This method can be used to determine the composition of strained layers. Shown in Figure 2 are theoretical HR-XRD scans from two samples consisting of 30nm of Si on 14nm of SiGe on Si. In one case there is 6% Ge in the lattice, while in the other case there is 10% Ge. HR-XRD can easily resolve the difference between these two structures as well as determine the thickness of the layer from the thickness fringes.
Furthermore, advanced modeling can provide accurate descriptions of features such as graded SiGe layers. A wide variety of epitaxial materials can be measured with HR-XRD, such as AlGaAs, InGaAs, InGaN, etc. Typically XRD can determine the composition of such layers to within 1 atom%, however, it should be noted that HR-XRD assumes that all of the dopant is present in the lattice.