QUANTUM KINETIC-STUDY OF THE ELECTRON-LO-PHONON INTERACTION IN A SEMICONDUCTOR

We present a full quantum-mechanical study of the early time kinetics of a coupled electron-LO-phonon system in a semiconductor quantum wire . Schrodinger's equation is directly solved to obtain the many-body wa ve function for a conduction electron interacting with the complete sp ectrum of phonon modes. This approach has the advantage of treating th e electron and the phonons as well as their correlation on equal footi ng and as interdependent entities. We show that the electron and phono n observables illustrate the non-Markovian nature of the early time ki netics, namely, a retarded loss of the electron's momentum and an init ial overshoot in it's kinetic energy. These effects are shown to stem from the buildup of correlation between the electron and the phonons a nd are mediated by virtual transitions. It is shown further that the c ontinuous nature of the electron-phonon interaction has important cons equences in both the electron's relaxation and transport behavior, e.g ., the suppression of scattering in strong longitudinal electric field s. The quantum kinetic results are compared to those obtained from a t raditional semiclassical treatment.