SUPPRESSION OF SI-GE INTERFACIAL VIBRATION MODE IN THE RAMAN-SPECTRUMOF A SI6GE4 SUPERLATTICE

A thin SiGe buffer layer grown on a Ge-island-decorated Si(100) surfac e has been prepared and used as the substrate for growing the Si6Ge4 s hort-period superlattice with symmetrically distributed built-in strai ns. The Si/Ge superlattice is found to be free of threading dislocatio ns, which is in favor of suppressing the intermixing of Ge and Si atom s at the superlattice interfaces. The Raman spectrum shows a very weak Si-Ge vibration mode, narrow peak widths of the Ge-Ge and Si-Si modes , and the disappearance of the Si optical-phonon mode from the substra te, which are indicative of the great improvement of the interfacial q uality.