Electron–phonon interaction in a doped GaAs quantum well

We investigate the cyclotron resonance (CR) on a single GaAs quantum well containing a two-dimensional electron gas View the MathML source, in magnetic fields up to View the MathML source in order to study the resonant polaron coupling. When the normal to the surface of the sample is in the same direction as that of light propagation, we do not observe an anomaly of the CR absorption in the optical phonon range of energy. When the normal of the sample is tilted with respect to the light propagation direction (and with the magnetic field direction) we observe a pinning of the CR peak at an energy lower than that of the longitudinal optical (LO) phonon energy. This mode is identified as the coupled intersubband plasmon–LO phonon of the quantum well.