Determination of epitaxial Al_xGa_1-xAs composition from x-ray diffraction measurements

Abstract

The correlation between the aluminum composition in epitaxial Al xGa1-xAs and double crystal x-ray diffraction measurements was quantitatively determined. The angular separation ΔΘ, between the diffraction peaks from the AlxGa1-xAs layer grown by metalorganic vapor phase epitaxy and the GaAs substrate increased nonlinearly with the Al content, which was independently determined using photoluminescence and electron microprobe measurements. The calibration curve was used to determine AlAs materials parameters. The AlAs lattice constant and Poisson ratio were determined to be 5.6622 Å and 0.275, respectively, assuming that the GaAs parameters are 5.65325 Å and 0.311.