Strong interface-induced changes on the numerical calculated Raman scattering in Si/3C-SiC superlattices

Raman spectra of (3C-SiC)(8-delta)/(3C-SiC0.5Si0.5)(delta)/(Si)(8-delta)/(3C-SiC0.5Si0.5)(delta) superlattices with interfacial transition regions of thickness delta varying from one to three monolayers are calculated. It is shown that severe frequency shifts (up to -86 cm(-1)) and the flattening of the folded optical phonons dispersion curves are due to the interfacial regions, strongly affecting the Raman spectrum in consequence. With increasing interface thickness, the Raman peaks are enhanced in the middle frequency range. These effects are mainly attributed to localization of atomic displacements at the Si/3C-SiC or the 3C-SiC/Si interfacial transition regions. (C) 2000 American Institute of Physics. [S0003- 6951(00)01948-3].