Determination of composition, strain, and layer thickness of germanium-tin superlattices using x-ray diffraction

We apply an approach that uses x-ray diffraction (XRD) and dynamical scattering theory to determine the resulting elemental compositions of a Ge1−ySny/Ge1−xSnx superlattice after growth by simulating not just peak location but also the intensity modulation of the satellite peaks of the XRD profile. Analysis of the intensity modulation of the satellite peaks of the XRD profile of a Ge1−ySny/Ge1−xSnx superlattice determined the Sn composition, strain, and layer thickness, revealing a significant exchange of Sn in each layer. The superlattice structure was additionally confirmed by transmission electron microscopy, validating the XRD approach as applicable to superlattices more generally.