Strain relaxation in thin SiGe epilayers doped with carbon

The possibility of obtaining a heterosystem consisting of the upper partially strained and lower relaxed sublayers by stepwise in situ doping of SiGe layers by carbon is considered. The properties of the as-grown and annealed samples are studied by means of Raman spectroscopy and atomic force microscopy. The degree of strain relaxation in the as-grown layers was derived from the Raman spectra. The Si0.7−yGe0.3Cy layer was shown to be stable to annealing up to 700 °C. Moreover, the strain relaxes during annealing not homogenously over the whole structure but in a layer-by-layer way. The segregation of carbon atoms is observed for as-grown Si1−x−yGexCy layers in the near-substrate regions.