Interface effects on the raman spectra of Si/3C-SiC superlattices

Theoretical calculations are performed on the role of smooth interfaces in the Raman spectra of Si/3C-SiC superlattices. The dispersion relations were obtained using a linear chain model with the alloyed interface δ-(3C-SiC)_0.5(Si)_0.5 described in the virtual crystal approximation. A modified bond-polarizability model was used to calculate the Raman spectra. The main results are the enhancement of the Raman spectra and the appearance of new peaks in between those related to the Si quasi confined and the 3C-SiC-confined modes with increasing number δ of interfacial monolayers (3C-SiC)_0.5(Si)_0.5. Some of the smooth interface related Raman peaks have intensity comparable with those of an abrupt Si/3C-SiC superlattice.