BOND-LENGTH DISTORTIONS IN STRAINED SEMICONDUCTOR ALLOYS

Extended-ray absorption fine structure measurements performed at In-K edge have resolved the outstanding issue of bond-length strain in semi conductor-alloy heterostructures. We determine the In-As bond length t o be 2.581 +/- 0.004 Angstrom in a buried, 213 Angstrom thick Ga0.78In 0.22As layer grown coherently on GaAs(001). This bondlength correspond s to a strain-induced contraction of 0.015 +/- 0.004 Angstrom relative to the In-As bond length in bulk Ga1-xInxAs of the same composition; it is consistent with a simple model which assumes a uniform bond-leng th distortion in the epilayer despite the inequivalent In-As and Ga-As bond lengths.