Spin-Orbit Engineering in Transition Metal Dichalcogenide Alloy Monolayers
Binary transition metal dichalcogenide monolayers share common properties such as a direct optical bandgap, spin-orbit splittings of hundreds of meV, light–matter interaction dominated by robust excitons and coupled spin-valley states. Here we demonstrate spin-orbit-engineering in Mo[(1-x)]WxSe2 alloy monolayers for optoelectronics and applications based on spin- and valley-control. We probe the impact of the tuning of the conduction band spin-orbit spin-splitting on the bright versus dark exciton population. For MoSe2 monolayers, the photoluminescence intensity decreases as a function of temperature by an order of magnitude (4–300 K), whereas for WSe2 we measure surprisingly an order of magnitude increase. The ternary material shows a trend between these two extreme behaviors. We also show a non-linear increase of the valley polarization as a function of tungsten concentration, where 40% tungsten incorporation is sufficient to achieve valley polarization as high as in binary WSe2.
- Author (aut): Wang, Gang
- Author (aut): Robert, Cedric
- Author (aut): Tuna, Aslihan
- Author (aut): Chen, Bin
- Author (aut): Yang, Sijie
- Author (aut): Alamdari, Sarah
- Author (aut): Gerber, Iann C.
- Author (aut): Amand, Thierry
- Author (aut): Marie, Xavier
- Author (aut): Tongay, Sefaattin
- Author (aut): Urbaszek, Bernhard
- Contributor (ctb): Ira A. Fulton Schools of Engineering