测试环境对碳纳米管场发射性能的影响

Effects of test environment on the field emission properties of carbon nanotubes

采用CVD法在Ni丝上直接沉积碳纳米管,并应用二极管结构对其场发射性能进行测试,测试结果表明:(1)碳管表面态对其场发射稳定性影响明显,运用密度泛函平面波赝势方法(PWP)和广义梯度近似(GGA)对碳管表面吸附水分子前后电子能带结构和态密度作比较,发现吸附水分子后碳管功函数降低,费米能级处电子态密度增大,有利于增大碳管场发射电流;(2)高真空是获得碳管场发射稳定性一个必要条件;(3)荧光粉对碳管场发射电流也有一定贡献,但大的场发射电流情形下可忽略其影响。

CNT-Ni wires were fabricated by the direct depositon of CVD method,and the field emission properties were tested by the diode-type configuration. Test results show that （1） the surface states of CNT have an obvious impact on the stability of field emission.PWP and GGA were adopted to simulate the band structures and electron density states of CNT before and after the surface adsorption of H2O molecular,the changes of band structure and electron density states show that the adsorption of H2O molecular has an enhancement to the filed emission current; （2） high vacuum is an indispensable condition to the stability of filed emission of CNT.（3） Phosphor also has a certain contribution to the current,but the impact can be ignored under a large field emission current.