Hot-phonon effects on electron transport in quantum wires

Hot (nonequilibrium) phonon effects on electron transport in rectangular GaAs/AlAs quantum wires have been investigated by a self-consistent Monte Carlo simulation. Confinement and localization of optical phonons have been taken into account. We have demonstrated that at room temperature hot optical phonons lead to a significant increase in electron drift velocity. This hot-phonon drag effect is due to the strongly asymmetric nonequilibrium phonon distribution. As a result, phonon absorption for forward transitions (electron gains momentum along electric field) is enhanced, whereas absorption for backward transitions (electron gains momentum against electric field) is suppressed. At low temperatures diffusive heating of electrons by hot phonons dominates over hot-phonon drag and the electron drift velocity decreases.