Femtosecond to picosecond electron-energy relaxation and Froehlich coupling in quantum dots

Abstract

Electron relaxation in quantum dots is studied theoretically in polar semiconductor materials, with an emphasis put on the phonon-bottleneck problem and electron-LO-phonon coupling. The theory is based on multiphonon states of the electron-LO-phonon system and the self-consistent Tamm-Dancoff approximation is used for the electronic self-energy. Electronic relaxation rate is shown numerically to be on the scale from hundreds fs to tens ps, for electron energy-level separations being in the broad range from about one LO-phonon energy to about three or four optical-phonon energies. Despite of displaying some resonance features, the electronic relaxation rate does not appear to be crucially dependent on the quantum dot size.