First-shell bond lengths in SixGe1-x crystalline alloys

Si and Ge K-edge x-ray absorption fine structure (XAFS) spectra of strained and relaxed SixGe1-x crystalline alloys grown by molecular beam epitaxy on Si(001) substrates are reported. For alloys with less than 30% Si, fluorescence yield detection is shown to be essential to avoid distortions of the Si K-edge XAFS signal caused by the underlying Ge L-edge XAFS signal from the majority Ge species. The average first shell structure has been …