Structural stability and intriguing electronic properties of two-dimensional transition metal dichalcogenide alloys
Structural stability and intriguing electronic properties of two-dimensional transition metal dichalcogenide alloys
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二维过渡金属二硫属化物合金的结构稳定性和有趣的电子性能
DOI：
10.1039/c7cp01727h
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发表时间：
2017
影响因子：
3.3
通讯作者：
Li Youyong
中科院分区：
文献类型：
--
作者：
Yuan Xiao;Yang Mingye;Wang Lu;Li Youyong
基于第一性原理计算，系统地研究了S和Se半混合的二维（2D）过渡金属二硫化物（TMD）合金的结构和电子性能。利用S和Se的化学势，构建了TMD单相和混合相的能相图。首次提出了一种新的异质层结构（Sc和Ti）和交替结构（Cr, Mn, Fe, Zr， Mo和W），它们在贫S （S的相对低化学势）和富Se （Se的相对高化学势）条件下对MSSe合金的热力学稳定，并与无序结构进行了比较。计算了这些稳定混合相的带隙、载流子有效质量和功函数。与MS2和MSe2单相合金相比，MSSe合金具有更好的电子性能，包括可调谐的带隙和功函数。重要的是，显著降低的载流子在MSSe合金中的有效质量可以诱导更高的载流子迁移率，提供更好的TMD材料在电子器件中的性能。
Based on the first-principles calculations, we systematically studied the structures and electronic properties of two-dimensional (2D) transition metal dichalcogenide (TMD) alloys with half-to-half mixing of S and Se. Using the chemical potentials of S and Se, the energetic phase diagrams for both single phases and mixed phases of TMD were constructed. A new heterolayer structure (for Sc and Ti) and alternating structure (for Cr, Mn, Fe, Zr, Mo, and W) were proposed for the first time, which were thermodynamically stable for MSSe alloys under the S-poor (relatively low chemical potential of S) and Se-rich (relatively high chemical potential of Se) conditions, and further compared with the disordered structures. Moreover, band gaps, carrier effective mass, and work functions were calculated for these stable mixed phases. Compared to the single phases of MS2 and MSe2, MSSe alloys showed superior electronic properties including tunable band gaps and work functions. Importantly, the significantly reduced effective mass of the carriers in the MSSe alloys may induce higher carrier mobility, providing better performance of TMD materials in electronic devices.