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Residue-Free Fabrication of van der Waals Heterostructures of Two-Dimensional Materials
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Interlayer Excitons with Large Optical Amplitudes in Layered van der Waals Materials
Thorsten Deilmann1, Kristian Sommer Thygesen1,2
1CAMD, Department of Physics , Technical University of Denmark , DK-2800 Kongens Lyngby , Denmark.
Nano Letters
|April 19, 2018
Summary
Vertically stacked 2D materials enable nanoscale light control. Applying electric fields to bilayer MoS2 tunes interlayer excitons, offering tunable optical properties for advanced materials.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Vertically stacked 2D materials offer unique platforms for light-matter interactions.
- These materials exhibit distinct intra- and interlayer electronic excitations.
- Bilayer MoS2 is a representative van der Waals material for studying excitonic properties.
Purpose of the Study:
- To investigate the prominent excitons in bilayer MoS2.
- To explore the evolution of excitonic states under an applied electric field.
- To understand how band alignment affects excitons in 2D heterostructures.
Main Methods:
- First-principles many-body calculations were employed.
- An electric field was applied perpendicular to the bilayer MoS2.
- Excitonic states were analyzed across varying band alignments (line-up to Type II).
Main Results:
- The lowest exciton in bilayer MoS2 exhibits intralayer character and is field-independent at moderate strengths.
- Higher-lying excitons possess interlayer character, mixing intralayer B and dark charge transfer excitons.
- These mixed interlayer excitons show strong optical amplitude and are tunable by electric fields.
Conclusions:
- First-principles findings are reproducible with a simplified excitonic model Hamiltonian.
- The model can be extended to analyze more complex van der Waals materials.
- Electric field control of interlayer excitons in 2D materials is demonstrated.
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