DETERMINATION OF THE SB COMPOSITION PROFILE IN MBE-GROWN GASB GAAS STRUCTURES BY HIGH-RESOLUTION X-RAY-DIFFRACTOMETRY/

Using high-resolution X-ray diffractometry, we examine the structural and chemical properties of nominally pure GaSb layers in GaAs grown by solid-source molecular beam epitaxy. In thicker films an exponential composition gradient is revealed, with the Sb content reaching 30% aft er 70 nm. Ultrathin GaSb films (a few monolayers) actually contain onl y a few percent Sb, i.e., in the first stage of growth Sb incorporatio n is severly hindered. In contradiction to energetic arguments, we fin d that lowering the growth temperature leads to a decrease of the Sb i ncorporation in the interface region. This finding indicates that the incorporation of the group V atoms in the interface region is strongly affected by kinetic processes.