Complemenatary X-ray diffraction and X-ray reflectivity studies on SiGe and SiGe(C) heterostructures

Abstract

High-resolution X-ray diffraction (XRD) and X-ray reflectivity (XRR) measurements were performed and evaluated to study the structural properties of various SiGe/Si and SiGe(C)/Si heterostructures, respectively. The main purpose of the present study was to combine the complementary information content of both X-ray scattering techniques to obtain a sample model that describes both sets of data sufficiently. One main advantage of this combination of techniques is the independent determination of thickness values. XRD in addition is used to evaluate the crystal perfection and interface sharpness of heterostructures. Diffraction patterns of hetero-epitaxial structures contain information about composition and uniformity of epitaxial layers, their thicknesses, the built-in strain and strain relaxation. XRR on the other hand is sensitive to the electron-density profile as a function of depth. It indicates the presence of surface and interface roughness and interlayers regardless of their crystallinity. It is also more sensitive to the near surface region.