Controlling interlayer excitons in MoS2 layers grown by chemical vapor deposition

Abstract

Combining MoS₂ monolayers to form multilayers allows to access new functionalities. Deterministic assembly of large area van der Waals structures requires concrete indicators of successful interlayer coupling in bilayers grown by chemical vapor deposition. In this work, we examine the correlation between the stacking order and the interlayer coupling of valence states in both as-grown MoS₂ homobilayer samples and in artificially stacked bilayers from monolayers, all grown by chemical vapor deposition. We show that hole delocalization over the bilayer is only allowed in 2H stacking and results in strong interlayer exciton absorption and also in a larger A-B exciton separation as compared to 3R bilayers. Comparing 2H and 3R reflectivity spectra allows to extract an interlayer coupling energy of about t_⊥ = 49 meV. Beyond DFT calculations including excitonic effects confirm signatures of efficient interlayer coupling for 2H stacking in agreement with our experiments.

The authors investigate the interplay between the stacking order and the interlayer coupling in MoS₂ homobilayers as well as artificially stacked bilayers grown by chemical vapour deposition, and identify the interlayer exciton absorption and A-B exciton separation as indicators for interlayer coupling.