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采用双向电泳法,在原子力显微镜探针尖端组装了单根碳纳米管,在真空环境下对比测量了单根碳纳米管蒸镀低逸出功材料HfC前后场致发射电流曲线和电流噪声的特点。证明了HfC蒸镀在碳纳米管上能够显著降低发射体的逸出功,减少电流噪声,并且观察到单根碳纳米管蒸镀了HfC后7μA左右的稳定电流发射。通过分析电流噪声,认为碳纳米管场致发射噪声主要来自吸附气体的频繁吸附和脱附。在低电流下,空间电离的离子轰击发射体表面,对吸附状态的影响占主导地位。当单根碳纳米管的场致发射电流超过1μA量级以后,碳纳米管表面温度快速升高,温度对气体吸附的影响占主导地位,吸附的气体分子逐渐脱附后,电流噪声开始降低。
A two-dimensional electrophoresis method was used to assemble a single carbon nanotube at the tip of the AFM. The characteristics of the field emission current curve and the current noise before and after the single-walled carbon nanotube evaporation HfC were measured in a vacuum environment . It is proved that HfC evaporation on carbon nanotubes can significantly reduce the work function of the emitter and reduce the current noise, and the steady current emission of about 7 μA after single-walled carbon nanotubes evaporation is observed. By analyzing the current noise, it is considered that the field emission of carbon nanotubes is mainly caused by the frequent adsorption and desorption of adsorbed gas. At low currents, ionized ions bombard the surface of the emitter, affecting the state of adsorption dominance. When the field emission current of a single carbon nanotube exceeds 1 μA, the surface temperature of the carbon nanotubes rapidly increases, and the influence of temperature on the gas adsorption dominates. After the adsorbed gas molecules gradually desorb, the current noise starts to decrease.