Field emission patterns from single-walled carbon nanotubes

A bulk bundle (with a diameter of about 100 mu m) of single-walled nanotubes (SWNTs), which were obtained after a purification process of carbon soot containing SWNTs, was used as an electron emitter. Many spikes of micro-bundles (with a typical diameter of 20-30 nm) of SWNTs extruded from the surface of the bulk emitter. Field emission originating from individual micro-bundles was observed on a fluorescent screen 50 mm apart from the tip. Each micro-bundle of SWNTs gave a corresponding bright spot, but no fine structure was observed within the bright spots. A probe hole device was used to measure an electron current from a single micro-bundle. The Fowler-Nordheim plot of the current and the applied voltage yielded a straight line, confirming the current results from field emission.