Abstract

Electronic energy relaxation in quantum dots is studied theoretically in polar semiconductor materials, with the emphasis put on the phonon-bottleneck problem and the electron-LO-phonon coupling. The theory is based on multiphonon states of the electron-phonon system and the self-consistent Tamm-Dancoff approximation is used for the electronic self-energy. For several materials (GaAs, InAS and InP) the electronic relaxation rate is shown numerically to be on the scale from hundreds of fs to tens of ps, for electron energy-level separations in the broad range from about one LO-phonon energy to about three or four optical-phonon energies (small quantum dots). This quantitative result is in a rather good agreement with experimental data. The electronic relaxation rate does not appear to be crucially dependent on the quantum dot size, although it displays some resonance features at such values of the electronic energy-level separations, which are a multiple of the optical-phonon energy. A preliminary report is in ref. [1].

© 1998 IEEE