title: Two-dimensional molybdenum tungsten diselenide alloys: photoluminescence, Raman scattering, and electrical transport.
abstract: Two-dimensional transition-metal dichalcogenide alloys have attracted intense attention due to their tunable band gaps. In the present work, photoluminescence, Raman scattering, and electrical transport properties of monolayer and few-layer molybdenum tungsten diselenide alloys (Mo1-xWxSe2, 0 ≤ x ≤ 1) are systematically investigated. The strong photoluminescence emissions from Mo1-xWxSe2 monolayers indicate composition-tunable direct band gaps (from 1.56 to 1.65 eV), while weak and broad emissions from the bilayers indicate indirect band gaps. The first-order Raman modes are assigned by polarized Raman spectroscopy. Second-order Raman modes are assigned according to its frequencies. As composition changes in Mo1-xWxSe2 monolayers and few layers, the out-of-plane A1g mode showed one-mode behavior, while B2g(1) (only observed in few layers), in-plane E2g(1), and all observed second-order Raman modes showed two-mode behaviors. Electrical transport measurement revealed n-type semiconducting transport behavior with a high on/off ratio (>10(5)) for Mo1-xWxSe2 monolayers.
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology , Beijing 100190, People's Republic of China.
authors.forename: Mei
authors.initials: M
authors.lastname: Zhang
authors.forename: Juanxia
authors.initials: J
authors.lastname: Wu
authors.forename: Yiming
authors.initials: Y
authors.lastname: Zhu
authors.forename: Dumitru O
authors.initials: DO
authors.lastname: Dumcenco
authors.forename: Jinhua
authors.initials: J
authors.lastname: Hong
authors.forename: Nannan
authors.initials: N
authors.lastname: Mao
authors.forename: Shibin
authors.initials: S
authors.lastname: Deng
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Chen
authors.forename: Yanlian
authors.initials: Y
authors.lastname: Yang
authors.forename: Chuanhong
authors.initials: C
authors.lastname: Jin
authors.forename: Sunil H
authors.initials: SH
authors.lastname: Chaki
authors.forename: Ying-Sheng
authors.initials: YS
authors.lastname: Huang
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.forename: Liming
authors.initials: L
authors.lastname: Xie