Spectroscopic Ellipsometry of Strained Si/Ge Superlattices Grown by Magnetron Sputter Epitaxy

Abstract

AbstractSpectroscopic ellipsometry was used to characterize several short-period SimGen strained superlattices grown on Si(100) substrates or on graded SixGel-x alloy buffers (strainsymmetrization) by magnetron sputter epitaxy, a novel technique with potential application to industry-scale production of epitaxial Si/Ge heterostructures. Ellipsometric spectra were analyzed within a multilayer model, which included an oxide overlayer, in order to derive the effective dielectric fimctions of the SLs. spectra cannot be simulated by a sequence of Ge+Si slabs and compared to those of the compositionally equivalent alloys showed noticeable differences which can be ascribed to a combination of strain and confinement effects. The results agree with experimental findings and theoretical predictions on analogous SLs grown by MBE, thus confirming the reliability of the used technique to produce good quality SLs.