Stabilities, Electronic and Optical Properties of SnSe2(1‿i>x)S2x Alloys: A First-Principles Study

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• 作者：Yucheng Huang ; Xi Chen ; Danmei Zhou ; Hai Liu ; Chan Wang ; Jinyan Du ; Lixin Ning ; Sufan Wang
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：March 17, 2016
• 年：2016
• 卷：120
• 期：10
• 页码：5839-5847
• 全文大小：656K
• ISSN：1932-7455

文摘

First-principles investigations are performed on the stabilities and electronic and optical properties of SnSe_2(1–x)S_2x (x = 0.0625, 0.25, 0.5, 0.625, 0.8125, and 1.0) monolayer alloys by using density functional theory calculations. It is found that, above a critical temperature of 702 K, the mixing of SnSe₂ and SnS₂ is likely to form random alloys. The calculated negative substitution energy of S at the Se site of SnSe₂ suggests an alternative strategy for the synthesis of the alloys, i.e., by the substitution of S for Se in SnSe₂ monolayers. It is also shown that, due to the lattice mismatch and the pronounced charge transfer between SnSe₂ and SnS₂, the band-gap values of the alloys deviate strongly from the concentration-averaged values of the constituents. Moreover, the dielectric functions of the alloys are determined to be anisotropic, with optical properties along the xy plane being more susceptible to the S content than those along the z direction, and the alloying enhances the absorption strength in the visible spectral region. We hope that these insights will be useful for future applications of SnSe_2(1–x)S_2x alloys.