Tunneling current spectroscopy of a nanostructure junction involving multiple energy levels

TL;DR

This paper models tunneling current in nanostructure junctions with multiple energy levels using a multi-level Anderson model and nonequilibrium Green's functions, revealing complex spectra and negative differential conductance effects.

Contribution

It introduces a comprehensive theoretical framework for analyzing tunneling in multi-level nanostructures, including Coulomb interactions and spectral functions.

Findings

Negative differential conductance observed in quantum dot junctions

Spectral function derived in closed form for complex systems

Tunneling spectra analyzed for shell-tunneling and shell-filling cases

Abstract

A multi-level Anderson model is employed to simulate the system of a nanostructure tunnel junction with any number of one-particle energy levels. The tunneling current, including both shell-tunneling and shell-filling cases, is theoretically investigated via the nonequilibrium Green's function method. We obtain a closed form for the spectral function, which is used to analyze the complicated tunneling current spectra of a quantum dot or molecule embedded in a double-barrier junction. We also show that negative differential conductance can be observed in a quantum dot tunnel junction when the Coulomb interactions with neighboring quantum dots are taken into account.