碳纳米管薄膜的场发射及其有效发射面积

Field Emission Characteristics and Effective Emission Area of Carbon Nanotube Films

讨论了薄膜与阳极间隔以及有效发射面积对碳纳米管薄膜场发射性能的影响。以磁控溅射Al和Ni在Si片上做为缓冲层和催化剂,以乙炔为C源气体,利用化学气相沉积法制备了碳纳米管薄膜。扫描电镜观测结果表明,碳纳米管的直径为50～80nm。采用二极管结构,测试了样品的场发射性能,结果表明碳纳米管薄膜具有优异的场发射特性,薄膜与阳极距离为400μm时开启场为0.85V/μm、阈值场为1.22V/μm。F-N理论计算结果表明,碳纳米管薄膜的有效发射面积几乎不随场发射所加电压的变化而改变;有效发射面积随着薄膜与阳极距离的增加而增大。

Effects of the sample-anode distance （the interval between sample and anode） and effective emission area on the field emission characteristics of carbon nanotube films were discussed. Si substrate was coated with Al and Ni films as the buffer layer and catalyzer in sequence by a magnetic sputtering method, and carbon nanotube films were grown on Si substrate by thermal chemical vapor deposition with acetylene as the precursors. The SEM was used to determine the structure of the films. The results show that the diameters of carbon nanotubes are 50- 80 nm. The field emission properties were tested on the CNT-anode setup, and the mesurement results indicates that the low turn-on field is 0.85 V/μm and threshold field is 1.22 V/μm at the sample-anode distance of 400 μm. Effective emission area was extracted from the F-N plots at different sample-anode distances, which shows the area increases with sample-anode distance increasing. The emission area was estimated also from the F-N equation, which indicates that the emission area slightly changes with electric field, regardless of the sample conditions.