# Electromigrated nanoscale gaps for surface-enhanced Raman spectroscopy

## TL;DR

This paper introduces a scalable nanogap substrate for surface-enhanced Raman spectroscopy that achieves high sensitivity suitable for single-molecule detection through electromigrated gaps and plasmonic focusing.

## Contribution

The authors develop a simple, scalable nanogap substrate with electromigrated gaps that significantly improve SERS sensitivity for single-molecule detection.

## Key findings

- Nanogap substrates exhibit hallmarks of high Raman sensitivity.
- Electrodynamic simulations show plasmonic focusing in the nanogaps.
- Enhancements approach single-molecule SERS levels.

## Abstract

Single-molecule detection with chemical specificity is a powerful and much desired tool for biology, chemistry, physics, and sensing technologies. Surface-enhanced spectroscopies enable single molecule studies, yet reliable substrates of adequate sensitivity are in short supply. We present a simple, scaleable substrate for surface-enhanced Raman spectroscopy (SERS) incorporating nanometer-scale electromigrated gaps between extended electrodes. Molecules in the nanogap active regions exhibit hallmarks of very high Raman sensitivity, including blinking and spectral diffusion. Electrodynamic simulations show plasmonic focusing, giving electromagnetic enhancements approaching those needed for single-molecule SERS.