Enhancement of electron field emission from carbon nanofiber bundles separately grown on Ni catalyst in Ni–Cr alloy

The enhancement of electron field emission was successfully obtained from carbon nanofiber (CNF) bundles separately grown on Ni grains in Ni–Cr alloy compared with that from CNF bundles on pure nickel. Ni grains less than 1 μm in size were separated by Cr grains in the alloy prepared by cosputtering with Ni pellets on a Cr plate without a lithographic patterning process. CNFs grew on Ni grains as bundles of 100 nm diameter and 1 μm length by helicon wave plasma-enhanced chemical vapor deposition, controlling the distance between adjacent CNF bundles by 500–1000 nm. The field emission characteristics of electrons from CNF bundles were evaluated and compared using current–voltage characteristic curves and a Fowler–Nordheim (F–N) plot converted using a work function value of 4.7 eV for CNFs. The field enhancement factor of FE characteristics obtained from the slopes in the F–N plot increased with the average distance defined as the space between adjacent CNF bundles. CNFs separately grown on a Ni–Cr catalyst are a candidate for effective two-dimensional field emitter devices.