Observation of a triclinic lattice distortion of InxGa1− xAs (100)-oriented epitaxial layers by high-resolution double-crystal X-ray diffraction

Abstract

In this work the lattice distortion of In x Ga 11− x As epitaxial layers with different InAs mole fractions (0.08 < x < 0.28), grown on (1 0 0)-oriented GaAs substrates by molecular beam epitaxy, is studied in detail by high-resolution X-ray diffractometry. The strain field and the chemical composition are determined by recording rocking curves in different diffraction geometries in the vicinity of the (4 0 0), (4 2 2) and (5 3 1) GaAs reflections. In order to analyze the experimental data we used a 2nd-order approximation of the strain function in the Takagi-Taupin equation. Our results reveal that a triclinic lattice distortion occurs in all of the investigated heterostructures despite the misorientation of the (1 0 0) substrate surface was less than 0.2°.