Bilayer (BL) two-dimensional transition metal dichalcogenides (TMDs) exhibit excellent properties in carrier mobility , state density, and room temperature stability, which attract considerable attention. However, previous efforts on synthesis BL TMDs have lacked homogeneity and control over the number of layers. Here, we demonstrate an effective and controllable approach to synthesize highly uniform 3R phase BL MoS 2 on a c-plane sapphire substrate . The number of MoS 2 layer can be controlled by adjusting the confinement distance, sapphire step height (annealing temperature), and growth temperature. These influencing factors have been thoroughly investigated. Raman and PL analyses demonstrate bilayer properties and remarkable uniformity. SHG and HAADF-STEM measurements reveal 3R stacking structure of BL MoS 2 . Furthermore, field-effect-transistor (FET) devices fabricated using BL MoS 2 domains exhibit high carrier mobility and on/off ratio. This work provides an efficient method for layer-controlled MoS 2 growth and offers new insights into the growth mechanism of BL MoS 2 .
Yang Yang,Liang Qing-Rong,Zhu Chun-Li,Zheng Guo-Zhong,Zhang Jian,Zheng Shou-Jun,Lin Yung-Chang,Zheng De-Zhi,Zhou Jia-Dong
Van der Waals coupling with different stacking configurations can significantly affect the optical and electronic properties of ultrathin two-dimensional (2D) materials, which is an effective way to tune device performance. Herein, we report a salt-assisted chemical vapor deposition method for the synthesis of bilayer V-doped MoS 2 with 2H and 3R phases, which are demonstrated by the second harmonic generation and scanning transmission electron microscopy. Notably, the mobility of the 3R phase V-doped MoS 2 is 6.2% higher than that of the 2H phase. Through first-principles calculations, we further reveal that this particular behavior is attributed to the stronger interlayer coupling of 3R compared to the 2H stacking configuration. This research can be further generalized to other transition metal chalcogenides and will contribute to the development of electronic devices based on 2D materials in the future.
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