Effect of Quantum Confinement on Electron Tunneling through a Quantum Dot

TL;DR

This paper investigates how quantum confinement affects electron tunneling in quantum dots, revealing that inelastic cotunneling is suppressed and conductance is dominated by elastic cotunneling or resonant tunneling depending on temperature.

Contribution

It provides a theoretical analysis of tunneling processes in quantum dots considering Coulomb blockade and quantum confinement effects simultaneously.

Findings

Inelastic cotunneling is suppressed in the quantum confinement limit.

Conductance near minima is governed by elastic cotunneling at low temperature.

Resonant tunneling dominates at high temperature.

Abstract

Employing the Anderson impurity model, we study tunneling properties through an ideal quantum dot near the conductance minima. Considering the Coulomb blockade and the quantum confinement on an equal footing, we have obtained current contributions from various types of tunneling processes; inelastic cotunneling, elastic cotunneling, and resonant tunneling of thermally activated electrons. We have found that the inelastic cotunneling is suppressed in the quantum confinement limit, and thus the conductance near its minima is determined by the elastic cotunneling at low temperature ($k_BT \ll \Gamma$, $\Gamma$: dot-reservoir coupling constant), or by the resonant tunneling of single electrons at high temperature ($k_BT \gg \Gamma$).