Enhanced field electron emission from nitrogen doped tetrahedral amorphous carbon film

Nitrogen doped tetrahedral amorphous carbon (ta-C) films were prepared by implantation of nitrogen ions (N⁺) into ta-C films at ion energy of 6 keV with different dose from 1.7 to 20×10 ¹⁵ atoms/cm². The effect of nitrogen doping on the field emission behavior of ta-C film is investigated in detail. It was found that the emission current is in close relationship with the doping dose. At a suitable doping dose, the emission current was increased from undoped 20 μA to doped 80 μA. The low turn-on field of about 14 V/μm and Fowler-Nordheim behavior were also observed. The mechanism for field emission from nitrogen doped ta-C films was discussed. It was considered that the improvement of field emission arises from the increase of carrier concentration and the decrease of effective emission barrier by N⁺ doping through raising the Fermi-level (E_F ) toward the conduction band of ta-C films