Field emission characteristics of mixture films of nano-structure amorphous graphite and carbon nanotubes

The mixture film of nano-structure graphite and carbon nanotubes was fabricated on Titanium coated ceramic substrate by microwave plasma chemical vapor deposition system (MPCVD). The source gas was a mixture of H-2 and CH4 with flow rates of 100 sccm and 12 sccm, respectively. During the deposition, the total pressure of 6.0 KPa, substrate temperature of 850degreesC and microwave power of 1500W were kept for 2 hours. The surface morphology and the nano-structure of the film were examined using field emission scanning electron microscopy, X-ray diffraction, Raman scattering spectroscopy and X-ray photoelectron spectroscopy. Field emission of the film were carried out in a vacuum chamber with base pressure of below 5x10(-5) Pa. The initial tum-on field was 0.6V/mum and 1.7 mA/cm(2) of current density at 1.7 V/mum was obtained. The stability of the emission was tested by maintaining the electric field at 1.8 V/mum. The experiments indicate that the film is an efficient and stable cathode material at low electric field.