等离子体表面氮掺杂对非晶碳膜场发射特性的影响  

The Improvements in Field Electron Emission Characteristics of Amorphous Carbon Films due to Nitrogen Surface Doping

作　　者：李伟[1] 岑展鸿[1] 钱波[1] 梅嘉欣[1] 徐骏[1] 陈坤基[1] 

机构地区：[1]南京大学物理系固体微结构物理国家重点实验室,南京210093

出　　处：《南京大学学报（自然科学版）》2006年第4期346-350,共5页Journal of Nanjing University（Natural Science）

基　　金：国家自然科学基金(50472066;90301009);国家重点基础研究发展规划(973)项目(2001CB610503)

摘　　要：氢化非晶碳膜作为一种场致阴极电子发射材料已被广泛研究,通过对薄膜进行掺杂以提高其场发射特性已被证明是行之有效的方法之一.利用常规等离子体化学气相淀积技术制备了氢化非晶碳薄膜材料,在原位利用氮等离子体对碳膜表面进行N型掺杂.通过不同手段研究了氮表面掺杂前后非晶碳膜的微结构和化学键的变化,对表面掺杂前后的薄膜的场电子特性的测量表明,在氮表面掺杂后其场电子发射特性有了明显改善,特别是场发射的阈值电场从掺杂前的3.2 V/μm下降到掺杂后的1.0 V/μm.初步实验分析表明:由于氮表面掺杂后,在碳膜表面形成N-H键,从而导致碳膜表面的有效功函数降低使场电子发射特性得以提高.Hydrogenated amorphous carbon films have been widely investigated as one of cathode field emission materials. It has been recognized that the film microstructures, surface chemical compositions and even the film thickness can strongly influence the electron emission characteristics from amorphous carbon materials. By using Ar, H and O2 plasma to treat amorphous carbon film surface, the field emission characteristics can be modified obviously due to the modification of the film surface configurations and morphology. It has been verified that doping of nitrogen in the films is one of the effective ways to improve the field emission characteristics. In this paper, we prepared hydrogenated amorphous carbon films in conventional r. f. plasma enhanced chemical vapor deposition （PECVD） system at low substrate temperature and performed N type in situ doping on the surface of carbon films by nitrogen plasma surface treatments. The change of the surface structures and bonding configurations were investigated by different measurements techniques for samples with and without nitrogen surface doping. The field electron emission characteristics of the films before and after nitrogen surface doping were studied and it is shown that the field emission properties had been improved obviously, especially the threshold electric field for electron emission which is defined as the electric field at the emission current density of 10^-6 A/cm^2. The threshold electric field is reduced from 3. 2 V/μm to 1.0 V/μm after nitrogen surface doping. Preliminarily analysis showed that the improvement of field emission properties can be attributed to the decrease of the effective work function of the front surface of amorphous carbon film due to the formation of N-related states on the surface after nitrogen plasma surface doping.

关 键 词：场发射 氢化非晶碳 表面掺杂 

分 类 号：TN412[电子电信—微电子学与固体电子学]