown samples which were compensated by electron irradiation. In addition to the local vibrational mode lines of Si-related defects, the modes of BGa, BAs and SiGa-BAs were observed in crystals which had been grown using full encapsulation. The incorporation of B in equal quantities to the Si dopant was suggested to be responsible for the dislocation-reduction.

Study of Silicon-Doped VGF-GaAs by DSL-Etching and LVM Spectroscopy and the Influence of B2O3 Coating C.Hannig, G.Schwichtenberg, E.Buhrig, G.Gartner: Materials Science and Engineering B, 1999, 66[1-3], 97-101