锯齿型石墨烯纳米带的能带研究

运用π电子紧束缚模型,具体研究了锯齿型石墨烯纳米带(ZGNRs)的边界结构对能带,特别是费米面附近的导带和价带电子的影响.计算了七种不同边界结构的ZGNRs的能带色散关系及费米面附近价带电子在原胞中各原子上的分布情况.计算结果表明:两边界都无悬挂原子的NN-ZGNRs,只有一边界有悬挂原子的DN-ZGNRs,两边界都有五边形环的SPP-ZGNRs和ASPP-ZGNRs为金属性.两边界都有悬挂原子的DD-ZGNRs,一边界为五边形环另一边界无悬挂原子的PN-ZGNRs和一边界为五边形环另一边界有悬挂原子的P 关键词： 锯齿型石墨烯纳米带 紧束缚模型 电子密度分布 缺陷结构

Band structures of zigzag graphene nanoribbons

Based on the π-electron tight-binding model, for zigzag graphene nanoribbons(ZGNRs) the influence of boundary structure on band structure, specially the electrons of the valence band and the conductor band near the Fermi level, are studied in detail. We investigate the band structures and the distributions of electrons of different atoms in a unit cell of the valence band near the Fermi level of ZGNRs with seven reasonable boundary structures. We find NN-ZGNRs with no dangling atoms on both edges, DN-ZGNRs with dangling atoms only on one edge, SPP-ZGNRs and ASPP-ZGNRs each with pentagons on both two edges and being metallic, DD-ZGNRs with dangling atoms on both two edges, PN-ZGNRs each with a defective structure of pentagons on one edge and no dangling atoms on the other edge, PD-ZGNRs with a pentagon on one edge and dangling atoms on the other edge being semiconducting, and the energy gap being inversely proportional to the width of nanoribbons. But for DD-ZGNRs and PD-ZGNRs, the energy gaps quickly reduce to zero with the increase of width; for PN-ZGNRs, the energy gaps decrease exponentially to a limited value of 0.154 eV. It is found that different boundary structures have different effects on the distribution of electrons in the valence band near the Fermi level. And the probability for electrons staying in the atoms on two edges of nanoribbons is relatively large.