Programmable definition of nanogap electronic devices using self-inhibited reagent depletion

Abstract

Electrodes exhibiting controlled nanoscale separations are required in devices for light detection, semiconductor electronics and medical diagnostics. Here we use low-cost lithography to define micron-separated electrodes, which we downscale to create three-dimensional electrodes separated by nanoscale gaps. Only by devising a new strategy, which we term electrochemical self-inhibited reagent depletion, were we able to produce a robust self-limiting nanogap manufacturing technology. We investigate the method using experiment and simulation and find that, when electrodeposition is carried out using micron-spaced electrodes simultaneously poised at the same potential, these exhibit self-inhibited reagent depletion, leading to defined and robust nanogaps. Particularly remarkable is the formation of fractal electrodes that exhibit interpenetrating jagged elements that consistently avoid electrical contact. We showcase the new technology by fabricating photodetectors with responsivities (A/W) that are one hundred times higher than previously reported photodetectors operating at the same low (1–3 V) voltages. The new strategy adds to the nanofabrication toolkit method that unites top–down template definition with bottom–up three-dimensional nanoscale features.

Large-area plastic nanogap electronics enabled by adhesion lithography

“…An electrochemical approach was introduced by Lam et al, which utilises electroplating (via a so-called self-inhibited reagent depletion method) to narrow down macroscale gaps (originally fabricated with conventional low-cost techniques) to the nanoscale. 60 The authors demonstrated high-responsivity lead sulphide (PbS) quantum dot (QD)-based photodetectors based on these nanogaps. There were, however, some uniformity issues, while only symmetric electrode structures can be formed by this method.…”

Real-time tracking of metal nucleation via local perturbation of hydration layers

“…Electrochemical deposition offers the most versatile and scalable route for material growth, spanning from atomic-scale control of sophisticated architectures to large-scale industrial processes (e.g. electrowinning) 1 – 7 . The mechanism of nucleation and growth of metallic phases has been mostly studied employing electrochemical transient measurements, for which various models have been developed linking the time-dependent current to microscopic parameters such as nucleation rate and nuclei density 8 , 9 .…”

Highly stable, extremely high-temperature, nonvolatile memory based on resistance switching in polycrystalline Pt nanogaps

“…Various techniques employing mechanically controlled break junctions (MCBJs) 19 20 21 , electron-beam lithography 22 , chemical etching 23 24 , and other methods have been developed to fabricate nanogap electrodes 25 26 27 28 . In this study, we used a Pt nanogap, which has a melting temperature higher than that of the Au nanogaps that are commonly used for NGS 29 .…”