Lattice vibrations of Si1-xCx epilayers on Si(100) -: art. no. 115308

Raman spectroscopy has been used to investigate the lattice vibrations of Si1-xCx (0<x<0.02) epilayers grown on Si(100) by electron cyclotron resonance plasma-assisted molecular beam epitaxy. Spectral contributions due to first- and second-order longitudinal and transverse optic phonons together with disorder-induced features have been evaluated by a detailed polarization and C concentration dependence analysis. The band parameters exhibit generally a linear dependence on x. A Raman line observed near 630 cm(-1), which in past work has been associated with C ordering in the Si lattice, is found not to agree with this interpretation. It is associated with interstitial C. The optical absorption coefficient near 458 nm is deduced from the Raman intensity information, and is found to increase significantly with increasing x.