In Case You Missed It: 'Polarization Switching and Electrical Control of Interlayer Excitons in Two-Dimensional van der Waals Heterostructures'

摘要

The long-lived interlayer excitons in van der Waals heterostructures based on transition-metal dichalcogenides, together with unique spin-valley physics, make them promising for next-generation photonic and valleytronic devices. Although the emission characteristics of interlayer excitons have been studied, efficient manipulation of their valley states, a necessary requirement for information encoding, is still lacking. Here, the authors demonstrate comprehensive electrical control of interlayer excitons in a MoSe_2/WSe_2 heterostructure. Encapsulation of the well-aligned stack with hexagonal boron nitride (h-BN) permits the resolution of two separate narrow interlayer transitions with opposite helicities under circularly polarized excitation, either preserving or reversing the polarization of incoming light. By electrically controlling their relative intensities, the authors realize a polarization switch with tunable emission intensity and wavelength. Finally, large g-factors of these two transitions on application of an external magnetic field are observed. These results are interpreted within the picture of moire-induced brightening of forbidden optical transitions. The ability to control the polarization of interlayer excitons is a step toward the manipulation of the valley degree of freedom in realistic device applications. [Nature Photonics, January 2019).