Effect of hydrogen plasma treatment on the field emission of diamond-like films deposited by high power excimer laser ablation

The effect of hydrogen plasma treatment on the electron field emission of diamond-like carbon films (DLCs) deposited by high frequency and high power pulsed XeCl excimer laser ablation of pyrolytic graphite targets at room temperature was studied. Results indicated that the films exhibited improved electron emission, with the threshold field of the films decreased from 26 to 19 V/μm. Meanwhile, the current density increased considerably after the treatment. Two factors were responsible for the results. One was that the graphite-rich DLC film surface formed with low energy carbon atoms or clusters during growth process was removed by the hydrogen plasma with the formation of a new surface comprised of high density sp³ bonded carbons, which exhibited a low electron affinity and good field emission . The other was that the dangling bonds of the carbon atoms on the film surface were saturated with H-atoms after the treatment, which further decreased the electron affinity.