Coherent resonant tunneling in ac fields

TL;DR

This paper investigates how external electromagnetic fields influence resonant tunneling in heterostructures, comparing models with localized AC voltages and homogeneous photon irradiation, revealing distinct tunneling mechanisms and transmission features.

Contribution

It introduces a transfer Hamiltonian approach to analyze coherent resonant tunneling under different electromagnetic field models, highlighting the differences in tunneling mechanisms.

Findings

Different tunneling mechanisms in localized vs. homogeneous fields

Distinct features in transmission and current density

General expression for transition probability using Green's functions

Abstract

We have analyzed the tunneling transmission probability and electronic current density through resonant heterostructures in the presence of an external electromagnetic field. In this work, we compare two different models for a double barrier : In the first case the effect of the external field is taken into account by spatially dependent AC voltages and in the second one the electromagnetic field is described in terms of a photon field that irradiates homogeneously the whole sample. While in the first description the tunneling takes place mainly through photo sidebands in the case of homogeneous illumination the main effective tunneling channels correspond to the coupling between different electronic states due to photon absorption and emission. The difference of tunneling mechanisms between these configurations is strongly reflected in the transmission and current density which present very different features in both cases. In order to analyze these effects we have obtained, within the Transfer Hamiltonian framework, a general expression for the transition probability for coherent resonant tunneling in terms of the Green's function of the system.