Fast growth of large-grain and continuous MoS2 films through a self-capping vapor-liquid-solid method
Ming-Chiang Chang, Po‐Hsun Ho, Mao-Feng Tseng, Fangyuan Lin, Cheng‐Hung Hou, I-Kuan Lin, Hsin Wang, Pin-Pin Huang, C. C. Chiang, Yueh-Chiang Yang, I‐Ta Wang, He‐Yun Du, Cheng‐Yen Wen, Jing‐Jong Shyue, Chun‐Wei Chen, Kuei‐Hsien Chen, Po‐Wen Chiu, Li–Chyong Chen
Abstract
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 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.