Field emission from a mixture of amorphous carbon and carbon nanotubes films

A mixture of amorphous carbon and carbon nanotubes films was synthesized on stainless steel plates by a microwave plasma enhanced chemical vapor deposition system. The source gases were hydrogen and methane with flow rates of 100 and 16sccm, respectively, with a total pressure of 5.0 kPa. The surface morphology and the structure of the films were characterized by field emission scanning electron microscopy (SEM) and Raman scattering spectroscopy. Field emission properties of as-deposited film were measured in a vacuum room below 5 × 10-5 Pa. The experimental results show that the initial turn-on field is 0.9V/μm; The current density is 4.0mA/cm2 and the emission sites are dense and uniform at an electric field of 3.7V/μm. These results indicate that such a mixture of amorphous carbon and carbon nanotubes films is a promising material for field emission applications.