Connection of nanostructures using nanowires grown by a self-field emission process

Abstract

A technique for growing single metallic nanowires through a process of field-emission from a pointed structure is described. The field-emission of electrons in the presence of metal-carbonyls results in the deposition and growth of nanowires with diameters typically ranging from 3 to 30 nm, depending on the precursor used and growth conditions. Lengths range typically from several to tens of microns. Transmission electron microscope analysis of the nanowires shows that they are overcoated with a thin (∼nm) layer of carbon which prevents the oxidation and corrosion of the encapsulated wire. Tungsten, iron and cobalt nanowires have been grown from their respective carbonyls. Current-voltage measurements of tungsten nanowires show ohmic behaviour at room temperature, yielding resistivity values 11-17 times that of bulk tungsten. Tungsten wires with inner core diameters of 4-5 nm are able to withstand current densities of greater than 5×1011 Am-2 before failure. Free-standing nanowires thus grown from vertically-aligned nanostructures such as carbon nanotubes can be made to contact a substrate electrode by electrostatic attraction. The technique opens up the possibility of making electrical contacts to nanostructures that are otherwise not easily contactable.