Field emission of copper nanowires grown in polymer ion-track membranes

Field emission properties of randomly distributed copper nanowires are presented. The wires were potentiostatically deposited into the pores of polycarbonate membranes produced by the ion-track etch technique. The diameter and length of the vertically aligned wires with number densities between 106 and 108 wires/cm2 were in the range of 210–330 nm and 8–18 μm, respectively. By means of field emission scanning microscopy, emission site densities between 0.4 × 105 cm−2 and 1.4 × 105 cm−2 were obtained for nA currents at 6 V/μm. Two-thirds of the nanowire emitters showed Fowler–Nordheim behaviour with an average field enhancement factor of β = 245, which is about three times higher than expected for a cylindrical wire geometry with a half-sphere tip.