缺陷对单层MoS_2电子结构的影响

为了研究缺陷对单层MoS_2的电子结构,本文基于密度泛函理论框架下的第一性原理,采用数值基组的方法计算了MoS_2的Mo位缺陷、S位缺陷的能带结构和态密度.结果发现:Mo位缺陷、S位缺陷的MoS_2的能带结构中的价带顶与导带底都在Q点,为直接带隙材料;其中Mo位缺陷体的禁带区域都出现5条新能级,S位缺陷体的禁带区域出现了3条新能级;缺陷体能带结构的能量下降与体系中未成键的电子有关.对于态密度而言,Mo位缺陷体的费米能级处出现了峰值,表明Mo位缺陷会对其光电性质带来影响.同时分析电荷分布发现,Mo缺陷周围存在着负电荷聚集的现象,S缺陷周围存在正电荷聚集的现象.

Effect of defects on the electronic structure of monolayer MoS2

To study the effect of defect on the electronic structure of monolayer MoS2, the band structures and density of states of Mo position defect and S position defect of monolayer MoS2 are calculated, respectively, using first-principles density functional theory based on the numeric basis sets method in this paper. Calculations indicate that the defect systems are direct band structure materials because of the top of the valence band and the bottom of the conduction band are located in Q point. There are 5 new levels in the band gap region of the Mo position defect system, and 3 new levels of the band gap region of the S position defect systems. Conduction and valence bands shift to lower energy region because of the related free electrons. For density of states, it shows that the Mo position defect system will affect the photoelectric properties for appearing the peak value at the Fermi level. We found a negative charge accumulation around in the Mo position defect system, and a positive charge accumulation around in the S position defect system.