Uniform patterning of sub-50-nm-scale Au nanostructures on insulating solid substrate via dip-pen nanolithography.

We report a direct deposition strategy for sub-50-nm-scale uniform Au patterns on virtually any general insulating substrate via dip-pen nanolithography (DPN). In that process, HAuCl4 molecules were deposited onto bare insulating substrates via a molecular diffusion process, in the absence of electrochemical reactions. Subsequently, the generated HAuCl4 molecular patterns were decomposed to leave Au-only patterns using a thermal annealing process. Uniform Au patterns with a mean diameter of 47.9 ± 3.1 nm were achieved after the annealing process. The strategy allowed us to generate Au patterns on virtually any general insulating substrate (e.g., SiO2, Al2O3, polyimide, etc) without the need for surface functionalization or additional electrode structures. This versatile and reliable patterning method is expected to be useful in the future development of various novel industrial applications (e.g., mask or nanocircuit repair, nanosensors, etc.).