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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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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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.
Alloy , TMD Alloys , 2D materials , Monolayer , Semiconductors
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: