Composition- and Temperature-Resolved Raman Shift of Silicon

Abstract

We formulated the composition and temperature dependence of the Si and Si1– xGe x Raman shift from the perspectives of bond order–length–strength correlation and local bond average approach. It is verified that the Raman shift Δω varies in the form of Δω ∝ zE1/2/ d, with inclusion of bond length d and energy E changing with temperature and composition. Numerical reproduction of the thermally induced Si1– xGe x phonon softening indicates that bond thermal expansion and energy loss dictate the frequency redshift, which resulted in quantitative information on the bond energy and the reference frequencies from which the Raman shifts proceed. Observations not only gain deeper insight into the mechanism of the Raman shift but also demonstrate the revealing power of Raman technique for the bonding thermodynamics.