High-Quality Hexagonal Nonlayered CdS Nanoplatelets for Low-Threshold Whispering-Gallery-Mode Lasing

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Conventional semiconductor nanolasers face high thresholds due to quantum efficiency and crystal quality limitations.
• Applications in high-density storage and optical communication require efficient, low-threshold micro/nanolasers.

Purpose of the Study:

• To demonstrate a low-threshold planar laser utilizing high-quality single-crystalline hexagonal cadmium sulfide nanoplatelets (NPLs).
• To investigate the lasing characteristics and threshold dependencies of these novel CdS NPLs.

Main Methods:

• Fabrication of hexagonal CdS NPLs using a self-limited epitaxial growth method.
• Characterization of whispering-gallery-mode lasing at room temperature and 77 K.
• Analysis of edge length and thickness effects on the lasing threshold.

Main Results:

• Achieved room-temperature lasing with a threshold of ≈0.6 µJ cm⁻², the lowest reported for CdS-based lasers.
• Identified exciton-exciton scattering as the origin of lasing action at 77 K.
• Determined threshold inversely proportional to lateral edge length squared, with optimal thickness around 110 nm for vertical confinement.

Conclusions:

• The study presents a new approach for fabricating low-threshold coherent light sources using non-layered materials.
• CdS NPLs demonstrate significant potential for developing advanced optoelectronic devices and integrated photonics.