Growth and high current field emission of carbon nanofiber films with electroplated Ni catalyst

Abstract

We report high current-density field emission from carbon nanofiber (CNF) films synthesized using electroplated Ni catalysts on gold-buffer layers via hot-filament chemical vapor deposition. High-density thick CNFs which had a solid structure without hollow cores and many protrusions on the outside of CNF body were formed. The protrusions consisted of buckled small graphitic sheets, and some protrusions had very small tip radius to which we attribute good field emission from CNF films. The maximum emission current of 3.67 mA was measured from the area of 4.9 × 10 − 3 cm 2, corresponding to the current density of 750 mA/cm 2, at the electric field of 12.5 V/μm. There was a distinctive hysteresis in emission–current curves measured while ramping up and down the bias-voltage. The deviations between up- and down-sweep emission currents, and the slope change in Fowler–Nordheim curves were most prominent in medium-voltage and -current regime. Moreover, the emission–current hysteresis showed dependence on the pressure during measurement and the voltage-sweep speed. We propose that adsorbate-enhanced field emission and adsorbate desorption during field-emission measurement were responsible for the observed emission behavior.