Electrically Tunable Quantum Control for Interlayer Exciton Superlattices with Nanoelectrodes

Interlayer exciton state in transition metal dichalcogenide heterobilayers with the type-II band alignment feature electrically tunable energy levels by a linear Stark effect and display much longer lifetimes since their recombination rate is limited by quantum tunneling. By leveraging the state-of-the-art nanofabrication technology, we explore that, instead of relying on the passive built-in potential in moiré heterobilayers, we can create extrinsic but dynamically tunable electrostatic potential distributions for interlayer excitons with nanometer resolution. This is achieved by imprinting the topography of the nanoelectrode into the potential of the interlayer exciton state via the non-uniform vertical electric-field distribution across the heterobilayer plane generated by applying an external bias between the top (flat) and bottom nanopatterned electrode. Our simulations show that the patterned electrode with nano-holes (diameter ~ 25 nm) can trap interlayer excitons in quantum wells with the radius of the center of mass wave function down to 3 nm, leading to possibly strong on-site interaction. Cryogenic photoluminescence measurements confirm the validity of this concept by observing the trapped interlayer exciton state spectroscopically with the potential depth electrically tuned continuously from 0 to ~ 25 meV. Related power-, position-, and temperature-dependent measurements have been conducted to reveal the properties and interactions of the confined interlayer excitons.