陳俊維2006-07-252018-06-282006-07-252018-06-282003http://ntur.lib.ntu.edu.tw//handle/246246/12447本計劃主要是利用第一原理之計算方法，探討奈米碳管在電場的作用下，其奈米碳管表面電子結構變化。並探討電場滲透效應(field penetration effect)對奈米碳管表面功函數變化之 影響。發現電場滲透效應會降低奈米碳管之功函數，增加其場發射之效率。其結果可解釋為奈米碳管尖端為類似半導體之模型。。此研究結果以於Diamond and Related materials 12, 565, 2003 及即將有另外一篇將於Diamond and Related materials(2004)發表，並且有一篇正在 Applied surface science 審查中。Field penetration induced charge redistribution effects on the field emission properties of carbon nanotubes have been studied by the first-principles calculations. It is found that the carbon nanotube is polarized under external electric field leading to charge redistribution. The resulting band bending induced by field penetration into the nanotube tip surface can further reduce the effective workfunction of carbon nanotubes (CNTs). The magnitude of redistributed charge ∆Q is found nearly linear to the applied external field strengths. In addition, we found that capped (9,0) zigzag nanotube demonstrates better field emission properties than the capped (5,5) nanotube due to that the charge redistribution of π electrons along the zigzag-like tube axis is easier than the armchair-like tube. The density of states (DOS) of the capped region of the nanotube is found to be enhanced with a value of 30 % higher than that of the sidewall part for the capped (5,5) nanotube and 40% for the capped (9,0) nanotube under the electric field of 0.33 V/A. Such enhancements of DOS at the carbon nanotube tip show that electrons near the Fermi level will emit more easily due to the change of surface band structure resulted from the field penetration in a high field.application/pdf65686 bytesapplication/pdfzh-TW國立臺灣大學材料科學與工程學研究所reporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/12447/1/912216E002039.pdf