Deviation from vegard law in lattice-matched InGaAs/InP epitaxial structures

The lattice parameters and the composition of InGaAs/InP lattice-matched single heterostructures were independently determined by measuring the high-resolution X-ray diffraction profile and the absorption of the InGaAs layer of the X-ray beam diffracted from the InP substrate. Mass bsorption coefficients taken from recent improvements of the values based on relativistic calculation of X-ray scattering were used. In contrast to previous works in which a linear dependence of the lattice parameters on the composition was suggested, a 6% higher In content in the InGaAs/InP lattice-matched alloy was found. Such results have been confirmed using another method based on the analysis of the X-ray fluorescence of the layer and of standards made of InAs and GaAs finely ground crystals. The results are in good agreement with the predictions of simple models of lattice deformation based on the elasticity theory.