Properties of nitrogen-doped diamond-like-carbon films prepared by a laser ablation

We have successfully introduced nitrogen into diamond-like-carbon films by evaporating carbon and nitrogen ions simultaneously from a carbon target dipped in hexamethylenetetramine solution with a laser. Nitrogen content in the film was changed by varying the molar concentration of hexamethylenetetramine solution. This method needs no vacuum arc and provides a simple effective way of nitrogen addition. The resistivity measured as a function of nitrogen content decreases up to a certain nitrogen content and then increases at higher nitrogen content, suggesting that nitrogen act as a true dopant. Atomic force microscopy and Raman spectroscopy studies also suggest that no graphitization whatsoever occurs in the films after nitrogen addition. Although no structural change in the films was found with nitrogen addition, the emission threshold field decreased by ;4–5 Vrmm depending on nitrogen content. The nitrogen-added diamond-like-carbon film was found to have a typical threshold field of ;10 Vrmm at optimal composition. q1999 Published by Elsevier Science B.V. All rights reserved.