Electrically tunable localization for interlayer exciton through engineered nanostructures

Interlayer excitons in transition metal dichalcogenide (TMDC) heterobilayers possess long lifetimes and exhibit linear Stark tuning, offering a powerful platform for exploring strongly correlated excitonic systems. Here, we demonstrate electrically tunable confinement of interlayer excitons through nanoscale spatial control of out-of-plane electric fields. By applying an external bias between a flat upper and a nanopatterned lower electrode with sub-50-nm features, we imprint the electrode topography onto the potential of interlayer exciton states by means of spatially varying vertical electric fields.

Simulations show that patterned nano-holes can generate quantum wells with potential depths up to 25 meV and exciton localization radii approaching 3 nm. The observed trapped state in a 2D hexagonal artificial superlattice (with a lattice constant of 50 nm) shows energy quantization together with saturation behavior under nanowatt illumination power, proving its quantum localization nature and revealing signatures of single trapping of single excitons in each lattice site. Transient reflection contrast imaging further reveals the modification of the exciton diffusion in such an artificial superlattice — a macroscopic transport phenomenon arising from nanoscale potential engineering. These results establish a pathway toward programmable quantum simulators based on solid-state excitonic lattices.