We apply Raman spectroscopy to study the phonon spectrum in periodical GeSiSn/Si nanostructures with Sn concentration varied from 0 to 20%. In the optical spectral region, an insignificant shift of the phonon mode positions with a variation of the Sn content prevents determination of Sn concentration relying only on the optical phonons behavior. In the acoustic region, we observe the doublets of the folded acoustic phonons, the spectral positions of which undergo the low-frequency shift with increasing the Sn content. The application of the elastic continuum model with the linear approximation of sound velocity via Sn content in GeSiSn layers fails to explain the experimental results. This indicates a nonlinear Sn concentration dependence of sound velocity in GeSiSn layers which describes well the positions of the folded acoustic phonons.
|Number of pages||7|
|Journal||Journal of Physics: Conference Series|
|Publication status||Published - 1 Mar 2020|
|Event||4th International Conference on Metamaterials and Nanophotonics, METANANO 2019 - St. Petersburg, Russian Federation|
Duration: 15 Jul 2019 → 19 Jul 2019