Voltage-controlled long-range propagation of indirect excitons in MoSe₂/WSe₂ heterostructure

Indirect excitons (IXs) can form the medium for excitonic devices based on controlled propagation of excitons. Proof of principle excitonic devices are demonstrated in GaAs structures but limited to low temperatures due to the low IX binding energy [1]. IXs in transition-metal dichalcogenide (TMD) heterostructures are characterized by high binding energies offering the possibility for room-temperature operation of excitonic devices. However, IX propagation is fundamentally different between GaAs and TMD heterostructures due to the presence of moiré superlattice potentials in TMDs, reaching tens of meV [2,3] and forming an obstacle for IX propagation. We present long-range IX propagation with 1/e IX luminescence decay distances reaching 13 microns in MoSe₂/WSe₂ heterostructure despite predicted moiré potentials. We directly measure long-range IX propagation by tracing the IX luminescence through the device and control it by voltage in an excitonic transistor.
[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).