Raman spectroscopy was applied to Si1−x−yGexCy epitaxial layers grown onto Si substrates by ultra-high vacuum chemical vapor deposition. The incorporation of substitutional C atoms reduced the Si–Si mode frequency of Si1−x−yGexCy, whereas the interstitial C incorporation increased it. The ab initio phonon frequency calculations, considering the most stable interstitial C site was performed to verify the results and it was shown that the V-shaped behavior, with decreases and increases in Si–Si mode frequency with the amount of C, originated from the effect of interstitial C incorporation. It was proposed that the Si–Si Raman vibrational mode frequency shift could be used as a tool to observe interstitial C atoms.

Effect of Interstitial C Incorporation on the Raman Scattering of Si1-x-yGexCy Epitaxial Layer. S.Choi, H.W.Kim, H.J.Kim, S.Hong, G.D.Lee, E.Yoon: Applied Physics Letters, 2008, 92[6], 061906