Robust Ohmic contact junctions between metallic tips and multiwalled carbon nanotubes for scanned probe microscopy

We demonstrate a simple method that uses a scanning electron microscope for making a reliable low resistance contact between a single multiwalled carbon nanotube and a metallic tungsten probe tip or a Si cantilever. This method consists of using electron beam induced decomposition of background gases and voltage pulses to remove contaminants. The electrical quality of the contact is monitored in situ by measuring the current flow at constant bias or by observing the decay of current fluctuations. The quality of the contacts is confirmed via current-voltage spectroscopy. This method produces very stable, low resistance, mechanically robust contacts with high success rates approaching 100%.We thank T. L. Williams at Harvard for the cantilever fabrication. This work is supported by the NSF (Grant No. DMR-0308575) and the Welch Foundation (Grant No. F-1533)