Exciton effects in stress-induced doubly resonant Raman scattering: GaAs

We have calculated the Raman tensor components, including exciton effects, in the case of stress-induced doubly resonant Raman scattering via deformation-potential interaction in GaAs. Our results are in agreement with experiments as a function of stress and incident photon energy. From the fit we obtain the lifetime broadening of the heavy- and light-hole excitons, (3/2)=3.7 meV and (1/2)=1.5 meV, respectively. The evolution of the resonance upon application of uniaxial stress towards the double resonance is shown. It is also demonstrated that near resonance the discrete exciton states give a dominant contribution and that the replacement of the continuous excitonic contribution with uncorrelated electron-hole pairs changes only slightly the value of the total Raman tensor component near resonance.