Controlled fabrication of DNA molecular templates for the deposition and electrical measurement of 1D metal nanowires

Stretched DNA nanowires (NWs) offer a convenient substrate for the fabrication and measurement of 1D metal NWs of width down to nm [1].So far the fabrication of the DNA templates has replied on somewhat random self-assembly processes. Here we demonstrate a process with high degree of control over the length, spacing, diameter , and orientation of the metal NWs: A one-step dewetting of a DNA solution on a PDMS stamp with an array of micropillars with well-defined pitch yields DNA NWs suspended across the micropillars along a chosen direction [2]. The DNA NWs are then transferred via micro-contact printing onto a Si/SiO2/SiNx substrate with a lithographically fabricated trench defined by an opening in the SiNx layer and undercut in the SiO2 layer. The template with DNA NWs stretched across the trench is placed in a high-vacuum evaporator for metal deposition, resulting in a metal NW of width defined by the diameter of the DNA template (\textless 10 nm) and length determined by the width of the trench. Quasi-four terminal I-V measurements are performed in situ with incremental metal deposition. Concomitant with a transition from strongly nonlinear IV to Ohmic behavior with increasing thickness, the NW resistance is observed to decrease exponentially. [1] Hopkins, David S., et al. Science 308.5729 (2005): 1762-1765. [2] Guan, Jingjiao, et al. Soft Matter 3.11 (2007): 1369-1371.