Planar nanocontacts with atomically controlled separation

We have developed a technology to reproducibly make gaps with distance control on the single-atom scale. The gold contacts are flat on the nanometer scale and are fabricated on an oxidized aluminum film that serves as a gate. We show that these contacts are clean and can be stabilized via chemical functionalization. Deposition of conjugated molecules leads to an increase in the gap conductance of several orders of magnitude. Stable current-voltage characteristics at room temperature are slightly nonlinear. At low temperature, they are highly nonlinear and show a clear gate effect. (C) 2003 American Institute of Physics.