Resonant Raman scattering by LO phonons near theE0+Δ0gap of GaSb

Abstract

We report on the resonance of Raman scattering by LO phonons near the $E_0$+${\Delta }_0$ gap of GaSb. Whereas the dipole-forbidden Fröhlich-induced scattering by LO phonons as well as the two-LO-phonon scattering are only seen at resonance, the weakly resonant dipole-allowed deformation potential-induced scattering by LO phonons dominates near the $E_0$+${\Delta }_0$ gap. The dipole-forbidden contribution is, however, clearly observed by means of its interference with the dipole-allowed scattering in the appropriate configurations. Absolute values for the Raman polarizabilities and efficiencies are displayed. A theoretical analysis yields the position of the $E_0$+${\Delta }_0$ gap and its Lorentzian broadening at 100 K, 1.549±0.007 eV, and 6±2 meV, respectively.