Greatly Enhanced Resonant Exciton-Trion Conversion in Electrically Modulated Atomically Thin WS₂ at Room Temperature.

Area of Science:

• 2D Nanophotonics
• Materials Science
• Quantum Optics

Background:

• Atomically thin semiconductors, like transition metal dichalcogenides (TMDCs), are crucial for 2D nanophotonics.
• Understanding exciton-trion conversion is key to optical tunability in these materials.
• Current limitations include inefficient light-matter interactions, hindering trionic phenomena observation.

Purpose of the Study:

• To demonstrate enhanced exciton-trion conversion in TMDCs using optical cavities.
• To investigate electrical modulation of reflectivity and phase tuning.
• To explore efficient exciton-trion conversion for advanced optical devices.

Main Methods:

• Integration of atomically thin TMDCs within an optical cavity.
• Room-temperature (RT) experiments to measure optical properties.
• Electrical modulation techniques to control reflectivity and phase.

Main Results:

• Greatly enhanced exciton-trion conversion demonstrated at RT.
• Achieved ≈40% reflectivity modulation at exciton and 7% at trion states.
• Observed ≈100% photoluminescence conversion from excitons to trions.
• Demonstrated broadband large phase tuning in monolayer tungsten disulfide.

Conclusions:

• Excitons and trions significantly contribute to electrical modulation of TMDC optical parameters at RT.
• The study highlights a clear physical mechanism for efficient exciton-trion conversion.
• Realization of electrical tunable, multi-functional ultra-thin optical devices using 2D materials is feasible.