High-current field emission from a vertically aligned carbon nanotube field emitter array

Abstract

Arrays of vertically aligned carbon nanotubes (CNTs) were grown on a patterned sputtered cobalt film by chemical vapor deposition from ethylenediamine at 900°C. Each square array comprises a moderate density of nanotubes with an average height of 90 μm covering a total area of 3.6 × 10-3 cm2. Field emission measurements were carried out on individual arrays at pressures below 10-8 mbar. The spacing between the anode and the top of the CNT array is 935 μm and a total current of 2 mA could be obtained at 2.5 kV. A Fowler-Nordheim plot of the I-V data shows an unusually high field enhancement factor at lower fields. At an average field strength of 1.925 V/μm, the corresponding emission current density is 130 mA/cm2. This emission current was found to be very stable, with short-term fluctuations (5 Hz measurement bandwidth) of no more than ±1.5%, while the current drifted less than 1.5% over a test period of 20 h. © 2001 American Institute of Physics.