Resonant inelastic light scattering in remotely doped wide parabolic GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum wells

We have used resonant inelastic light-scattering spectroscopy in the depolarized backscattering configuration z(y’,x’)z¯ to probe the single-particle excitations of two n-type remotely doped wide parabolic GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum wells, with design curvatures corresponding to empty conduction-band harmonic-oscillator spacings of 4.4 and 3.3 meV. For the former sample, a series of spectra, for excitations near the ${\mathit{E}}_0$+${\mathrm{\Delta }}_0$ gap of the bulk material at the center of the well, reveal two light-scattering peaks with shifts ∼0.85 and ∼3.0 meV, which are strongly resonant with resonance widths of ≲3 meV. Separate resonance curves were extracted, and the two resonance peaks are found to be separated by an energy approximately equal to the scattering peak separation. For the latter sample, similar spectra were obtained which reveal two strongly resonant light-scattering peaks with energy shifts ∼0.65 and ∼2.0 meV, with resonance maxima separated by an energy approximately equal to the scattering peak separation. We have interpreted these results in terms of single-particle transitions between conduction-band subbands and have found them quantitatively consistent with a model for the electron gas in the well distributed as a uniform density slab, giving rise to a square-well-like effective potential, as predicted for this system.