Resonant Raman scattering by plasmons and LO phonons near the E1 and E1+Δ1 gaps of GaSb

Abstract

We report on the resonance of Raman scattering by plasmons near the $E_1$ and $E_1$+${\Delta }_1$ gaps of heavily doped n-type GaSb. The dipole-allowed Raman scattering by plasmons due to the electro-optic (Fröhlich interband) coupling of bands interferes with the dipole-forbidden q-dependent Fröhlich intraband scattering. Absolute values of Raman polarizabilities and efficiencies are displayed. The interference is compared with that of the LO phonons seen from the surface depletion layer. Theoretical expression for the resonance of the different scattering mechanisms (electro-optic, Fröhlich intraband, electric field induced, deformation potential, impurity induced, 2LO) near the $E_1$ and $E_1$+${\Delta }_1$ gaps are derived and compared with the experiment. The dispersion of the second-order susceptibility ${\mathrm{\chi }}_{123}^{\mathrm{}\left(2\right)\mathrm{}}$(ω${,}_{\mathit{L}}$,-${\mathrm{\Omega }}_{\mathit{P}}$,${\mathrm{\omega }}_{\mathit{S}}$0 is displayed and the Faust-Henry coefficient of GaSb determined.