The dispersion of the plasma frequency of layered electron gases in GaAs-(AlGa) As heterostructures was determined by inelastic light scattering. The measured dispersions differ from that in two- and three-dimensional plasmas. They are linear in the in-plane component of the wave vector. This observation confirms predictions of theoretical models.

• Received 30 April 1982

DOI:https://doi.org/10.1103/PhysRevB.25.7867