Park Noejung, Han Seungwu, Ihm Jisoon
School of Physics, Seoul National University, Seoul 151-742, Korea.
J Nanosci Nanotechnol. 2003 Feb-Apr;3(1-2):179-83. doi: 10.1166/jnn.2003.207.
Field emission properties of carbon nanotubes coated with a single layer of boron nitride are calculated using the first-principles pseudopotential method. At lower bias voltage, the emission current of the coated nanotube is comparable to that of the bare carbon nanotube and is dominated by the contribution from localized states at the tip of the tube. At higher voltage, newly generated hybridized states between the carbon nanotube tip and the even-membered boron nitride rings contribute significantly to the emission current because they experience a low tunneling barrier compared with the bare carbon nanotube case. Our results suggest that the insulator coating can, besides protecting the nanotube tip from the attack of gas molecules, substantially enhance the field emission current.
采用第一性原理赝势方法计算了单层氮化硼包覆的碳纳米管的场发射特性。在较低偏置电压下，包覆纳米管的发射电流与裸碳纳米管的发射电流相当，且主要由管尖端局域态的贡献主导。在较高电压下，碳纳米管尖端与偶数元氮化硼环之间新产生的杂化态对发射电流有显著贡献，因为与裸碳纳米管的情况相比，它们经历的隧穿势垒较低。我们的结果表明，绝缘体涂层除了能保护纳米管尖端免受气体分子的侵蚀外，还能大幅增强场发射电流。
