具有可调电学和光学性质的双层和三层Janus Ga2SSe

将二维(2D)层状材料的单层堆叠成双层或者少数层，可以很好的调节其光电性质，为该领域发展提供了新的机遇.本文采用第一性原理方法系统地研究了堆叠层数和堆叠次序对双层和三层Janus Ga₂SSe的电学和光学性质的影响.我们发现这些结构的层间距差别很大，而结合能差异却很小.尽管所有的双层和三层Janus Ga₂SSe具有间接带隙，然而其带隙值和载流子有效质量与堆叠层数和堆叠次序密切相关.此外，在Janus Ga₂SSe中，通过增加层数，可以增强其在可见光和紫外区域的吸收系数.同时，通过控制层间堆叠模式，进一步调制其吸收系数，导致在可见光和近紫外区域产生多个吸收峰.我们的结果为双层和三层Janus III族单硫化合物的可调节电学和光学性质提供了有价值的见解，这表明其可能在纳米电子和光电子器件中有着广阔的应用前景.

Bilayer and trilayer Janus Ga2SSe with tunable electronic and optical properties

The possibility of stacking monolayers into bilayer and few-layer offers new opportunities in the field of two dimensional (2D) materials. In this paper, the influence of stacking layer number and stacking configurations on the electronic and optical properties of bilayer and trilayer Janus Ga2SSe have been systematically studied by first-principles method. We demonstrate that the interlayer distance in those structures is quite different, while the binding energy difference is small. While all the bilayer and trilayer Janus Ga2SSe have indirect band gap, the band gap values and carrier effective masses are closely related to the stacking layer number and stacking configurationgs. Additionally, in the Janus Ga2SSe, by increasing the number of layers, the absorption coefficients are enhanced in the visible and ultraviolet region. Meanwhile, by controlling the stacking patterns, the absorption coefficients are further modified, leading to multiple absorption peaks generated in the visible and near ultraviolet regions. Our results provide valuable insight for the adjustable electrical and optical properties in the bilayer and trilayer Janus group-III monochalcogenides, which may have promising applications in nanoelectronic and optoelectronic devices.