Many Body Effects on the Cyclotron Resonance in Electron Inversion Layers

At low temperatures, the electrons in the inversion layer of a silicon metal-oxide-semiconductor field-effect-transistor or a GaAs/AlGaAs heterojunction behave dynamically as a two dimensional electron gas.1 This leads to interesting correlation effects for a number of reasons. The reduced dimensionality typically enhances the importance of potential or interaction energies relative to the kinetic energy. Also, it is possible to vary the two-dimensional density of electrons and, hence, to vary the relative strength of the Coulomb potential. Finally, in the best devices, the scattering due to impurities is very small and can, in fact, be weaker than electron-electron scattering, making it possible to observe correlation effects experimentally. The presence of a strong perpendicular magnetic field can further enhance correlation effects because of the Landau quantization of the kinetic energy. For example, at low densities and strong magnetic fields, correlation effects give rise to the fractional quantum Hall effect.2,3