Second-order Raman scattering in InSb

The second-order Raman spectra of InSb are investigated at room temperature and 77 K. Measurements were performed for several polarizations of the incident and scattered light in order to separate the three independent components of the Raman tensor. In the region of 2TA only ${\Gamma }_1$ scattering was observed, while other overtone and combinations processes were seen for ${\Gamma }_1$ and ${\Gamma }_{15}$ symmetry. No ${\Gamma }_{12}$ scattering was observed. The positions of the second-order Raman bands are compared to existing neutron scattering and infrared absorption data. The dependence of the scattering cross section on the exciting laser frequency was measured qualitatively in the region around the $E_1+{\Delta }_1$ gap for several second-order bands: $2\mathrm{TA}\left({\Gamma }_1\right)$, $2\mathrm{TO}\left({\Gamma }_1\right)$, $2\mathrm{TO}\left({\Gamma }_{15}\right)$, and $2\mathrm{LO}\left({\Gamma }_1\right)$. At the $E_1$ gap only the resonance behavior of the $2\mathrm{LO}\left({\Gamma }_1\right)$ could be studied. Values for several electron-two-phonon deformation potentials are estimated.