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Whispering gallery mode lasing from hexagonal shaped layered lead iodide crystals
Xinfeng Liu1, Son Tung Ha, Qing Zhang
1Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371, Singapore.
ACS Nano
|January 7, 2015
Summary
Researchers synthesized lead iodide (PbI2) platelets and observed whispering gallery mode (WGM) lasing. The study highlights thickness-dependent optical gain properties for optoelectronic device optimization.
Area of Science:
- Materials Science
- Optoelectronics
- Solid State Physics
Background:
- Lead iodide (PbI2) is a layered semiconductor with potential for optoelectronic applications.
- Understanding optical gain properties is crucial for developing light-emitting devices.
Purpose of the Study:
- To synthesize regularly shaped PbI2 platelets and investigate their optical gain properties.
- To demonstrate and characterize whispering gallery mode (WGM) lasing in PbI2 platelets.
- To explore the influence of platelet thickness on lasing characteristics and device optimization.
Main Methods:
- Chemical vapor deposition (CVD) for synthesizing PbI2 platelets.
- Photoluminescence (PL) spectroscopy (power-dependent and time-resolved) to study optical properties.
- Finite-difference time-domain (FDTD) simulations to confirm lasing mechanisms.
Main Results:
- Successfully synthesized single crystalline PbI2 platelets with thicknesses from 10-500 nm.
- Observed near band edge emission around 500 nm.
- Demonstrated WGM lasing in hexagonal PbI2 platelets between 77-210 K, even in platelets as thin as 45 nm.
- Confirmed planar WGM lasing mechanism through simulations and edge-length dependent threshold analysis.
- Identified biexcitonic nature of WGM lasing.
- Found the lowest lasing threshold in platelets approximately 120 nm thick due to optimal Fabry-Pérot resonance.
Conclusions:
- PbI2 platelets exhibit WGM lasing, indicating their potential for planar light sources.
- The thickness-dependent threshold is a critical factor for optimizing optoelectronic devices based on layered semiconductors.
- This research paves the way for advanced optoelectronic devices utilizing layered semiconductor materials.
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