Field Electron Emission from Caterpillar-Like Clavae Nano-Structure Carbon Thin Films

Nano-carbon films with large density of caterpillar-like clavae are synthesized by microwave plasma-assisted chemical vapor deposition using a mixture of methane and hydrogen gases on Mo film substrates. The films are characterized by Raman spectra, optical microscopy and field emission scanning electron microscopy. Field electron emission measurements of nano-carbon films are also carried out to show the turn-on field as low as 1.5 V/μm and the high current density of 2.2 mA/cm² at electric field of 5.7 V/μm, the uniformly distributed emission site density from a broad well-proportioned emission area of about 4.0 cm² is also obtained. The field-emission current density J versus macroscopic electric field E does not follow the original Fowler-Nordheim (F-N) relation since they are not well represented in the F-N plot by a straight line. A modified F-N relation is applied successfully to explain all the field-emission data observed for E<6.0 V/μm.