期刊
APPLIED SURFACE SCIENCE
卷 504, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.apsusc.2019.144371
关键词
WS2(1-x)Te2x alloy; CVD method; Band structure; Phase transition; Doping behavior
类别
资金
- Natural Science Foundation of China [NSFC 61704129, 21701129]
- Natural Science Foundation of Shaanxi Province [2017JQ5015, 2018JQ2014]
Two-dimensional (2D) transition-metal tellurides have recently emerged as a nontrivial material for novel physical properties. Alloying tellurium with other 2D sulfides/selenides will give rise to new interesting phenomena and find broad opportunities in device applications. However, the growth of Te-based alloys to date is largely limited. Here, we demonstrate a chemical vapour deposition (CVD) method to synthesize monolayer WS2(1-x)Te2x alloys with a wide range of Te composition (x = 0-1.0) via modulating the concentration of hydrogen gas. The substitutional Te-doping at chalcogen sites would lead to a structural phase transition from semiconducting 2H to semimetallic 1T' phase at high Te ratio (>= 50%). Accordingly, the optical band gaps of the alloys have redshifted from 1.97 to 1.67 eV in 2H phase and directly quenched in 1T' phase. Besides, Te dopants were microscopically observed a random distribution within 2H structure, while S atoms displayed the anisotropic ordering in 1T' phase. This alloy engineering can also effectively modulate the conductivity behavior of devices. Our work provides a facile method to control the composition and phase in alloying process, which expands the library of 2D materials and inspires the fundamental studies for nanoelectronics and nanophotonics applications.
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