Field-emission properties of aligned carbon nanotubes

Dense, well-separated, and aligned carbon nanotubes have been prepared via bias-enhanced microwave plasma chemical vapor deposition. The turn-on fields defined at the emission current density of 10 mu A/cm(2) are about 3.35 V/mu m, 2.54 V/mu m, and 3.54V/mu m, for the immersion times in PdCl2 of 1 min, 20 min, and 40 min,respectively. The corresponding emission current densities are about 0.97 mA/cm(2), 4.5 mA/cm(2), and 0.44 mA/cm(2) at the electric field of 5 V/mu m. The higher emission current obtained from the aligned carbon nanotubes for the immersion time of 20 min is ascribed to the denser and sharper nanotubes formed in this condition.