Magneto infrared absorption and polaron coupling in high electron density GaAs quantum well

We investigated the cyclotron resonance (CR) on a series of samples containing high-density 2DEG (7.4-12 x 10(11) cm(-2)) in GaAs/AlAs single quantum wells (in high magnetic fields up to 28 T) in order to study the resonant polaron coupling. We did not observe any anomalies of the CR peak's evolution around the longitudinal optical (LO) phonon energy of GaAs (homega(LO) = 36.3 meV). Instead, a pinning of the CR peak occurs near the transverse optical (TO) phonon energy and is accompanied by an increase of the width and of the intensity of the peak. We have simulated the transmission of the whole structure using a multilayer dielectric model, which allows us to determine the correct values of the relaxation frequency and its variation with magnetic field. We discuss the different possibilities of the coupling observed around the TO energy. (C) 2002 Elsevier Science B.V. All rights reserved