Fundamental reactions controlling anion exchange during mixed anion heterojunction formation: Chemistry of As-for-Sb and Sb-for-As exchange reactions

As-for-Sb and Sb-for-As anion exchange reactions are investigated in a molecular beam epitaxy environment, where the GaSb surfaces are exposed to [As.sub.2] and [As.sub.4] species and the GaAs is exposed to [Sb.sub.2], respectively. The As-for-Sb anion exchange reaction competes with the formation of isoelectronic As[Sb.sub.y] compounds and the Sb-for-As anion exchange does not occur due to the low diffusivity of Sb into GaAs.