Voltage-controlled moiré potentials and long-range propagation of indirect excitons in a van der Waals MoSe₂/WSe₂ heterostructure

Excitonic devices based on controlled propagation of indirect excitons (IXs) are demonstrated in GaAs structures but limited to low temperatures due to low IX binding energies [1]. IXs in transition-metal dichalcogenide (TMD) heterostructures are characterized by high binding energies offering the opportunity for room-temperature operation. However, strong moiré superlattice potentials in TMD heterostructures [2,3] localize IXs, making IX propagation different in TMD and GaAs heterostructures. In earlier excitonic devices IX transport was controlled by an energy barrier to IX propagation created by the gate electrode [1]. We present a new mechanism for exciton transport control. It is based on tuning the moiré potentials by voltage to enable IX delocalization. We present the long-range IX propagation due to this mechanism. We also establish a spatial correlation between IX linewidth, energy, and luminescence intensity.

[1] A. A. High et al. Science 321, 229 (2008).

[2] F. Wu et al. PRL 118, 147401 (2017).

[3] H. Yu et al. Sci. Adv. 3, e1701696 (2017).