Theory of Raman spectra of heavily doped semiconductor multiple quantum wells

We present theoretical studies of the Raman spectra of heavily doped GaAs-AlxGa1-xAs multiple quantum wells in an attempt to understand the effects of heavy two-dimensional (2D) doping on the electronic structures and optical properties of semiconductors. Samples of GaAs-AlxGa1-xAs multiple quantum wells with x=0.2 and 0.4, well-barrier widths around 100 A, and 2D electron densities up to more than 1x1013 cm-2 are examined. Intersubband and intrasubband Raman plasmon modes are calculated with an energy-dependent effective-mass theory, which takes into account the band nonparabolicity. The screened external potential due to impurity and electron charge distribution including the exchange and correlation effects are calculated self-consistently within the local-density approximation. The resulting Raman spectra are found to be sensitive to the shape of the screened potential, and they are in qualitative agreement with experimental data. copyright 1996 The American Physical Society