Tunneling of Electrons and Holes in Asymmetric Double Quantum Wells

Abstract

The quantum mechanical phenomenon of tunneling is of interest from fundamental as well as device points of views. Semiconductor microstructures, and in particular asymmetric double quantum well structures (a-DQWS), provide ideal systems for investigating tunneling phenomena, especially when an electric field is applied to bring various electronic levels into resonance. We first discuss various resonant and nonresonant tunneling processes for electrons and holes, including both coherent and incoherent resonant tunneling and then review recent extensive investigations of resonant and non-resonant tunneling rates of electrons and holes in asymmetric double quantum well structures using time resolved spectroscopy. We also show that cw and ultrashort pulse experiments probe different physics and that it is difficult to obtain quantitative information about resonances and resonant tunneling rates from cw experiments.