Electron-interface phonon scattering in asymmetric semiconductor quantum well structures

Abstract

Electron-interface phonon scattering rates in asymmetric single quantum well and step quantum well structures are calculated by means of the interaction Fröhlich-like Hamiltonian between an electron and interface optical phonons in a four-layer heterostructure given recently. The intrasubband and intersubband electron scattering rates are given as functions of quantum well width, step width and step height. We have found that the electron scattering depends strongly on the potential parameters and the usual selection rules for these transitions are broken down in asymmetric heterostructures; the interface LO modes are more important than the interface TO modes for the electron-interface phonons scattering in heterostructures; the intrasubband scattering rates are insensitive functions of step width and step height, and the intersubband scattering rates are complicated functions of step height and step width in step quantum wells. Moreover, we have also observed that the scattering rates for intrasubband and intersubband transitions have no obvious changes in the case that the first or second subband energy level crosses the step height in a step quantum well.