X-ray-reflectivity study of Ge-Si-Ge films

Here we report on an x-ray specular reflectivity study of Ge-Si-Ge trilayers grown on Si(001) single-crystal substrate by ion beam sputtering deposition at various substrate temperatures. The electron-density profile of the trilayer as a function of depth, obtained from x-ray-reflectivity data, reveals an intermixing of Si and Ge. The x-ray-reflectivity data have been analyzed using a scheme based on the distorted-wave Born approximation, and the validity of the analysis scheme was checked using simulated data. Analyzed results provided information regarding interdiffusion in this system. We notice that although the Si-on-Ge interface is sharp, a ${\mathrm{Si}}_{0.4}$ ${\mathrm{Ge}}_{0.6}$ alloy is formed at the Ge-on-Si interface. © 1996 The American Physical Society.