Hybrid reciprocal space for X-ray diffraction in epitaxic layers

Even after several decades of systematic usage of X-ray diffraction as one of the major analytical tool for epitaxic layers, the vision of the reciprocal space of these materials is still a simple superposition of two reciprocal lattices: one from the substrate and the other from the layer. In this work, the general theory accounting for hybrid reflections in the reciprocal space of layer/substrate systems is presented. It allows insight into the non-trivial geometry of such reciprocal space as well as into many of its interesting properties. Such properties can be further exploited even on conventional-source X-ray diffractometers, leading to alternative, very detailed and comprehensive analyses of such materials.