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Moiré Intralayer Excitons in a MoSe2/MoS2 Heterostructure
Nan Zhang1, Alessandro Surrente1, Michał Baranowski1,2
1Laboratoire National des Champs Magnétiques Intenses , UPR 3228, CNRS-UGA-UPS-INSA, 38042/31400 Grenoble/Toulouse , France.
Nano Letters
|November 8, 2018
Summary
Moiré patterns in transition metal dichalcogenide heterobilayers significantly alter exciton properties. This study observed moiré-induced splitting in MoSe2 exciton and trion spectra, aligning with theoretical models.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Optoelectronics
Background:
- Van der Waals (vdW) heterostructures, particularly transition metal dichalcogenides (TMDs), exhibit unique electronic and optical properties.
- Moiré patterns, arising from lattice mismatch or twist angles in vdW bilayers, create periodic potential variations.
- These periodic potentials are predicted to strongly influence exciton behavior in TMDs.
Purpose of the Study:
- To investigate the impact of moiré superlattices on the optical properties of excitons and trions in MoSe2/MoS2 heterobilayers.
- To experimentally verify theoretical predictions regarding moiré-induced modifications of exciton spectra.
Main Methods:
- Fabrication of a MoSe2/MoS2 heterobilayer encapsulated in hexagonal boron nitride (hBN).
- Characterization of the moiré pattern formation and its influence on optical spectra.
- Spectroscopic analysis (emission and absorption) to observe exciton and trion behavior.
Main Results:
- The formation of a moiré pattern in the MoSe2/MoS2 heterobilayer was confirmed.
- A distinct splitting of the MoSe2 exciton and trion emission peaks was observed.
- The exciton absorption spectrum also showed evidence of splitting.
- The measured energy splitting between the spectral peaks was found to be in excellent agreement with theoretical predictions.
Conclusions:
- The periodic potential of the moiré superlattice significantly modifies the electronic band structure of the MoSe2 layer.
- Moiré-induced potential variations lead to the splitting of exciton and trion energy levels, impacting their optical spectra.
- Experimental results validate theoretical models predicting the influence of moiré patterns on TMD heterostructures.
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