Fast growth of large-grain and continuous MoS2 films through a self-capping vapor-liquid-solid method
- Citation:
- Chang, M-C, Ho P-H, Tseng M-F, Lin F-Y, Hou C-H, Lin I-K, Wang H, Huang P-P, Chiang C-H, Yang Y-C, Wang I-T, Du H-Y, Wen C-Y, Shyue J-J, Chen C-W, Chen K-H, Chiu P-W, Chen L-C. 2020. Fast growth of large-grain and continuous MoS2 films through a self-capping vapor-liquid-solid method, 2020. 11(1):3682.
Abstract:
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 MoS2 films. An intermediate liquid phase-Na2Mo2O7 is formed through a eutectic reaction of MoO3 and NaF, followed by being sulfurized into MoS2. The as-formed MoS2 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 cm2 V−1 s−1 for the mono and bilayer regions) and on/off ratio (1 ~ 5 × 108) across a 1.5 cm × 1.5 cm region.
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