氢等离子体处理对类金刚石膜场发射性能的影响

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

采用大功率、高重复频率、准分子激光溅射热解石墨靶制备了类金刚石膜,研究了直流辉光氢等离子体处理对类金刚石膜的场发射性能的影响。结果表明:氢等离子体处理后,类金刚石膜的场发射性能明显提高,其发射阈值电场由26V/μm下降到19V/μm。氢等离子体刻蚀除去了类金刚石膜生长表面的富含石墨的薄层,露出的新表面具有较低的功函数;膜表面的悬键被氢原子饱和,进一步降低了电子亲和势,改善了膜的场发射性能。

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.