Energy and momentum relaxation rates for confined and interface modes in quantum well structures

Abstract

In GaAs/AlAs quantum well structures both the confined GaAs optic phonon and the AlAs interface polariton (IP) mode contribute to the energy and momentum relaxation of hot electrons. It has been shown that in real multiple quantum well structures elastic scattering of phonons can lead to a non-drifting population of hot phonons, which results in a suppression of the high-field electron drift velocity. The consequences for device application are obvious. The non-drift of the mode is determined by the relative magnitudes of its energy and momentum relaxation rates. We present a calculation of the lifetime and the elastic scattering rates for confined and interface modes in GaAs/AlAs quantum wells. It is found that the decay rates of the two modes exhibit different well-width dependences, and that scattering from interface roughness is the dominant mechanism for momentum relaxation. The implications for high-field transport are discussed.