Large area metal nanowire arrays with submicron pitch and tunable sub-20 nm nanogaps

We present a new top-down nanofabrication technology to realize large area metal nanowire (m-NW) arrays with tunable sub-20 nm separation nanogaps without the use of chemical etching or milling of the metal layer. The nanofabrication technology is based on a self-regulating metal deposition process that is facilitated by closely spaced and isolated heterogeneous template surfaces that confines the metal deposition into two dimensions. Electrically isolated parallel arrays of m-NW can be realized with uniform and controllable nanogaps. Au-NW arrays are presented with high-density ~10⁵ NWs cm^-1, variable NW diameters down to 50 nm, variable nanogaps down to 5 nm, and very large nanogap length density ~1 km cm^-2. A spatially averaged surface enhanced Raman scattering (SERS) analytical enhancement factor of (1.5±0.2)×10⁷ is demonstrated from a benzenethiol monolayer chemisorbed on a Au-NW array substrate.