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

摘要

Arrays of vertically aligned carbon nanotubes (CNTs) were grown on a patterned sputtered cobalt film by chemical vapor deposition from ethylenediamine at 900℃. 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) cm~(2). 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/cm~(2). 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.