(a) X-ray diffraction longitudinal scans on an as-deposited sample (lower solid line) and on a sample annealed for 2 h under Ar atmosphere (upper/black solid line). Peaks corresponding to crystalline planes on the SiGe structure are indicated. Vertical dashed lines correspond to the expected positions of the diffraction peaks of a pure crystalline Ge reference measured at room temperature. (b) Anomalous X-ray diffraction in the vicinity of the 220 and 311 reflections at two energies close to the Ge K-edge: 11 003 eV (solid line) and 11 097 eV (dotted line). The variation of the dispersion correction f′ for the atomic scattering factor of Ge is shown in the inset. At these two energies the absorption correction f′′ for Ge does not vary significantly, while the Si atomic scattering factor remains constant (see text for details).