摘要:
采用基于密度泛函理论的第一性原理方法,对二维BC2N薄片的结构稳定性和电子性质进行了系统的研究.计算了BC2N化合物16种可能的二维单层结构.对它们的能带结构分析发现,对称性最高的构型与石墨烯一样是一种半金属,而其他二维结构则为有不同带隙的半导体,其中最稳定的构型是带隙值为1.63eV的直接带隙半导体.对最稳定构型的差分电荷密度分析和Bader分析发现：在最稳定的构型中,C—C键、C—N键、C—B键和B—N键主要以共价键的形式呈现,也具有比较明显的离子性.在应力作用下最稳定构型的单层BC2N的带隙宽度会发生变化,压缩时带隙变宽,而拉伸时带隙变窄,但仍然为直接带隙半导体.
Abstract:
The structural stability and the electronic properties of two-dimensional monolayer BC2N are studied by employing the first principles method based on the density functional theory.16 polymorphic structures of monolayer BC2N are calculated.Analysis of the 16 band structures suggests that the structure with the highest symmetry is of a semimetal which is the same as graphene.All the other structures are of semiconductors with different band gaps,of which the most stable structure is of semiconductor with a direct gap of 1.63 eV.Based on the deformation charge density and the Bader analysis,the bonds C—C,C—N,C—B,and B—N in the most stable monolayer BC2N are mainly covalent,however,they present also significant ionic behaviors.Exerting a stress on the monolayer BC2N sheet changes the band gap,showing that the band gap increases during the compression while decreases during the stretch,and the system keeps a direct semiconductor.
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