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 heterostruc tures grown by molecular beam epitaxy in a chamber where group-III arsenide s are also prepared, was investigated by high resolution x-ray diffraction measurements. The incorporation was determined by measuring the lattice mis match between GaSb substrates and the possibly As-contaminated GaSb buffer layers in several structures containing layers with different Al concentrat ion. The largest As molar fraction value measured is 0.000 43. The effect o f the As incorporation on the deviation from Vegard's law, as previously fo und in the AlGaSb epitaxial system, was considered. From this analysis it w as possible to confirm the nonlinear variation of the lattice constant vers us the Al content, as previously determined. (C) 2001 American Institute of Physics.