Creating lateral quantum wells in monolayer semiconductors by an electrostatic confinement mechanism

Excitons in monolayer TMDC semiconductors have proven to be an excellent platform for revealing much new physics of correlated electronic states and also offer promise for next-generation optoelectronic devices. Lateral confinement, combined with the natural vertical confinement of 2D materials, provides new routes to modify and control excitons, including the possibility of creating arbitrarily placed quantum emitters. Various approaches, such as localized strain and moiré potentials, have been successfully developed. Recent studies have also revealed that excitons in monolayer MoSe2 can be confined effectively at the edge of the top gate in a dual-gated device structure. [1] This confinement results from the spatially localized parallel component of the electric field, as well as from the influence of doping. As a purely electrostatic mechanism, the confinement can easily be switched on or off, as well as tuned continuously.

Here we employ this confinement mechanism to study the interaction between excitons confined by the edges of two parallel, closely spaced electrostatic gates. We demonstrate the independent tunability of two sets of 1D confined states using optical absorption and emission spectroscopy. We further show that a single quantum well for excitons can be formed a result of the two edges for an appropriate geometry. These results advance our capabilities for the manipulation and hybridization of confined excitons, as well as for the creation of large, degenerate quantum emitter arrays.

[1] Thureja, D., Imamoglu, A., Smolenski, T. et al. Electrically tunable quantum confinement of neutral excitons. Nature 606, 298–304 (2022).