Nanowire lithography: fabricating controllable electrode gaps using Au-Ag-Au nanowires.

A method to fabricate nanowire electrodes possessing controllable gaps is described. The method relies on electrochemical deposition and selective chemical etching or heating to selectively remove the Ag segment of Au-Ag-Au nanowires. Because the thickness of the Ag segment directly dictates the size of the nanogap, the gap width can be easily controlled during the nanowire fabrication process. Herein, we demonstrate gaps with 2 microm, 100 nm and 20 nm widths via the above-mentioned approaches. In addition, we observed that small gaps (approximately 20 nm) can be formed through annealing Au-Ag-Au nanowires at 200 degrees C in air. Electrical contact between nanowire electrodes and contact pads is studied. Using nanowire electrodes with a 100 nm gap, we subsequently fabricate organic field effect transistors (FETs) with regioregular poly(3-hexylthiophene).