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Local Optical Properties in CVD-Grown Monolayer WS2 Flakes
Michele Magnozzi1,2, Theo Pflug3,4, Marzia Ferrera1
1OptMatLab, Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, 16146 Genova, Italy.
The Journal of Physical Chemistry. C, Nanomaterials and Interfaces
|September 6, 2021
Summary
Imaging spectroscopic ellipsometry reveals that exciton-induced light absorption and emission in monolayer tungsten disulfide (WS₂) are not always proportional at the microscopic scale. Microstructural variations influence these processes differently across the material.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Excitons are fundamental to light absorption and emission in monolayer transition-metal dichalcogenides (TMDs).
- Current microscopic studies primarily focus on radiative recombination, neglecting absorption dynamics.
Purpose of the Study:
- To investigate the spatial dependence of the dielectric function in chemical vapor deposition (CVD)-grown WS₂.
- To understand the spatially varying, exciton-induced light absorption in monolayer WS₂.
- To compare absorption and emission characteristics at the microscopic scale.
Main Methods:
- Utilized imaging spectroscopic ellipsometry (ISE) for microscopic lateral resolution.
- Analyzed spatially varying dielectric function and exciton-induced light absorption.
- Correlated ISE data with imaging photoluminescence spectroscopy.
Main Results:
- Observed spatially dependent dielectric function and exciton-induced absorption in monolayer WS₂.
- Found correlated and uncorrelated features between absorption and emission spectra.
- Demonstrated that exciton absorption and emission are not always proportional at the microscale.
Conclusions:
- Microstructural modulations across WS₂ flakes influence light absorption and re-emission differently.
- The study highlights the importance of considering both absorption and emission pathways for a complete understanding of excitonic behavior.
- Provides new insights into the spatially resolved optoelectronic properties of 2D materials.
