Control of valley-polarized exciton currents in 2D heterostructures*

Valleytronics is an alternative to charge-based electronics aiming at encoding data in the valley degree of freedom, which could enable new paradigms for computing devices. Transition metal dichalcogenides (TMDCs) are an ideal platform for this due to the combination of unique spin–valley physics and direct bandgap, allowing optical initialization and readout of the valley state. Recent developments in the control of interlayer excitons in heterostructures of these materials offer an effective way to realize valley-optoelectronic devices [1]. Here, we show the generation and transport over mesoscopic distances of valley-polarized excitons in a device based on a type-II TMDC heterostructure. Engineering of the interlayer coupling results in enhanced diffusion of valley-polarized excitons, which can be controlled and switched electrically [2]. Furthermore, using electrostatic traps we can increase the exciton concentration by an order of magnitude, reaching densities higher than 10¹² cm^-2, a promising approach to obtain coherent quantum states of excitons.

[1] Ciarrocchi*, Unuchek* et al. Nat. Photon., 13, 2, (2019)
[2] Unuchek*, Ciarrocchi* et al. Nat. Nanotechnol. (2019)