Modulating optical emission from dipolar excitons in vdW heterostructures by surface acoustic waves*

Surface acoustic waves (SAW) can couple to excitons via strain fields allowing for dynamic optoelectronics. Recently, interlayer excitons with permanent out-of-plane dipole moment have been discovered in transition metal dichalcogenide heterostructures. Due to their long lifetimes, interlayer excitons are expected to interact strongly with SAW. The strain field through deformation potential or piezoelectric coupling can create a dynamic localization for excitons. In order to analyze the effects of the SAW on the properties of excitons, we fabricated a device with a MoSe₂/WSe₂ heterobilayer on a LiNbO₃ substrate with interdigitated transducers to propagate SAW. Low temperature photoluminescence spectroscopy was used to characterize the system. We observe that the dipolar interlayer excitons couple to SAW and their optical emission is modulated accordingly.