真空度对碳纳米管场发射显示器的影响研究

Effects of Vacuum Levels on Carbon Nanotube-Field Emission Display

建立了碳纳米管场发射环境下电子与气体碰撞的数理模型。通过实验观察和理论分析说明:碳纳米管场发射显示器在常规阴阳极间距下,在不同真空度下的显示均为电子轰击荧光粉发光所致,在低真空度下也无气体放电产生紫外光致荧光粉发光;当真空度太低时,气体电离会降低实际加在阴阳极间的电压,致使电子无法发射。通过电子与气体分子的碰撞频率计算可以说明,用气体压力与阴阳极间距的乘积作为标准衡量气体对场发射的影响比仅用真空度来衡量更为合理。场发射显示器阴阳极间距越大,对真空度的要求越高。

A mathematical and physical model of electron-gas collisions is constructed. The experimental observation and theoretical analysis demonstrate that light emissions of a carbon nanotube-field emission display （CNT-FED） at different vacuum levels are mainly caused by electron bombardment on the phosphor. Light emission of the phosphor, excited by ultraviolet （UV） light derived from gas discharge, is not found even if the vacuum level is very poor. If vacuum level is too poor, a large amount of gas ionization will reduce the electric potential difference between the cathode and anode, so electrons are not emitted. The numerical calculations for the mean frequency of electron-gas collision indicate that the product of gas pressure and distance between the electrodes （pd） is a bet- ter parameter to characterize the effect of vacuum level for FED than gas pressure only, and when the distance be- tween the cathode and anode is increased, the vacuum level must be improved to obtain the same effect.