Unprecedented efficient electron transport across Au nanoparticles with up to 25-nm insulating SiO2-shells

Chuanping Li,Chen Xu,Yongdong Jin,David Cahen

doi:10.1038/s41598-019-54835-2

Abstract

Quantum tunneling is the basis of molecular electronics, but often its electron transport range is too short to overcome technical defects caused by downscaling of electronic devices, which limits the development of molecular-/nano-electronics. Marrying electronics with plasmonics may well present a revolutionary way to meet this challenge as it can manipulate electron flow with plasmonics at the nanoscale. Here we report on unusually efficient temperature-independent electron transport, with some photoconductivity, across a new type of junction with active plasmonics. The junction is made by assembly of SiO2 shell-insulated Au nanoparticles (Au@SiO2 NPs) into dense nanomembranes of a few Au@SiO2 layers thick and transport is measured across these membranes. We propose that the mechanism is plasmon-enabled transport, possibly tunneling (as it is temperature-independent). Unprecedentedly ultra-long-range transport across one, up to even three layers of Au@SiO2 in the junction, with a cumulative insulating (silica) gap up to 29 nm/NP layer was achieved, well beyond the measurable limit for normal quantum mechanical tunneling across insulators (~2.5 nm at 0.5–1 V). This finding opens up a new interdisciplinary field of exploration in nanoelectronics with wide potential impact on such areas as electronic information transfer.

Highlights

Quantum tunneling is the basis of molecular electronics, but often its electron transport range is too short to overcome technical defects caused by downscaling of electronic devices, which limits the development of molecular-/nano-electronics
The nanomembrane is made of close-packed Au@SiO2 core-shell NPs with controllable and homogenous silica thickness ranging from ~5.0 ± 1.1 nm to 14.5 ± 1.7 nm, i.e., a total SiO2 thickness from 10–29 nm (Supplementary Fig. S1)
3 mL colloidal Au@SiO2 NPs with silica shell of varied thickness were prepared[22] and poured into a plastic container; 470 μL hexane was added to the solution to form a liquid/liquid interface, and 3.7 mL methanol was poured into the mixture rapidly to capture the NPs at the hexane/water interface

Summary

Introduction

Quantum tunneling is the basis of molecular electronics, but often its electron transport range is too short to overcome technical defects caused by downscaling of electronic devices, which limits the development of molecular-/nano-electronics. S2 and S4), due to electromagnetic coupling between the NPs. Figure 2d,e and Supplementary Fig. S5 show typical scanning electron microscope (SEM) top-/ side-view images of the nanomembrane and the resulting sandwich-type meta-junction (with top Au pad electrode).

Results

Conclusion