Probing moire excitons in MoSe2/WSe2 heterobilayers by combined micro-photoluminescence and lateral force microscopy

TL;DR

This study combines micro-photoluminescence and lateral force microscopy to explore interlayer excitons in MoSe2/WSe2 heterobilayers, revealing how moiré superlattices influence exciton localization and energy distribution.

Contribution

It introduces a combined microscopy approach to directly correlate moiré lattice structure with exciton optical properties in heterobilayers.

Findings

Moiré superlattice is continuous near the optical diffraction limit.

Photoluminescence shows narrow lines consistent with moiré geometry.

Interlayer excitons are confined by the moiré potential.

Abstract

We study interlayer excitons in MoSe2/WSe2 heterobilayers, by combining lateral force microscopy and micro-photoluminescence spectroscopy. This allows us to correlate the spatial profile of the moir\'e superlattice with the distribution of optically active states accessible to interlayer excitons. In heterostructures where a few degrees twist angle is imposed between the MoSe and WSe crystallographic axes, we show that a continuous moir\'e lattice is realized across areas close to the optical diffraction limit. In such regions, the photoluminescence reduces to a few narrow-band lines only, energetically distributed consistently with the geometry of the moir\'e lattice. This correlation reveals that interlayer excitons explore a controlled periodic confinement, paving the way towards implementations of Bose-Hubbard models.