Field emission studies of nitrogen-doped diamond-like carbon films deposited using CH4/N-2/Ne and CH4/NH3/Ne RF plasmas

Hydrogenated diamond-like Carbon (DLC) films have been deposited on Si subs trates using CH4-based radio-frequency plasmas. The films have been doped w ith nitrogen by addition of either N-2 or NH3 into the source gas mixture, producing films with up to 16% and 25% N content, respectively. The effect of additions of Ne to these gas mixtures has been investigated as a possibl e method to increase the growth rate and the N-content of the films. We fin d that addition of Ne increases the film growth rate until the Ne now rate equals that of the CH4, giving maximum growth rate increases of 70% and 200 % for NH3 and N-2 containing gas mixtures, respectively. At the same time t he field emission threshold voltage decreases by a factor of similar to 0.5 and 2, respectively. With further increases in Ne flowrate,the film growth rates decrease in both cases, whilst the threshold voltage increases. Micr o-combustion measurements show that the N content within the films is propo rtional to the percentage of the N-containing precursor in the gas phase, b ut is independent of Ne concentration.