Creating Superlattices for Interlayer Excitons with Metasurface Nanoelectrodes

Atomically-thin transition metal dichalcogenide (TMDC) monolayers have attracted significant and broad interest in the last decade. They serve as a promising material platform for future low-dimensional electronics and optoelectronics because of their exceptional charge-carrier mobility and quantum yield, and provide a clean 2D system for fundamental physics study because of the enhanced quantum effects and correlations due to the reduction of the available states in the system. As compared with intralayer excitons in monolayers, interlayer excitons in TMDC heterostructures display longer lifetimes as their recombination rate is limited by the tunneling effect, resulting in a diffusion length of up to a few micrometers and creating an exciting playground for quantum many-body physics study.<br/><br/>Here, we propose that with state-of-the-art nanofabrication techniques, we can spatially control the energy level of interlayer excitons down to the nanometer scale via the DC Stack effect with the carefully designed metasurface nanoelectrodes. For instance, an electrode with patterned nano-holes (diameter ~ 30 nm) can trap interlayer excitons in quantum wells. The depth of the quantum wells can be scaled with the applied external vertical electric field up to ~ 100 meV. A superlattice can therefore be achieved with a periodically nanopatterned hole array (period ~ 50 nm), where its Hamiltonian can be described using a Bose-Hubbard model. By gradually tuning the depth of the quantum wells, a material phase transition (from insulating to conducting) is expected. What’s more, a more complicated material phase (i.e., Hamiltonian), including but not limited to defect states, quasi-crystal, as well as general quantum metasurfaces, can all be simulated by engineering the geometry of the metasurface electrodes and associated DC electric field distribution.