Single-Walled Carbon Nanotubes as Shadow Masks for Nanogap Junction Fabrication*

We report a technique for fabricating nanometer-scale gaps in Pt wires on insulating substrates, using individual\textit{ single-walled carbon nanotubes} as shadow masks during metal deposition. 83{\%} of the devices display current-voltage dependencies characteristic of direct electron tunneling. Fits to the current-voltage data yield gap widths in the 0.8 - 2.3 nm range for these devices, dimensions that are well suited for single-molecule transport measurements.