應用第一原理計算研究氮化硼摻雜之石墨烯

Abstract

在石墨烯中置換型摻雜氮化硼是一個有效打開能隙的方法，在此論文中，運用第一原理計算探討氮化硼區域在石墨烯中的形成以及系統的電子結構。計算結果顯示出氮化硼在石墨烯中傾向形成緊密的六角形與區域，並且發現在固定的石墨烯晶胞大小下摻雜固定濃度的氮化硼，系統若具有較大數目的硼–氮鍵、碳–碳鍵以及較低的庫倫勢能，則系統越穩定。在電子結構的計算結果中，發現若越大的氮化硼區域被摻雜在石墨烯中，則系統具有較大的能隙，且在低摻雜濃度下(~35%)，能隙的大小隨著摻雜濃度的增加而線性增加。因此，在石墨烯中摻雜不同大小和形狀的氮化硼區域為一個有效調控能隙的方法，這可以應用在以石墨烯為導電材料的電晶體中。

Boron-nitride (BN) substitutional doping is an efficient way to open a band gap in graphene. In this thesis, the formation of BN domains in graphene and their electronic structures are investigated by performing first-principles calculations. It is found that the BN-doped graphene system tends to have compact BN hexagons and domains. It is also concluded that at a certain doping level in a fixed supercell, higher numbers of B-N bonds and C-C bonds, and lower Coulomb potential energies will result in more stable monolayer boron-nitride-hybridized graphene (h-BNC) systems. In the examination of electronic structures, it is found that larger sizes of BN domains doped into graphene will induce wider band gaps and that the band gap value increases linearly with the BN concentration at low doping levels (~35%). Therefore, patching different sizes and shapes of BN domains inside graphene provides an effective way to tune band gaps for fabricating next-generation electronic devices.