Batch fabrication of gold-gold nanogaps by E-beam lithography and electrochemical deposition
We report on the successful development of a well-controlled two-step batch nano-fabrication process to achieve nanometer-size gaps at the wafer scale. The technique is based on an optimized electron-beam lithography process, which enables the fabrication of nanogaps in the range (15 +/- 4) nm. Following this first step, the feedback-controlled electrochemical deposition of gold from an aqueous HAuCl4-based electrolyte is applied to further reduce the size of the gap down to about 0.3-1.0 nm. This protocol was successfully demonstrated by fabricating more than 385 nanogaps on a 4 inch wafer. The reproducible fabrication of nanogaps in the range between 0.3 and 1.0 nm opens up new perspectives for addressing the electrical and reactivity properties of single molecules and clusters in confined space under well-controlled conditions.