title: Order-disorder phase transitions in the two-dimensional semiconducting transition metal dichalcogenide alloys Mo(1-x)W(x)X₂ (X = S, Se, and Te).
abstract: A combination of density functional theory, an empirical model, and Monte Carlo simulations is used to shed light on the evolution of the atomic distribution in the two-dimensional semiconducting transition metal dichalcogenide alloys Mo(1-x)W(x)X2 (X = S, Se, and Te) as a function of the W concentration and temperature. Both random and ordered phases are discovered and the origin of the phase transitions is clarified. While the empirical model predicts at x = 1/3 and 2/3 ordered alloys, Monte Carlo simulations suggest that they only exist at low temperature due to a small energetic preference of Mo-X-W over Mo-X-Mo and W-X-W interactions, explaining the experimental observation of random alloy Mo(1-x)W(x)S2. Negative formation energies point to a high miscibility. Tunability of the band edges and band gaps by alteration of the W concentration gives rise to a broad range of applications.
authors.affiliation: PSE Division, KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Li-Yong
authors.initials: LY
authors.lastname: Gan
authors.affiliation: PSE Division, KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Qingyun
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Physics, South China University of Technology, Guangzhou 510640, People's Republic of China.
authors.forename: Yu-Jun
authors.initials: YJ
authors.lastname: Zhao
authors.affiliation: PSE Division, KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Yingchun
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: PSE Division, KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Udo
authors.initials: U
authors.lastname: Schwingenschlögl