利用第一原理計算方法探討碳相關之奈米材料之場發射特性(2/2)

Abstract

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，其表面吸附子(adsorbates) 與奈米碳管 之電子結構變化。並探討物理吸附及化學吸附對於其電子結構之影嚮。其結果可解釋實驗上，為何水分子會改善場發射之效率，而氧氣會使場發射之效率變差等等。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，並且有兩篇正在 Applied surface science及Nanotechnology 審查中。

The effective workfunctions of single-walled carbon nanotubes (5,5) (SWNTs) with various geometries and adsorbates under external electric field have been calculated by the ab initio plane-wave, pseudopotential method. In addition, the effects of participation of foreign adsorbates on the nanotube surface both physically and chemically on the variations of workfunctions have also been studied. In the physisorption process, the electrostatic interaction between adsorbates and nanotubes plays an important role under external electric field. In the chemisorption process, the variations of effective workfunctions can be understood in terms of the surface dipole of the terminated bond due to the different electronegativity between nanotubes and adsorbates.