RAMAN SCATTERING INTENSITIES OF FOLDED LONGITUDINAL ACOUSTIC PHONONS IN GexSi1-x/Si SUPERLATTICES

In terms of photoelastic mechanism we have investigated the Raman scattering intensities of the folded longitudinal acoustic (FLA) phonons in Ge_xSi_1-x/ Si superlattices (SLs), taking into account the differences between the acoustic and photoelastic parameters of the two constituents in the SLs. The relative intensities calculated for the FLA phonons are in excellent agreement with the experimental results at the frequencies up to about 50 cm^-1. The broadening of the linewidth arising from the so called strong acoustic attenuation, which was reported previously located around the frequency 15 cm^-1 in Ge_xSi_1-x/Si SLs(x≈0.5), has not been observed in this work.