Resonant Raman scattering of electrons in quantum wells: Identification of elementary excitations

Inelastic scattering of light by electrons in a quantum well was studied. We considered the resonant Raman scattering associated with intersubband electronic excitations. Evidence is provided that when the two lowest subbands are considered four types of excitations are present. They give rise to two scattering lines associated with single-particle excitations and another two associated with collective charge-density excitations, while spin-density excitations are not considered. The shape of the Raman spectrum strongly depends on several characteristics in the experiment, namely, the quantum well width, the concentration of the carriers, many-body effects, the temperature, and, mainly, the momentum-transfer dependent on the laser-photon frequency and the experimental geometry. Particular experimental results are satisfactorily described.