Electron-phonon interaction effects in a quasi-two-dimensional electron gas in the GaAs-Ga1−xAlxAs heterostructure

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Abstract
From a single-electron theory it is well established that the polaron effective mass in purely two-dimensional systems is larger than that in the corresponding three-dimensional case. On the other hand, recent cyclotron-resonance experiments have shown that the polaronic mass in two-dimensional GaAs heterostructures is a factor of 3 smaller than the three-dimensional results. In order to understand the discrepancy between the experiments and this simple theory we have improved the model by taking into account the electron interaction with both interface and longitudinal bulk phonons. We have also included in the calculation the effects of the electron screening within the random-phase-approximation formalism and the electron subband wave function. In contrast to previous works we have shown that the interface phonons give a significant contribution to the polaronic energy and effective mass and obviously cannot be neglected. The results of our calculations for the polaron mass correction are in excellent agreement with the experiment measurements.