OBSERVATION OF A TRICLINIC LATTICE DISTORTION OF INXGA1-XAS (100)-ORIENTED EPITAXIAL LAYERS BY HIGH-RESOLUTION DOUBLE-CRYSTAL X-RAY-DIFFRACTION

In this work the lattice distortion of InxGa1-xAs epitaxial layers with different InAs mole fractions (0.08 < x < 0.28), grown on (100)-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 (400), (422) and (531) 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 (100) substrate surface was less than 0.2-degrees.