Condensed Matter Seminar Series

Quantum Drift-Diffusion Equations for Semiconductor Superlattices

Luis Bonilla

University Caros III, Madrid

Thursday April 12,  11:30 am,  Room 298,  Physics Building

Abstract:  We present quantum kinetic equations for electron transport in quasi one-dimensional periodic structures (superlattices) having one or two populated minibands. Electron-electron collisions are modeled by the Poisson equation and inelastic collisions by a BGK-type term that describes relaxation to local equilibrium. We derive drift-diffusion equations and systems in the hyperbolic limit in which electron-electron and inelastic collisions are equally important and dominate other terms in the kinetic equations. Numerical simulation of the drift-diffusion equations show high-frequency self-sustained oscillations of the current through a dc voltage biased superlattice, which are similar to the experimentally observed behavior.