Resonance Raman scattering in semiconductors under uniaxial stress:E1(E1+Δ1)gaps

Abstract

The effect of a [111] stress on the resonances of the Raman scattering by LO and TO phonons in InSb and Ge near the $E_1$ gaps was investigated. Large effects of the stress on the resonance Raman efficiencies were observed: the TO scattering is stress enhanced for certain polarization configurations, while the forbidden LO scattering in InSb is decreased. The enhancement of the TO scattering is related to the twoband deformation potential terms in the resonant scattering efficiency. A strong cancellation occurs in unstressed material between the contributions of the [111] and the $〈\overline{1}11〉$ $E_1$ gaps which is lifted by the [111] stress. The forbidden scattering is decreased by the stress as a result of the splitting of the [111]-$〈\overline{1}11〉$ gaps. Calculations of the resonance effects and their stress dependence reproduce well the observed behavior.