Interference-based molecular transistors.

Ying Li,Jan A Mol,Simon C Benjamin,G Andrew D Briggs

doi:10.1038/srep33686

Abstract

Molecular transistors have the potential for switching with lower gate voltages than conventional field-effect transistors. We have calculated the performance of a single-molecule device in which there is interference between electron transport through the highest occupied molecular orbital and the lowest unoccupied molecular orbital of a single molecule. Quantum interference results in a subthreshold slope that is independent of temperature. For realistic parameters the change in gate potential required for a change in source-drain current of two decades is 20 mV, which is a factor of six smaller than the theoretical limit for a metal-oxide-semiconductor field-effect transistor.

Highlights

Molecular transistors have the potential for switching with lower gate voltages than conventional fieldeffect transistors
The transmission peak is still in the distribution window but the height is suppressed. Both mechanisms influence the current as a function of the gate voltage
If the first mechanism dominates, the gate voltage for switching on and off the current is limited by the electron temperature, i.e. the change of the gate voltage (×e) must be larger than the width of the Fermi-Dirac distribution function of the leads

Summary

Introduction

Molecular transistors have the potential for switching with lower gate voltages than conventional fieldeffect transistors. Vg required to change the source-drain current by a factor of ten This is limited by the exponential tail in the Fermi-Dirac distribution of the thermally excited electrons passing over the barrier created by the gate, which in the best case gives a current ∝e−eVg/kBT1, i.e. a subthreshold swing of 60 mV/decade. This thermal limitation can be overcome by exploring quantum effects, as is done in tunnel-field effect transistors[2,3]. We provide a theoretical study, with a calculation for specific parameters, to show how quantum interference effects in single-molecule devices[4,5,6,7,8,9,10] could be used to give vast improvements in the subthreshold swing, and in the energy consumption of logic circuits

Methods

Results

Conclusion