Synthesis of component-controllable monolayer Mo x W (1− x ) S 2 y Se 2(1− y ) alloys with continuously tunable band gap and carrier type

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Date
2023-11-24
Authors
Li, You
Wang, Kangkang
Wang, Yiwen
Qian, Ziyue
Huang, Wenbin
Wang, Junqi
Yang, Qichao
Wang, Honggang
Liao, Junyi
Hussain, Sabir
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Royal Society of Chemistry
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Abstract
Alloying can effectively modify electronic and optical properties of two-dimensional (2D) transition metal dichalcogenides (TMDs). However, efficient and simple methods to synthesize atomically thin TMD alloys need to be further developed. In this study, we synthesized 25 monolayer MoxW(1−x)S2ySe2(1−y) alloys by using a new liquid phase edge epitaxy (LPEE) growth method with high controllability. This straightforward approach can be used to obtain monolayer materials and operates on a self-limiting growth mechanism. The process allows the liquid solution to come into contact with the two-dimensional grains only at their edges, resulting in epitaxy confined only along the in-plane direction, which produces exclusively monolayer epitaxy. By controlling the weight ratio of MoS2/WSe2 (MoSe2/WS2), 25 monolayer MoxW(1−x)S2ySe2(1−y) alloys with different atomic ratios can be obtained on sapphire substrates, with band gap ranging from WS2 (1.55 eV) to MoSe2 (1.99 eV) and a continuously broad spectrum ranging from 623 nm to 800 nm. By adjusting the alloy composition, the carrier type and carrier mobility of alloy-based field-effect transistors can be modulated. In particular, the adjustable conductivity of MoxW(1−x)S2ySe2(1−y) alloys from n-type to bipolar type is achieved for the first time. This general synthetic strategy provides a foundation for the development of monolayer TMD alloys with multiple components and various 2D materials.
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Alloy , TMD Alloys , 2D materials , Monolayer , Semiconductors
Citation
Li, Y., Wang, K., Wang, Y., Qian, Z., Huang, W., Wang, J., Yang, Q., Wang, H., Liao, J., Hussain, S., Xie, L. and Qi, J. (2023) ‘Synthesis of component-controllable monolayer Mo x W (1− x ) S 2 y Se 2(1− y ) alloys with continuously tunable band gap and carrier type’, RSC Advances, 13(49), pp. 34464–34474. Available at: https://doi.org/10.1039/D3RA07065D