Interlayer Raman modes in twisted bilayer TMDCs

Abstract

Twisted bilayer two-dimensional transition-metal dichalgocenides (TMDCs) exhibit a range of novel phenomena such as the formation of moiré excitons and strongly correlated phases. The coupling between the layers is crucial for the resulting physical properties and depends not just on the twist angle but also on the details of the fabrication process. Here, we present an approach for the analysis of this interlayer coupling via Raman spectroscopy. By exciting the C-exciton resonance of the TMDCs, optical (high-frequency) interlayer Raman modes are activated that are too weak in intensity at excitation energies far below the C exciton. This is due to the wave function of the C exciton, which expands - in contrast to A and B excitons - over both layers and, therefore, couples the layers electronically. We present optical interlayer Raman modes in twisted 2L TMDCs and show that they can be used as a measure of the interlayer coupling between the individual layers.

References in corpus (5)

• Anomalous Lattice Vibrations of Single and Few-Layer MoS2
• Observation of Moiré Excitons in WSe2/WS2 Heterostructure Superlattices
• Raman spectroscopy of the interlayer shear mode in few-layer MoS2 flakes
• Newly observed first-order resonant Raman modes in few-layer MoS${}_2$
• Hybrid moiré excitons and trions in twisted MoTe${}_2$-MoSe${}_2$ heterobilayers