Heterostructures

The two-dimensional (2D) nature and large excitonic binding energy of transition metal dichalcogenides (TMDs) allow for the exploration of novel quantum optical effects. Using type-II heterostructures formed by stacking MoSe₂ and WSe₂ monolayers, optical excitation generates interlayer excitons, bound electrons and holes residing in spatially separated layers. The out-of-plane, permanent dipole moment of interlayer excitons allows for the control of the emission energy by tuning the vertical electric field using dual-gated devices. By spatially varying the vertical electric field with patterned gates, we can generate potential profiles that can spatially control the interlayer exciton energy. We observe changes in the exciton cloud shape and emission brightness depending on a flat, trapping, or anti-trapping electric field profile. Finally, we estimate an upper-bound interlayer exciton density that can be tuned with the trap depth. With the ability to generate high densities of interlayer excitons, trapped interlayer excitons can serve as a platform for generating and exploring Bose-Einstein condensates at high temperatures.