Field emission from carbon nanotubes grown on a tungsten tip

Field emission microscopy studies of carbon nanotubes grown by the pyrolysi s of ferrocene on a tungsten field emitter are reported. A field emission c urrent density of 1.5 A cm(-2) has been drawn from such an emitter at a fie ld of 290 V/mum, and this density is considerably higher than that found wi th planar cathodes. Accordingly, the field enhancement factor, calculated f rom the slope of the F-N plot in the low field region is also large. Field emission micrographs reveal the lobe structure symmetries typical of carbon nanotube bundles. The emission current is found to be remarkably stable ov er an operating period of more than 3 h for current values of up to 500 muA . (C) 2001 Published by Elsevier Science B.V.