X-ray bragg diffraction profiles from unstrained layered single-crystal structures: Theoretical considerations, simulation and reconstruction using phase-retrieval x-ray diffractometry

The X-ray Bragg diffraction intensity profile for a model strain-compensated single-crystal structure consisting of a thin alloy layer grown on a thick substrate is derived using a Laplace transform interpretation of the kinematical approximation of X-ray diffraction theory, assuming a step-like attenuation depth-profile. The effects of the model physical parameters on the measurable Bragg diffraction intensity profile are discussed. The intensity profiles for model SiGe:C/Si perfectly unstrained layer thicknesses of 50 and 100 nm are simulated for three characteristic X-ray radiation wavelengths (0.05-0.15 nm). The simulations are performed near the absorption edge of Ge to maximise the observable diffraction contrast. The complex structure factor profiles are then reconstructed from the simulated intensity distributions using phase-retrieval X-ray diffractometry (PRXRD) method.