Gap separation-controlled nanogap electrodes by molecular ruler electroless gold plating

Abstract

Molecular ruler electroless plated (MoREP) nanogap electrodes: gap separation can be controlled between 2.5 and 3.3 nm by surfactant CnTAB.

Nanogap Electrodes towards Solid State Single‐Molecule Transistors

“…In 2012, Serdioet al reported an improved chemical reaction route and nanogap electrodes with a mean gap size of 3 nm and a 90% yield was demonstrated with a much smoother surface . Although self‐termination can be used to reduce the gap size to a few nanometers, the controllability of this method on the gap size wasn't realizes until 2015, when a new method, termed as molecular ruler electroless gold plating, was reported by Serdio et al In their method, surfactant molecules with different lengths, which physisorbed on the gold electrode surface, were introduced in the reaction process. When the distance between the electrodes becomes so small, after the deposition of Au, that the surfactant molecules on the surface of the two opposite electrodes interdigitate with each other, the plating process will be terminated automatically ( Figure ).…”

“…The growth of the electroless‐plating layer in the nanogap section is self‐terminated by the interdigitation of the surfactant molecules. Reproduced with permission . Copyright 2015, The Royal Society of Chemistry.…”

Direct Deposited Angstrom‐Scale Nanogap Electrodes with Macroscopically Measurable and Material‐Independent Capabilities for Various Applications

“…Despite their importance, fabrication of sub‐5 nm NGEs remains a great technological challenge . Existing NGE‐manufacturing methods can be typically classified into two strategies: physical methods based on planar nanofabrication techniques and chemical methods based on noble metal nanoparticles. Most chemical methods are suitable for creating sub‐1 nm NGEs but limited to a relatively narrow range of applications owing to the contamination induced by linker molecules, the shell‐filled gaps, and/or the restrictions derived from metal nanoparticle size.…”

“…Most chemical methods are suitable for creating sub‐1 nm NGEs but limited to a relatively narrow range of applications owing to the contamination induced by linker molecules, the shell‐filled gaps, and/or the restrictions derived from metal nanoparticle size. Physical methods, including direct patterning techniques, breaking‐/cracking‐based methods, and controllable deposition, are fundamentally limited by the basic planar nanofabrication techniques. Particularly, direct patterning techniques variously suffer from high equipment costs, low throughput, and poor scalability to large sizes.…”

“…Though breaking‐based methods can be used to produce sub‐1 nm NGEs, the intrinsic obstacles mentioned above result in discrete and material‐limited NGEs with the fractal facing electrode surface blocking the realization of large‐scale complex systems. Controllable deposition is relatively simple for large‐scale fabrication, while the formed NGEs typically face limitations derived from large gap width, problematic rough surfaces, the solution environment, or/and contaminations from the shadow‐mask fabrication process. However, simply continuing to improve existing NGE‐fabricating methods is insufficient since each method has its own serious inherent defects.…”