Re-entrant resonant tunneling

TL;DR

This paper investigates how electron-electron interactions influence resonant tunneling through localized states, revealing multiple peaks and co-tunneling effects experimentally in GaAs microstructures.

Contribution

It introduces a simple model showing Coulomb interactions cause multiple resonant peaks and higher-order resonances, supported by experimental observations.

Findings

Electron-electron interactions produce multiple conductance peaks.

Higher-order resonances involve two-electron transitions.

Experimental data shows correlated fluctuations in peak heights.

Abstract

We study the effect of electron-electron interactions on the resonant-tunneling spectroscopy of the localized states in a barrier. Using a simple model of three localized states, we show that, due to the Coulomb interactions, a single state can give rise to two resonant peaks in the conductance as a function of gate voltage, G(Vg). We also demonstrate that an additional higher-order resonance with Vg-position in between these two peaks becomes possibile when interactions are taken into account. The corresponding resonant-tunneling process involves two-electron transitions. We have observed both these effects in GaAs transistor microstructures by studying the time evolution of three adjacent G(Vg) peaks caused by fluctuating occupation of an isolated impurity (modulator). The heights of the two stronger peaks exibit in-phase fluctuations. The phase of fluctuations of the smaller middle peak is opposite. The two stronger peaks have their origin in the same localized state, and the third one corresponds to a co-tunneling process.