We show that mismatch of the piezoelectric parameters between layers of multiple-quantum well structures leads to modification of the electron-phonon interaction. In particular, short-wavelength phonons propagating perpendicular to the layers with wavevector close to 2πn/d, where d is the period of the structure, induce a strong smoothly-varying component of the piezo-potential. As a result, they interact efficiently with 2D electrons. It is shown, that this property leads to emission of collimated quasi-monochromatic beams of high-frequency acoustic phonons from hot electrons in multiple-quantum well structures. We argue that this effect is responsible for the recently reported monochromatic transverse phonon emission from optically excited GaAs/AlAs superlattices, and provide additional experimental evidences of this.
@article{arxiv.cond-mat/0606266,
title = {Resonance-like piezoelectric electron-phonon interaction in layered structures},
author = {B. A. Glavin and V. A. Kochelap and T. L. Linnik and A. J. Kent and N. M. Stanton and M. Henini},
journal= {arXiv preprint arXiv:cond-mat/0606266},
year = {2009}
}