Single-wall carbon nanotube conducting probe tips

We describe a method for producing and characterizing electrically connected single-wall carbon nanotube scanned-probe tips. The stable contact resistance, of the order of 100 kOmega, makes these tips suitable for conducting probe applications. The nanotubes, grown by chemical vapor deposition, are mounted on the end of metal-coated (gold and platinum) silicon tips, using the "pick-up" method. Electrical characterization is carried out by lowering the tube into a liquid mercury contact and measuring the current through the tube as a function of applied bias voltage and immersion depth. This allows assessment of the magnitude and stability of the contact resistance, as well as identification of metallic and semiconducting tubes. It also offers a new geometry for investigating the transport properties of a nanotube as a continuous function of its conducting length.