Optical Characterization of Si1-xCx/Si ( 0≤x≤0.014) Semiconductor Alloys

We have characterized the optical properties of heteroepitexial Si1-x Cx /Si (0≤x≤0.014) alloys grown on Si substrates by solid phase epitaxy using spectroscopic ellipsometry and photoluminescence. The measured dielectric function confirms that the samples are of good crystalline quality. The 14-K photoluminescence spectra of Si1-x Cx /Si show several defect peaks. After hydrogen passivation, we observed a new peak near 1.15-1.17 eV which increases in energy with the incorporation of carbon. We tentatively assign this peak to the no-phonon peak of the Si1-x Cx epi-layer. We discuss the alloy shift of the observed spectroscopic features in terms of the C-induced change in the Si indirect band gap.