氢、氟原子边缘修饰β-GeSe纳米带的第一性原理研究

First-principles study on the edge modification ofβ-GeSe nanoribbons by H and F atoms

采用第一性原理计算方法研究了二维β相GeSe的电子结构,通过对二维单层β-GeSe剪切得到一维β-GeSe扶手椅型纳米带.研究不同带宽(N=1-5)β-GeSe扶手椅型纳米带的几何结构和电子性质,发现不同带宽纳米带能带带隙不同,带隙总体上随着带宽减小,而纳米带直接带隙半导体性质不受带宽影响.通过使用H、F原子对GeSe扶手椅型纳米带边缘修饰,H原子修饰纳米带导致能带类型从直接带隙向间接带隙的转变.在费米能级附近处F原子各轨道对价带和导带贡献比H原子各轨道贡献多,在边缘修饰中纳米带对F原子更加敏感.未修饰和使用H原子修饰纳米带在可见光范围内没有吸收峰,用F原子修饰纳米带在可见光范围内出现吸收峰.研究表明可以通过边缘修饰调控纳米带光学特性.

The electronic structure of two-dimensionalβ-phase GeSe is calculated based on first principles methods.The one-dimensionalβ-GeSe armchair-shaped nanoribbons with different bandwidths(N=1-5)are obtained by shearing two-dimensional single-layerβ-GeSe and their geometrical structures and electronic properties are studied.The band gaps of the nanobelts with different bandwidths are different.The band gap decreases with the increasing bandwidth in general,but the direct band gap semiconductor properties of the nanobelt are not affected by the bandwidth.The edges of the GeSe armchair-type nanoribbons are modified by H and F atoms.The modification by H atoms results in the transition of the energy band type from direct band gap to indirect band gap.Near the Fermi level,the orbitals of F atoms contribute more to the valence band and conduction band than those of H atoms.Nanobelts are more sensitive to F atoms in the edge modification.The unmodified and H atoms modifying nanobelts have no absorption peaks in the visible light range,but those modified with F atoms have absorption peaks in the visible light range.The results show that the optical properties of nanoribbons can be regulated by edge modification.