Alkanethiol-Based Single-Molecule Transistors

TL;DR

This study uses first-principles calculations to explore how amino substitution in butanethiol molecules affects their transport properties, revealing enhanced conductance, resonant tunneling, and potential for molecular transistor applications.

Contribution

It demonstrates the impact of amino substitution on transport properties and highlights the potential of amino-substituted butanethiol as a molecular transistor component.

Findings

Amino substitution introduces new states near the Fermi level.

Resonant tunneling causes a sharp increase in current.

Gate voltage can modulate conductance up to 30 times.

Abstract

The transport properties of unsubstituted and amino-substituted butanethiol molecules sandwiched between Au electrodes are investigated by using first-principles approaches. New states are observed around the Fermi levels when -NH2 is substituted for -H in the bridging butanethiol. The amino-substituted states lead to a sharp increase of the current which is credited to the resonant tunneling in the junction. We observe a novel conductance peak at VSD = 0.1 V and negative differential resistance (NDR) in a certain range of source-drain bias. In addition to the I-VSD characteristics, we also investigate the current as a function of gate voltage (I-VG) and find that, for a fixed source-drain bias (VSD = 0.01 V), the gate voltage can modulate the conductance by up to 30 times in the amino-substituted butanethiol junction. These I-VG characteristics suggest that the amino-substituted butanethiol molecular junction may be a promising candidate for field-effect transistors.