title: Chemical Vapor Deposition of Monolayer Mo(1-x)W(x)S2 Crystals with Tunable Band Gaps.
abstract: Band gap engineering of monolayer transition metal dichalcogenides, such as MoS2 and WS2, is essential for the applications of the two-dimensional (2D) crystals in electronic and optoelectronic devices. Although it is known that chemical mixture can evidently change the band gaps of alloyed Mo(1-x)W(x)S2 crystals, the successful growth of Mo(1-x)W(x)S2 monolayers with tunable Mo/W ratios has not been realized by conventional chemical vapor deposition. Herein, we developed a low-pressure chemical vapor deposition (LP-CVD) method to grow monolayer Mo(1-x)W(x)S2 (x = 0-1) 2D crystals with a wide range of Mo/W ratios. Raman spectroscopy and high-resolution transmission electron microscopy demonstrate the homogeneous mixture of Mo and W in the 2D alloys. Photoluminescence measurements show that the optical band gaps of the monolayer Mo(1-x)W(x)S2 crystals strongly depend on the Mo/W ratios and continuously tunable band gap can be achieved by controlling the W or Mo portion by the LP-CVD.
authors.affiliation: Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Ziqian
authors.initials: Z
authors.lastname: Wang
authors.affiliation: WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Pan
authors.initials: P
authors.lastname: Liu
authors.affiliation: WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.|CREST, JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Department of Mechanical and Aerospace Engineering, School of Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR.
authors.forename: Shoucong
authors.initials: S
authors.lastname: Ning
authors.affiliation: WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Yongwen
authors.initials: Y
authors.lastname: Tan
authors.affiliation: WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.|CREST, JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fujita
authors.affiliation: WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.|CREST, JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Hirata
authors.affiliation: Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8577, Japan.|WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.|CREST, JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Mingwei
authors.initials: M
authors.lastname: Chen