Phonon Scattering and Relaxation Properties of Lower Dimensional Electron Gases

Abstract

We systematically compare the electron-phonon scattering times of zero-, one-, and two-dimensional semiconductor systems. They depend strongly on the dimensionality, the confinement width(s) and the energy of the electron. The energy loss rates of heated electron gases due to emission and absorption of both LA and LO phonons are calculated for various lattice temperatures. In the lattice matched In0.53Ga0.47As-InP system for instance, the carrier cooling is dominated by LO phonon scattering for an electron temperature Te above 30K and by the interaction with LA phonons for Te below 25K. In the latter case, the energy relaxation of the one-dimensional electron gas can be faster or slower than that of the corresponding two-dimensional system depending on the electron density. The LA phonon scattering in 0D systems becomes increasingly quenched with increasing confinement energy. This intrinsic effect should strongly affect the luminescence efficiency of quantum dots.