4-PROBE RESISTANCE MEASUREMENTS OF NICKEL WIRES WRITTEN WITH A SCANNING TUNNELING MICROSCOPE SCANNING ELECTRON-MICROSCOPE SYSTEM

We have used a scanning tunneling microscope (STM)/scanning electron microscope (SEM) system in ultra-high vacuum (UHV) to write nickel wires on silicon, forming connections between prefabricated four-probe contact pads. We leak nickel carbonyl into the STM chamber to a set pressure. We then use the STM tip as a local source of electrons to decompose the nickel carbonyl which has adsorbed to the surface of the substrate. Auger analysis indicates that 95% of the material in our deposits is nickel. Nickel wires as small as 50 nm in width have been fabricated in this way. Previously, we have fabricated nonmetallic wires as small as 10 nm in width, thus demonstrating the potential for the technique. A low-temperature, four point resistance measurement indicates that our nickel wires are conductive and metallic. We estimate that their resistivity at 77 K is approximately 25-mu-OMEGA . cm. This is the first report of a four-point measurement on an STM-written structure.