Stable and uniform electron emission from nanostructured carbon films

We have systematically studied the electron-emission characteristics of nan ostructured carbon films with various amounts of-nanoclusters and degrees o f nanotube alignment. According to our observation, the dense packing and/o r alignment of nanotubes is detrimental to the low-field emission, which we attributed to the electrostatic,screening effect. The best emission was ob served from the carbon films dominated by nanoclusters; the turn-on field w as 1.6 V/mum and the emission-site density was considerably higher than 5 X 10(4) site/cm(2). The emission from the nanocluster-dominated him was unif orm and stable. Raman spectroscopy identified the nanoclusters as crystalli ne graphite with some structural defects. It is conceivable that the modifi cation of the boning hybridization at the cluster surface resulted in a dia mond-like density of states, and that the corresponding small electron affi nity was responsible for the excellent emission the from nanoclusters. (C) 2001 American Vacuum Society.