X-ray diffraction analysis of step-graded InxGa1−xAs buffer layers grown by molecular beam epitaxy

High resolution X-ray diffraction reciprocal space mapping (RSM) is used to study the crystal quality of step-graded InxGa1−xAs buffer layers grown on GaAs (0 0 1) substrates by molecular beam epitaxy (MBE) using two growth methods. The lateral correlation length of the buffer layers are described by the FWHM of diffraction peaks along the lateral directions extracted from RSM, which are good indicators of the layer's crystalline quality. The quality improvement of InxGa1−xAs buffer layers grown at low temperature with in-situ annealing could be determined by XRD-RSM, which is also consistent with TEM results.