X-ray triple-crystal diffractometry of defects in epitaxic layers

A new method is developed for calculating the correlation function of the random deformation in heteroepitaxic layers and superlattices from measurements of iso-intensity contours of diffuse X-ray scattering. The method is based on the optical coherence approach and kinematical diffraction theory. Structural models have been found that enable the correlation functions to be calculated for various types of randomly placed defects (mosaic blocks and random elastic deformation). The applicability of the method has been demonstrated by measuring the diffuse X-ray scattering from a ZnTe layer grown on a GaAs substrate. The parameters characterizing the defects were obtained from a comparison of the calculated correlation function with theoretical models.