Light Scattering by Photoexcited Two-Dimensional Electron Plasma in GaAs-(AlGa) As Heterostructures

We report resonant inelastic light scattering by photoexcited electrons in GaAs-(AlGa)As multiple quantum-well heterostructures and find that a variable-density two-dimensional electron-hole plasma is created in a controlled manner. The energy levels and collective electron-electron and electron-phonon interactions were studied for carrier densities as high as ∼3×${10}^{12}$ ${\mathrm{cm}}^{-2\mathrm{}}$. Charge neutrality is preserved in each quantum well. Complex collective interactions occur among modes involving transitions between quantum-well states.