Free Standing Nanocrossbar Arrays with Molecular Throughput

Abstract

We report a new approach for fabricating vacant nanocrossbar arrays using a combination of lithography and selective chemical etch. Two parallel arrays of gold wires are lithographically patterned orthogonal to each other with a chromium layer (2-5 nm thick) sandwiched between the wire arrays. A silicon oxide mesh is sputtered over the metal ensemble leaving the crossing points free of the oxide layer. The chromium layer is subsequently removed via selective chemical etch leaving a gold architecture with vertical separations that are on the order of a few nanometers. The silicon oxide mesh anchors the gold wires in place creating a robust nanoarchitecture. The nanogaps can be filled with fluids resulting in a change of the junction's resistance. The variability in the vertical separations between the wires within an array is only a few Angstroms. These results demonstrate that molecular-sized gaps can be created without the use of a molecular template.