Whispering-gallery mode InGaN microdisks on GaN substrates

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• III-nitride materials offer unique optoelectronic properties.
• Homoepitaxial growth on Gallium Nitride (GaN) substrates enables high-quality material fabrication.
• Microdisk resonators are crucial for efficient light confinement and emission.

Purpose of the Study:

• To demonstrate III-nitride microdisks fabricated on GaN substrates.
• To investigate the optical properties and lasing performance of these microdisks.
• To explore their potential for optoelectronic applications.

Main Methods:

• Fabrication of microdisks using III-nitride materials grown epitaxially on GaN substrates.
• Utilizing microsphere lithography for precise patterning of microdisk sidewalls.
• Characterization using photoluminescence and electroluminescence spectroscopy.
• Analysis of whispering-gallery modes (WGMs) and lasing thresholds.

Main Results:

• Achieved high internal quantum efficiency of approximately 40% due to lattice-matched growth and low dislocation density.
• Demonstrated optically smooth sidewalls in 8 µm-diameter microdisks, facilitating whispering-gallery mode formation.
• Observed optically pumped lasing with a low threshold of ~5.2 mJ/cm² and a quality (Q) factor of ~3000 at 436.8 nm.
• Confirmed electroluminescent operation supporting WGMs, consistent with simulations.

Conclusions:

• Homoepitaxial III-nitride microdisks on GaN substrates exhibit excellent optical properties.
• The fabricated microdisks demonstrate efficient lasing and electroluminescence, supporting WGMs.
• These results highlight the potential of III-nitride microdisks for advanced optoelectronic devices.