碳纳米管场发射烧毁机理研究

Mechanismsfor Burning Damage of Carbon Nanotube Array Thin Film in Field Emission

在碳纳米管场发射过程中,碳纳米管烧毁现象一直是影响碳纳米管场发射能力及稳定性的重要因素。目前,对碳纳米管烧毁机理研究较少。本文采用化学气相沉积原位生长技术制备了不同形貌的碳纳米管阵列。通过对不同形貌的碳纳米管场发射测试过程及碳纳米管烧毁前后形貌的研究,得出碳纳米管烧毁机理主要有三种。一是碳纳米管高度不均匀和碳纳米管本身的缺陷等原因引起了电场局域现象,这种局域场强使得碳纳米管局域温度过高而引起碳纳米管烧毁;二是碳纳米管吸附和脱附造成碳纳米管烧毁;三是碳纳米管与基片间存在较高的接触电阻而产生较高的焦耳热,使得碳纳米管烧毁。本文不仅给出了碳纳米管烧毁机理,还给出了相应的解决方案。这对碳纳米管场发射阴极的研究具有一定的意义。

Here,we addressed the mechanisms responsible for burning damage of the patterned carbon nano- tube（CNT） array thin-film, synthesized by chemical vapor depoSition on Si substrate, in field emission. The impact of non-uniformity, defects and contamination of the CNT array on the localized burning was investigated with scan- ning electron microscopy and transmission electron microscopy. The results show that the microstructures and quality of the CNT array explained the localized burning. First, large emission current easily burnt a protruding CNT be- cause of the much stronger localized field at its apex. Second, some spots were burnt by the non-uniform resistive Joule heating at the CNTs/substrate contact. Finally, various factors, including but not limited to the desorbed gases, carbon clusters, CNT＇ s wall defects and multi-walled CNTs, accounted for the ＂short-circuit＂ burning in field emis- sion. Possible solutions of the burning problems in CNT array field emission were suggested.