边缘修饰对锗烯纳米带电子结构的影响

Influence of Edge Modification on the Electronic Structure of Germanene Nanoribbons

本工作利用第一性原理研究了氢化效应对扶手椅型锗烯纳米带(AGeNRs)几何结构和电子结构的影响,分别计算了几何结构与稳定性、能带结构以及态密度,研究了形成能和能带结构随各种带宽度函数的变化。通过增加带的宽度,AGeNRs的带隙尺寸根据三种不同的趋势减小。基于这些趋势,可以将其分为三类,分别命名为N=3P、N=3P+1、N=3P+2,N是宽度上的锗原子数,P是整数。研究表明,裸露边缘的AGeNRs稳定性较低,氢化处理可以提高纳米带的稳定性,其中双氢化结构的稳定性最高。其次,边缘利用H原子进行修饰后,电荷密度发生转移,整个材料的电子和光学特性发生变化,说明边缘效应影响其电学和光学性质。对于裸露边缘和单氢化方式,其带隙符合N=3P+2>N=3P>N=3P+1;而对于双氢化处理和单氢化-双氢化的混合结构,其带隙符合N=3P>N=3P+1>N=3P+2。由于纳米带都是直接带隙,可以推测此类AGeNRs可能适用于光学领域,而且其电子和光学性质可以通过纳米带宽度以及氢化方式在很宽的范围内进行调节。

In this work,first-principles calculations were used to study the effect of hydrogenation on the geometric structure and electronic structure of armchair germanene nanoribbons(AGeNRs).The stability,band structures and density of states were calculated,respectively.The changes of these parameters as a function of various band widths were studied.By increasing the width of the nanoribbons,the band gap size of AGeNRs decreases according to three different trends.Based on these trends,they can be divided into three categories,named N=3P,N=3P+1,and N=3P+2,where N is the number of germanium atoms in the width,and P is an integer.The study found that the stability of the bared edges of AGeNRs is low,and the hydrogenation treatment can improve the stability of the nanoribbons,and the double hydrogenation structure has the highest stability.Secondly,after the edge is modified with H atoms,the charge density is transferred,which changes the electronic and optical properties of the materials,indicating that the edge effect affects its electrical and optical properties.For bare edges and single hydrogenation methods,the band gap conforms to N=3P+2>N=3P>N=3P+1,while for double hydrogenation and single hydrogenation-double hydrogenation mixed structures,the band gap conforms to N=3P>N=3P+1>N=3P+2.Since the nanoribbons are all direct band gaps,it could be speculated that such AGeNRs may be suitable for optical applications,and their electronic and optical properties can be adjusted in a wide range by the width of the nanoribbons and the hydrogenation method.