X‐ray rocking curve measurement of composition and strain in Si‐Ge buffer layers grown on Si substrates

The level of strain and the fraction of Ge in SiGe layers grown on Si can be found rapidly and unambiguously using double‐crystal x‐ray diffraction and a simple application of the linear elasticity theory combined with Vegard’s law. The method gives excellent results for 0.4‐μm‐thick buffer layers of SiGe/Si containing 5%–50% germanium. It is shown that lattice relaxation rises abruptly at x(Ge)≥15%, and that some strain remains for x(Ge) as high as 50%.