The electron field emission characteristics of the nitrogenated tetrahedral amorphous carbon (ta-C:N) films deposited by a pulsed filtered vacuum arc deposition system at various conditions were investigated. The wider region of N content in the films (0-21 at.%) allow us to study systematically the effects of N content and the other related parameters on field emission characteristics of the films. It was found that the field emission for both batches of ta-C:N samples depended upon the N content and this effect dominated the effects of the other parameters, such as sp(3) content, resistivity of the films, band gap of the films, and Fermi level position. The threshold field was found to first increase with increasing N content up to 5 at.%, then started to decrease up to a minimum of approximately 4 V/mum at 10 at.%. When the N content became higher than 10 at.%, the threshold field was found to increase again. Such complicated variation of the threshold field with the N content of the ta-C:N films was discussed in terms of a three-step field emission model. (C) 2003 Elsevier Science B.V. All rights reserved.