界面势垒对碳纳米管场发射特性的影响
Effect of interface barrier on carbon nanotube field emission property
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摘要: 以界面势垒对碳纳米管(CNT)场发射的影响为研究目的，在硅衬底上引进很薄的二氧化硅层，以二氧化硅层作为绝缘势垒，然后在二氧化硅界面层上直接生长CNT，来研究二氧化硅绝缘势垒层对CNT场发射的影响。场发射结果为：Fowler-Nordheim(F-N)曲线分为两部分,高电场下偏离F-N曲线并趋于饱和。在双势垒模型的基础上，从电场在两势垒上的分布不同及电子在两势垒上的隧穿几率不同，理论上分析了界面势垒对场发射的影响：低电场下电子在界面势垒的隧穿几率大于在表面势垒的隧穿几率，界面势垒对场发射不起阻碍作用，场发射遵守F-N规律；高电场下电子在界面势垒的隧穿几率小于在表面势垒的隧穿几率，场发射偏离F-N规律。理论对实验结果进行了合理的解释。Abstract: Carbon nanotube was deposited on Si substrate which was intentionally covered with a certain thickness SiO2 layer as the interface barrier. A doublepotential barrier model was proposed and the tunneling probability of the two barriers in the external electric field was qualitatively discussed. The two variable tunneling probabilities of interface barrier and surface barrier are the reason of the nonlinearity of the Fowler-Nordheim(F-N) plots. The plots follow the F-N law in low electric field because the tunneling probability of interface barrier is larger than that of surface barrier. The plots do not follow the F-N law in high electric field because the tunneling probability of surface barrier is higher．
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