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Indirect bandgap MoSe2 resonators for light-emitting nanophotonics
Bogdan R Borodin1, Fedor A Benimetskiy2, Valery Yu Davydov1
1Ioffe Institute, Saint Petersburg, 194021, Russia. brborodin@gmail.com.
Nanoscale Horizons
|February 1, 2023
Summary
Researchers developed a nanofabrication method for microcavities using indirect transition metal dichalcogenides (TMDs). This technique significantly enhances photoluminescence in whispering gallery mode resonators, opening new avenues in nanophotonics.
Area of Science:
- Materials Science
- Optics
- Nanotechnology
Background:
- Transition metal dichalcogenides (TMDs) possess unique optical properties valuable for nanophotonics.
- Bulk TMDs exhibit an indirect bandgap, limiting their use as light emitters, unlike their monolayer counterparts.
- The high refractive index of TMDs is advantageous for light trapping and creating high-quality (high-Q) resonators.
Purpose of the Study:
- To propose a nanofabrication method for creating microcavities from indirect TMD multilayer flakes.
- To achieve significant resonant photoluminescence enhancement in these microcavities via cavity modes.
- To investigate the optical properties and emission mechanisms of fabricated whispering gallery mode (WGM) resonators.
Main Methods:
- Fabrication of WGM resonators from bulk indirect Molybdenum Diselenide (MoSe₂) using resistless scanning probe lithography.
- Micro-photoluminescence (μ-PL) spectroscopy to analyze WGM spectra and enhancement factors.
- Scattering experiments and numerical simulations to validate WGM characteristics.
- Temperature-dependent photoluminescence (PL) measurements to study emission mechanisms.
Main Results:
- Successful fabrication of WGM resonators from indirect MoSe₂ flakes.
- Observed pronounced resonant photoluminescence enhancement up to 100 times due to cavity modes.
- Experimental validation of WGM features through scattering and agreement with simulations.
- Identification of two distinct photoluminescence mechanisms with different temperature dependencies: indirect PL (temperature-sensitive) and direct PL (temperature-independent).
Conclusions:
- The proposed nanofabrication approach enables effective resonant photoluminescence enhancement in indirect TMD microcavities.
- The fabricated resonators demonstrate promising potential for applications in nanophotonics.
- Understanding the dual emission mechanisms provides insights for optimizing light-emitting devices based on TMDs.
