Resonant Electronic Raman Scattering in Semiconductors

Electronic Raman scattering on shallow donors in semiconductors is enormously enhanced when the incident photon energy approaches the fundamental exciton region. This excitonic resonance was observed for the first time and it was found that ${\sigma }_{\mathrm{peak}}\approx 5\times {10}^{-14\mathrm{}}$ ${\mathrm{cm}}^2$ for CdTe and GaAs in the $n=2\mathrm{}$ free-exciton resonance. The enhancement of ≳ ${10}^{10}$ over off-resonance excitation and the peculiar $n=2\mathrm{}$ exciton predominance are well described in a model of exciton-polariton-mediated light scattering.