学术论文

      碳纳米管场发射器件放气特性分析及其对场发射性能的影响

      Outgassing Analysis of the CNTs Field Emission Devices and Its Influence on Field Emission Performance

      摘要:
      为了研究场发射冷阴极电流跌落机制,采用四极质谱仪实时分析的方法研究了碳纳米管阴极场发射器件的放气特性及工作状态下器件内残余气体对阴极场发射性能的影响.结果表明:碳纳米管阴极场发射器件工作时,放出气体的主要成份是H2,CO2,CO;随着阴极发射电流密度的增加,气体成份的分压也随着增加.碳纳米管阴极的场发射性能,例如开启场强、阈值场强和场发射电流密度都与放出气体压强密切相关.碳纳米管阴极在压强为2.1×10-3 Pa的残余气体环境下工作1.5 h后,开启场强和阈值场强相应增加了29.4%和50.0%.阴极受残余气体影响,一方面阴极发射材料表面功函数增加;另一方面阴极发射体场增强因子减小.增大的功函数和减小的场增强因子降低了阴极的场发射性能.因此,场发射器件放气是阴极电流跌落的重要原因.
      Abstract:
      To study the mechanism of current degradation of a cold cathode,the ougassing analysis of a field emission diode with screen-printed carbon nanotubes(CNTs) cathode has been taken with a quadrupole mass spectrometer(QMS) in an ultra-high vacuum (UHV) system.It was found that H2,CO2 and CO were outgassed from the diode during the working process.The partial pressure of outgassing increases with the increased emission current density.The field emission properties of the cold cathode,such as turn-on field,threshold field and the emission current density,were largely related to the pressure of the outgases.After the CNTs cathode had 1.5 hour field emission operation at 2.1×10-3 Pa total pressure,the turn-on field and threshold field increased 29.4% and 50.0% respectively compared with their original values.Due to the outgassing,the work function of CNTs cold cathode increased,while the field enhancement factor decreased.Increasing the work function and reducing the field enhancement factor decrease the field emission characteristics of the cathode.Therefore,the outgassing plays very important role in the current degradation for the field emission devices.
      作者: 崔云康 [1] 狄云松 [2] 陈静 [3] 唐春红 [1]
      Author: Cui Yunkang [1] Di Yunsong [2] Chen Jing [3] Tang Chunhong [1]
      作者单位: 南京工程学院数理部,江苏南京,211167 南京师范大学物理科学与技术学院,江苏南京,210023 东南大学电子科学与工程学院,江苏南京,210096
      年,卷(期): 2017, 40(1)
      分类号: O462.4
      在线出版日期: 2017年6月2日
      基金项目: 国家自然科学基金,江苏省自然科学基金,南京工程学院自然科学基金