Who: Pablo Ares, Department of Physics and Astronomy & National Graphene Institute, University of Manchester, UK
Place: Donostia International Physics Center
Date: Friday, 18 October 2019, 12:00
The continuous reduction in size of micro- and nanocircuits is pushing the limits of the available technologies. The electrical characterization of nanomaterials with promising applications almost always requires the fabrication of nano-sized metal electrodes. However, the current fabrication techniques present some limitations that prevent their use in some of the most demanding applications. We have developed a new technique for fabricating nanoelectrodes for the characterization of electrical transport properties at the nanoscale. We use an atomic force microscope (AFM) tip to manipulate gold nanowires (?50 nm in diameter and 5 Ám in length) and join them together by cold welding . Due to the enormous surface to volume ratio of the nanowires, it is enough to push one nanowire against another with the tip of an AFM to form an excellent weld . This way we form highly conductive complex reconfigurable nanostructures, which allow the electrical connectivity and characterization of other nano-objects in a clean and simple way, since this technique does not require the use of polymers or chemicals. Therefore, this new method, called SPANC (Scanning-Probe-Assisted Nanowire Circuitry) can complement and/or be an alternative to other methods to fabricate nanocircuits.
I will present some examples that illustrate the capabilities of SPANC, which includes the fabrication of robust devices for the electrical characterization of various nano-objects with sizes down to ?10 nm, well below the smallest nano-object size that can be contacted in a device-type configuration with the currently available standard technology (?30 nm). I will show examples of electrical characterization of different materials (graphene, carbon nanotubes or antimonene); different measurement configurations, such as an electrode of gold nanowires (with a conductive AFM tip as a second mobile electrode) and more conventional devices of 2 and 4 gold nanowire electrodes; or their introduction in the field of molecular electronics, studying the electrical transport properties of 1,4benzenedithiol molecules.
 M. Moreno-Moreno, P. Ares et al., AFM manipulation of gold nanowires to build electrical circuits Nano Lett. 2019, 19, 5459?5468.
 Y. Lu et al., Cold welding of ultrathin gold nanowires. Nat. Nanotechnol. 2010, 5, 218?224.