溶液法制备的碳纳米管薄膜的结构分析与场致电子发射机理研究

结合紫外光电子能谱和拉曼光谱对溶液法制备的碳纳米管薄膜的场致电子发射性能进行研究。采用溶液滴涂法制备的碳纳米管薄膜的场致电子发射开启电场约为3.33 MV/m,阈值电场约为5.44 MV/m,以福勒-诺得海姆(Fowler-Nordheim,FN)理论对电子发射进行解释,其发射的增强因子接近103。通过对紫外光电子能谱的分析,发现碳纳米管薄膜的低能量截止端在外加电场作用下逐步降低,表明纳米管薄膜的表面有效势垒在外加电场作用下逐步下降,从而使得碳纳米管薄膜的电子更加容易发射进入真空。结合拉曼光谱和电学特性的研究,发现界面过渡层的接触电阻与碳纳米管薄膜中的非晶碳成分均可以增强场致电子发射。

Study on the Field Emission Characteristic of Carbon Nanotube Thin Film Prepared by Solution Method

A carbon nanotube(CNT) thin film field emission cathode was prepared by drop casting method,and its field emission characterisitic was studied by ultra violet photoelectron emission spectroscopy and Raman spectroscopy.The results indicated that the field emission curves of the CNT thin films obeyed the Fowler-Nordheim(FN) theory.The minimum turn-on field and the threshold field were 3.33 MV/m and 5.44 MV/m,respectively.The field enhancement factor was found to be around 103.The ultraviolet photoelectron emission spectral analysis showed that the low-energy cut-off edge of the CNTs thin film gradually decreases as the applied bias increases,which indicated that the applied bias has pull down the effective emission barrier greatly so that electrons can emit at smaller electrical field without geometric enhancement.The reduction of effective emission barrier is explained by the contact effect from the CNTs/Ni interface.In addition,the bias drop on the thin film also leads to the reduction of the surface barrier,which is particularly obvious in the unpurified CNTs thin film,and it is related to the residue of amorphous carbon(a-C) in the thin film.