Electron field emission properties of as-deposited and nitrogen implanted tetrahedral amorphous carbon films

Tetrahedral amorphous carbon (ta-C) films have been prepared at ambient temperature by filtered arc deposition (FAD). Electron field emission properties of the ta-C films were studied using a parallel plate diode configuration. Research indicated that a threshold electric field of about 16 V/μm is required to initiate the electron emission from the as-grown ta-C film. An emission current of ∼20 μA was detected at an electric field of around 20 V/μm, following the Fowler–Nordheim (FN) field emission behavior. In order to investigate the effect of nitrogen on the field emission of ta-C, nitrogen ions were implanted into the ta-C films at an ion energy of 6 keV with ion dose varying from 1.7 to 20×1015 atoms/cm2. It was found that the emission current and the threshold electric field are in close relationship with the ion dose. At the highest ion dose, the emission current increases to ∼80 μA. Correspondingly, the threshold electric field decreases from 16.7 to 14 V/μm. The FN behavior was also observed for the nitrogen implanted ta-C films. However, the degradation of the field emission properties is found when a lower dose of nitrogen is implanted into the films. The mechanism for the modification of field emission properties by nitrogen implantation is discussed.