Hot phonons in quantum wires

Abstract

We present results of Monte Carlo simulations of electron relaxation dynamics in rectangular GaAs quantum wires (QWIS) embedded in AlAs. Electron interactions with confined LO phonons, interface optical phonons, bulk-like acoustic phonons as well as non-equilibrium (hot) optical phonons have been taken into account. It has been found that hot phonons come into play at electron concentrations exceeding 105 cm-1. In QWIS electrons having appreciably different initial energies generate non-equilibrium phonons at different q-space regions which do not overlap. In turn, these phonons can be reabsorbed only by the electrons that have generated them. Consequently, hot-phonon effects become weaker as the energy distribution of excited electrons broadens. This result is in complete contrast to the case of bulk materials and quantum wells where the injected electron energy distribution virtually does not affect non-equilibrium phonon build-up and the reabsorption rate.