Fabrication of vacuum tube arrays with a sub-micron dimension using anodic aluminum oxide nano-templates

Vacuum tube arrays with a sub-micrometer dimension were fabricated by using anodic aluminum oxide (AAO) nano-templates. Ni nanowires deposited electrochemically inside the pores of the AAO nano-templates were used as the field emitters. The pores were sealed by means of angled evaporation of titanium. The field emission measurement was carried out in atmospheric environment outside of a vacuum chamber. The field emission characteristics show low turn-on voltages of 11.0–14.0 V. This phenomenon is attributed to the fact that the distances between the tips of Ni nanowires and the anodes are much smaller than those of conventional designs. Curvature in the Fowler–Nordheim plots at low applied voltage region is due to the variation of the enhanced field at each nanowire tip by the distribution in the length of Ni nanowires.