N离子注入对金刚石膜场发射特性的影响

不同剂量的N离子被注入到化学气相沉积金刚石膜内，研究了表面结构及场发射特性的变化.Raman谱和x射线光电子能谱分析表明，N离子的注入破坏了金刚石膜表面原有的sp3结构，并在膜内形成大量的sp2 C—C 和sp2 C—N 键.样品的场发射测试显示N离子的注入显著提高了金刚石膜场发射特性，膜的场发射阈值电场从注入前的18 V/μm下降到注入后的4 V/μm.金刚石膜场发射特性的提高归因于N离子注入后膜内sp2 C键含量的增加和体内缺陷带的形成，这些变化能改变膜的表面功函数，提高Feimi能级，降低电子隧穿表面的能量势垒. 关键词： 场致电子发射 N离子注入 金刚石膜 热丝化学气相沉积

The effect of nitrogen-implantation on the field-emission properties of CVD diamond films

Nitrogen was implanted into the chemical vapor deposition(CVD) diamond films, and the electron field emission properties of the nitrogenated diamond films were investigated. Raman and x ray photoelectron spectroscopy(XPS) measurement revealed that nitrogen implantation damaged the structure of diamond film and promoted the formations of sp2 C—C and sp2 C—N bonding. By increasing the implantation dose， the threshold field of the emission of the diamond film could be lowered from 18V/μm to 4V/μm. The enhancement of field emission for nitrogen implanted CVD diamond films was attributed to the increase of the fraction of sp2 C bonds and the formation of defect bands within the bulk diamond band gap induced by nitrogen implantation, which could alter the work function and elevate the Feimi level. Consequently, the energy barrier on diamond surface for electron tunneling was reduced.