Spatially resolved Raman scattering from hot acoustic and optic plasmons

A two-dimensional electron gas drifting under a lateral bias is also heated, and the drift and heating have dramatic effects on its collective plasmon modes. A low-energy feature is observed in polarized Raman scattering in addition to the usual intrasubband plasmon mode, and disperses linearly with in-plane wave vector. Large variations in the Raman intensities and energies of the intrasubband plasmon and the tow-energy feature are observed with position along the drift channel, together with variations in the electron temperature and in the integrated photoluminescence intensity. These effects are discussed in terms of a simple model involving a second sheet of electrons near the current injection contact; the low-energy mode is ascribed to an additional acoustic plasmon mode arising from this double-electron sheet geometry.