Abstract
We report the fabrication of metallic nanowires and nanoelectrodes by atomic force microscopy (AFM). Nanopatterns are first created on a PMMA film by force lithography. By further metal film coating and lift off processes, metallic nanowires are constructed. In additional, nanoelectrodes can be produced by direct cutting a nanowire with the AFM tip. Electrical properties of the nanoelectrodes have also been explored. A 50 nm thick PMMA coated on a silicon oxide substrate is first scratch by the AFM tip to create grooves. Gold and copper films with thicknesses of 2 and 22 nm, respectively, are evaporated onto the sample subsequently. Metallic nanowires with 60 nm in width and 24 nm in height are obtained after lift off. The I-V curve of a nanowire follows Ohm’s law, but its conductance is less 26 times than bulk materials. We consider that the reduction of conductance is due to change of material properties rather than the size effect. Nanoelectrodes with a gap of around 50 nm are then created by directing a nanowire with the AFM tip. By applying a voltage of 0.9 V between the electrodes, the tunneling current is observed. If the voltage is lager, e.g. 2 V, the atoms of the electrodes will be attracted between two electrodes and form an atomic scale junction. This junction will break again by applying 0.3 V due to electromigration and form an atomic scale gap. When the finest point of the nanowire is reduced to a number of atoms, the conductance decreases stepwise.