Influence of As incorporation on the deviation from Vegard's law in the AlxGa1-xSb/GaSb system

A possible unintentional incorporation of As in AlxGa1-xSb/GaSb heterostructures grown by molecular beam epitaxy in a chamber where group-III arsenides are also prepared, was investigated by high resolution x-ray diffraction measurements. The incorporation was determined by measuring the lattice mismatch between GaSb substrates and the possibly As-contaminated GaSb buffer layers in several structures containing layers with different Al concentration. The largest As molar fraction value measured is 0.000 43. The effect of the As incorporation on the deviation from Vegard's law, as previously found in the AlGaSb epitaxial system, was considered. From this analysis it was possible to confirm the nonlinear variation of the lattice constant versus the Al content, as previously determined. (C) 2001 American Institute of Physics.