On-Wire Lithography (OWL)

The Mirkin group invented on-wire lithography (OWL), an electrochemistry-based method for performing lithography on one-dimensional nanowire materials in 2005, and co-axial lithography (COAL), a related method that can be used to control nanowire composition in the axial as well as radial dimension in 2015. In the original demonstration of OWL, striped multimetallic wires were prepared using template synthesis and then released from the template and deposited onto a glass slide. Next, metal or silica was deposited onto this slide, coating half of the nanowires, prior to their release from the slide. Upon chemical etching of sacrificial metal blocks, the placement of negative and positive features along the long axis of the wire could be controlled. Using OWL, billions of nanowires can be fabricated in parallel with control over wire diameter, composition, and feature size down to a single nanometer. COAL provides additional structural control; for example, plasmonic nanorings around and within semiconductor nanowires can be synthesized. Structures accessible via OWL and COAL have found use in plasmonics, biological labeling, molecular electronics (gaps tailored for molecular size and composition), energy conversion, and nanomechanics.

Above: Field-emission scanning electron microscopy (FESEM) images of an individual notched nanowire (inset) and hundreds of them after completion of the on-wire lithography (OWL) process. These rods are composed of Au and coated on one side with a bilayer consisting of 10 nm of Ti and 40 nm of Au. Wet-chemical etching was performed to remove the sacrificial silver segments to create the nanoscale gaps. Taken from Science, 2005, 309, 113.