Field emission properties of bare and gold-coated nickel nanowires grown in polymer ion-track membranes

The authors have measured the field emission properties of freestanding bare and Au-coated Ni nanowires randomly distributed on thin metallic substrates. The nanowires of uniform length and diameter were grown in the etched ion-tracked pores of polycarbonate membranes by electrochemical deposition. While bare Ni samples yielded only 1.6x10(4) emitters/cm(2) at 10 V/mu m, Au coating of the Ni nanowires improved the emission site density to 1.4 x 10(5)/cm(2) at 5 V/mu m and about 1.6x10(6) emitters/cm(2) at 18 V/mu m. Average field enhancement factors beta of 331 for bare Ni and 302 for Au-coated Ni nanowires correspond well to their cylindrical shape in the scanning electron microscope images. Stable Fowler-Nordheim-like emission was obtained on average up to currents of about 0.4 and 8 mu A for bare and Au-coated Ni nanowires, respectively. Locally measured I-V curves, maximum current I-max, and derived beta values hint for the clustering of nanowires. (c) 2007 American Vacuum Society.