In an embodiment, a method for determining the concentration of an element of a heteroepitaxial layer includes generating a reciprocal space map in Qz and Qx directions in a portion of reciprocal space describing positions of diffracted X-ray peaks of a heteroepitaxial layer and of a substrate on which the heteroepitaxial layer is positioned, determining the position of a diffracted X-ray peak of the substrate in the reciprocal space map in the Qx direction, determining the expected position of the diffracted X-ray peak of the heteroepitaxial layer in the Qx direction based on the determined position of the diffracted X-ray peak of the substrate in the Qx direction, generating a scan of the heteroepitaxial layer in a Qz direction at the expected position in the Qx direction, and determining the concentration of a constituent element of the heteroepitaxial layer based on the scan.