He Wen, Shi Jia, Zhao Hongkang, Wang Hui, Liu Xinfeng, Shi Xinghua
School of Physics, Beijing Institute of Technology Beijing 100081 China.
Laboratory of Theoretical and Computational Nanoscience, CAS Key Laboratory for Nanosystem and Hierarchy Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Chinese Academy of Sciences Beijing 100190 China
RSC Adv. 2020 Apr 21;10(27):15702-15706. doi: 10.1039/d0ra01676d.
Band-gap engineering of molybdenum disulfide (MoS) by introducing vacancies is of particular interest owing to the potential optoelectronic applications. In this work, systematic density functional theory (DFT) calculations were carried out for few-layered 3R-MoS with different concentrations of S vacancies. All results revealed that the defect energy levels introduced on both sides of the Fermi level formed an intermediate band in the band gap. Both the edges of the intrinsic and intermediate bands of the structures with the same type of vacancies were generally closer to the Fermi level, and the gaps decreased as the number of layers increased from 2 to 4. The preferentially formed S vacancies at the top layer and the transition of defect types from point to line led to similar indirect band gaps for 2- and 4-layered 3R-MoS with a low bulk concentration (around 5%) of S vacancies. This is different from most reported results about transition metal dichalcogenide (TMD) materials that the indirect band gap decreases as the number of layers increases and the low concentrations of vacancies show negligible influence on the band gap value.
通过引入空位对二硫化钼（MoS）进行带隙工程，因其潜在的光电子应用而备受关注。在这项工作中，对具有不同浓度S空位的少层3R-MoS进行了系统的密度泛函理论（DFT）计算。所有结果表明，在费米能级两侧引入的缺陷能级在带隙中形成了一个中间带。具有相同类型空位的结构的本征带和中间带的边缘通常更靠近费米能级，并且随着层数从2增加到4，带隙减小。顶层优先形成的S空位以及缺陷类型从点到线的转变，导致具有低体浓度（约5%）S空位的2层和4层3R-MoS具有相似的间接带隙。这与大多数关于过渡金属二硫属化物（TMD）材料的报道结果不同，即间接带隙随着层数的增加而减小，并且低浓度的空位对带隙值的影响可忽略不计。
