Composition profiling of a SiGe island. (a) Experimental (black) and reconstructed (red) Raman spectra. The blue spectra are the weighted ϕ
components. (b) Relative spectral contributions, a
, with respect to the composition. (c) Composition profile inside each island modeled as a multilayer. The distance from the substrate surface is z. The uncertainty on the thickness values by Raman spectroscopy is about 10% of the total thickness. The data are compared to AFM and X-ray results of similar islands. In the inset of panel (c), the AFM profile of one island is reported.