Propagation of plasmons across layers of GaAs-Ga1−xAlxAs superlattices

The transformation from quasi-two-dimensional to three-dimensional behavior of the free-electron gas in GaAs-Ga1−xAlxAs multiple quantum well structures was observed. This transformation corresponds to the establishment of well defined three-dimensional plasmon modes measured by Raman scattering, which propagate across layers of an n-type doped superlattice when the layer thicknesses are reduced to 20 Å or less. This type of behavior is consistent with the Kronig–Penney type model describing coupling between the wells and formation of energy minibands in a superlattice.