Abstract
We present a combined Raman spectroscopy and density functional perturbation theory (DFPT) study of phonon variation with composition in the mixed crystals SnSSe. The experimentally observed two-mode behavior of the and vibrations involving Se(S) atoms is shown to arise from the lack of overlapping of the corresponding phonon dispersion bands in SnS and SnSe. This offers a unique opportunity to assess local distortions of the trigonal SnSe pyramids in SnSSe as no Se and S mode mixing is involved. The dependence of local height and base length of SnSe pyramids with is derived by a procedure that uses the measured (Se) and (Se) phonons in SnSSe, those calculated by DFPT for SnSe at different hydrostatic pressure, DFPT phonon dispersion, and the contribution from mass-disorder induced phonon self-energy.
- Received 4 February 2013
DOI:https://doi.org/10.1103/PhysRevB.87.104302
©2013 American Physical Society