石墨烯纳米带能带结构及透射特性的扭曲效应

摘要

利用基于密度泛函理论的第一性原理方法,系统研究了石墨烯纳米带(GNRs)电学性质的扭曲效应。结果表明：锯齿型石墨纳米带(ZGNRs)的带隙对扭曲形变最不敏感,在扭曲过程中几乎保持金属性不变,其次是W=3p−1型扶手椅型石墨烯纳米带(AGNRs),扭曲时带隙也只有较小的变化。 W=3p+1型AGNRs的带隙对扭曲最为敏感,扭曲发生时,呈现宽带隙半导体、中等带隙半导体、准金属、金属的变化,其次是W =3p型AGNRs,扭曲时带隙变化也较为明显。换言之, GNRs在无扭曲时带隙越大,扭曲发生后带隙变化(变小)越明显。对于整个电子结构及透射系数来说,扭曲对AGNRs影响较大,而对ZGNRs的影响相对小些。研究表明：由于石墨烯容易变形,其相关电子器件的设计必须适当考虑扭曲对电学性质的影响。%By using the first-principles method based on the density-functional theory, twisting-deformation-dependent electrical charac-teristics of graphene nanoribbons (GNRs) are studied systematically. It is shown that the energy gap of the zigzag-edge graphene nanoribbon (ZGNR) is the most insensitive to twisting deformation, and it almost keeps metallicity unchanged, next is the armchair-edge graphene nanoribbons (AGNRs) by width W=3p−1 (p is a positive integer), and its gap has only a small change when twisting deformation occurs. However, the gap of AGNR with width W =3p+1 is extremely sensitive to twisting deformation, and it can display a variation from wide-gap semiconductor to moderate-gap semiconductor, quasi-metal, and metal, next is AGNR with W=3p. In other words, the larger the band gap for GNR in the absence of twisting deformation, the more significant the change (becoming small) of its band gap with twisting deformation. Additionally, for the whole electronic structure and transmission behavior, one can find that there is a much larger influence under twisting deformation in AGNR than in ZGNR. These studies suggest that it is necessary to take the effect of twisting deformation on the electrical characteristics into account in designing GNR-based nanodevices.