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/sup +/) into ta-C films at ion energy of 6 keV with different dose from 1.7 to 20/spl times/10/sup 15/ atoms/cm/sup 2/. 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 /spl mu/A to doped 80 /spl mu/A. The low turn-on field of about 14 V//spl mu/m 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/sup +/ doping through raising the Fermi-level (E/sub F/) toward the conduction band of ta-C films.