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標題: | 手性狀奈米石墨帶之電子特性 Electronic Properties of Chiral Graphene Nanoribbons |
作者: | Ching-Pai Hsu 許清白 |
指導教授: | 薛文証 |
關鍵字: | 石墨烯,奈米石墨帶,鋸齒狀,手椅狀,緊束縛法,手性狀,大鋸齒狀,能帶結構, graphene,graphene nanoribbons,zigzag,armchair,tight-binding method,chiral,sawtooth-like,band structure, |
出版年 : | 2012 |
學位: | 碩士 |
摘要: | 本論文主旨為研究準一維結構的奈米石墨帶之電子特性。首先以石墨烯為探討對象,了解到有別於傳統半導體的獨特物理性質,接著考量到石墨烯不具能隙,在往後應用於邏輯電路上將不能關斷,遂沿著石墨烯高對稱方向切劃呈帶狀,其利用量子侷限的概念是最自然且有效地製造出能隙的方法之一,基於石墨烯的蜂巢狀結構,石墨帶有兩種典型的原型,分別是鋸齒狀與手椅狀奈米石墨帶。本文理論研究奠基於緊束縛法,其顯示出石墨帶具有奇異的電子特性,例如鋸齒狀奈米石墨帶皆為金屬性,而手椅狀奈米石墨帶在寬度為N=3p+2為金屬性,其餘狀況下則出現能隙,並且有著規律性的震盪且大小與寬度呈反比。實際上,石墨烯不可能完美的切割成鋸齒或手椅方向,因此考量到鋸齒狀與手椅狀混合型式的手性狀奈米石墨帶將更貼近真實的奈米石墨帶,如此可以建立出一般性邊緣的電子能帶結構分析。除此之外,由特別的兩塊鋸齒狀奈米石墨帶以 角拼湊而成的大鋸齒狀奈米石墨帶,基於如此奇特邊緣結構會產生比典型奈米石墨帶更豐富的能隙特徵。這些數值分析結果對於日後設計石墨帶電晶體將非常具有幫助性。 The main purpose of this thesis is to investigate the electronic properties of quasi-one-dimensional graphene nanoribbons. Graphene has been shown to possess several intriguing electronic properties. However, one of the obstacles for logic applications is the absence of an energy band gap. In order to open a gap, graphene was cut into stripes of high-symmetry zigzag and armchair directions. Theoretical studies based on tight-binding method have shown remarkable electronic properties of graphene nanoribbons. For example, zigzag graphene nanoribbons are always metallic, while armchair graphene nanoribbons are metallic for N=3p+2, and semiconducting in other cases. Armchair graphene nanoribbons have an energy gap which has an oscillating behavior and proportional to the inverse width. In practice, graphene can not be cut into single perfect zigzag or armchair direction but the combination of both, which is called chiral graphene nanoribbons. Thus the band structure of any graphene nanoribbons with general edge can be described. In addition, sawtooth-like graphene nanoribbons consist of a bent angle of 120 degree between two zigzag edge segments, which induce richer band gap phenomenon than prototypical graphene nanoribbons. These numerical analyses are helpful for designing GNR transistors in the future. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/16228 |
全文授權: | 未授權 |
顯示於系所單位: | 工程科學及海洋工程學系 |
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