Extended X-Ray Absorption Fine-Structure Measurement of Bond-Length Strain in Epitaxial Gd sub 2 O sub 3 on GaAs(001)

Extended x-ray absorption fine structure (EXAFS) has been used to measure the bond length in a 23 angstrom epitaxial Gd sub 2 O sub 3 film grown on GaAs(001). The Gd-O bond length is determined to be 2.390 +- 0.013 angstroms, which corresponds to a +0.063 +- 0.013 angstrom increase or a +2.7 +- 0.6% bond-length strain relative to the bond length in bulk Gd sub 2 O sub 3 powder. Using a simple model of the strained film that matches the [001] and [-110] axes of Gd sub 2 O sub 3 with the [110] and [1-10] axes of the GaAs (001) surface, the measured bond-length increase of the film determined by EXAFS agrees well with the perpendicular lattice distortion of the film determined by diffraction.