Simulations of Bragg diffraction of a focused x-ray beam by a single crystal with an epitaxial layer

Abstract

The Bragg case diffraction of a narrow x-ray beam in a multilayer crystal is studied theoretically. The beam produced by a parabolic refractive lens is Bragg reflected by a crystalline sample and a spatial distribution of the intensity is recorded by a detector placed at the focus of the lens. This x-ray optical scheme represents a topographic technique which is extremely sensitive to a depth variation of a crystalline structure. Simulations of the intensity pattern were performed by using a computational technique based on a convolution of individual propagators by performing a double fast Fourier transform procedure. It was shown that each interface in a multilayer crystal can be observed on the intensity pattern with a contrast depending on the incident angle. Thus, by recording a series of images at different angles, valuable depth sensitive structural information can be obtained.