Plasma-assisted Selenization of Monolayer MoS₂ to form Janus MoSSe for High-Yield Production

Paul Albert Sino^1*, Lee Ling², Feng-Chuan Chuang^1,3,4, Yu-Lun Chueh^1,2,5

¹Department of Physics, National Sun Yat-sen University, Kaohsiung City, Taiwan
²Department of Material Science and Engineering, National Tsing-Hua University, Hsinchu City, Taiwan
³Physics Division, National Center for Theoretical Sciences, Hsinchu City, Taiwan
⁴Department of Physics, National Tsing-Hua University, Hsinchu City, Taiwan
⁵Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing-Hua University, Hsinchu City, Taiwan

* Presenter:Paul Albert Sino, email:plsino@g-mail.nsysu.edu.tw

Two-dimensional (2D) materials with asymmetric structure like Janus Transition Metal Dichalcogenides (TMDs) exhibit intriguing electronic and optical properties which can be used for novel electronic and optoelectronic devices application. However, the synthesis of Janus TMDs still faces a lot of challenges and the fabrication technology needs further improvement. Here, we report a top-down method for high-yield production of Janus monolayer MoSSe. In particular, we replace the top S atom with Se by controlled plasma-assisted selenization of monolayer MoS₂. Based on the Raman Spectroscopy results, all of the characterized monolayer MoS₂ triangles have been transformed to Janus MoSSe. We confirmed the Janus structure of MoSSe by high-resolution transmission electron microscopy (HRTEM), energy-dependent X-ray photoelectron spectroscopy (XPS), and Density Functional Theory (DFT) calculations. The method provides an avenue towards high-yield production and full exploration of Janus TMDs.

Keywords: Janus MoSSe, plasma, selenization, high-yield, TMDs