We measured resonant Raman scattering by intersubband electronic excitations
in GaAs/AlAs single quantum wells (QWs) with well widths ranging from 8.5 to 18
nm. In narrow (less than 10 nm) QWs with sufficiently high electron
concentrations, only single-particle excitations (SPEs) were observed in
intersubband Raman scattering, which was confirmed by the well-width dependence
of Raman spectra. We found characteristic variations in Raman shift and line
shape for SPEs with incident photon energy in the narrow QWs.Comment: 5 pages including 4 figure