Fast growth of large-grain and continuous MoS2 films through a self-capping vapor-liquid-solid method

• Published in: Nature communications Vol. 11; no. 1; pp. 3682 - 9
• Main Authors: Chang, Ming-Chiang, Ho, Po-Hsun, Tseng, Mao-Feng, Lin, Fang-Yuan, Hou, Cheng-Hung, Lin, I-Kuan, Wang, Hsin, Huang, Pin-Pin, Chiang, Chun-Hao, Yang, Yueh-Chiang, Wang, I-Ta, Du, He-Yun, Wen, Cheng-Yen, Shyue, Jing-Jong, Chen, Chun-Wei, Chen, Kuei-Hsien, Chiu, Po-Wen, Chen, Li-Chyong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23.07.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 147/137; 147/3; 639/166; 639/301; 639/925; Capping; Chemical vapor deposition; Electrical engineering; Eutectic reactions; Field effect transistors; Flakes; Grain size; Humanities and Social Sciences; Liquid phases; Methods; Molybdenum disulfide; Molybdenum oxides; Molybdenum trioxide; multidisciplinary; Nucleation; Science; Science (multidisciplinary); Seeds; Semiconductor devices; Single crystals; Sodium fluoride; Substrates; Sulfur; Transistors; Transition metal compounds; Vapors
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-17517-6

Most chemical vapor deposition methods for transition metal dichalcogenides use an extremely small amount of precursor to render large single-crystal flakes, which usually causes low coverage of the materials on the substrate. In this study, a self-capping vapor-liquid-solid reaction is proposed to fabricate large-grain, continuous MoS 2 films. An intermediate liquid phase-Na 2 Mo 2 O 7 is formed through a eutectic reaction of MoO 3 and NaF, followed by being sulfurized into MoS 2 . The as-formed MoS 2 seeds function as a capping layer that reduces the nucleation density and promotes lateral growth. By tuning the driving force of the reaction, large mono/bilayer (1.1 mm/200 μm) flakes or full-coverage films (with a record-high average grain size of 450 μm) can be grown on centimeter-scale substrates. The field-effect transistors fabricated from the full-coverage films show high mobility (33 and 49 cm 2 V −1 s −1 for the mono and bilayer regions) and on/off ratio (1 ~ 5 × 10 8 ) across a 1.5 cm × 1.5 cm region. Here, the authors develop a self-capping vapour-liquid-solid reaction to fabricate large-grain continuous MoS 2 films, whereby an intermediate liquid phase-Na 2 Mo 2 O 7 is formed through a eutectic reaction of MoO 3 and NaF, followed by sulphurisation into MoS 2 .