InGaN/GaN microdisks enabled by nanoporous GaN cladding.

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Nitride microcavities are crucial for optoelectronic devices.
• Conventional fabrication methods like the undercut technique have limitations in supporting all cavity modes.

Purpose of the Study:

• To introduce nanoporous gallium nitride (NP GaN) as a novel technique for creating out-of-plane index guiding in nitride microcavities.
• To demonstrate the advantages of NP GaN over the undercut technique for supporting diverse cavity modes.

Main Methods:

• Fabrication of GaN microdisk cavities using NP GaN as the bottom low-index layer.
• Continuous-wave optical pumping to characterize cavity performance.
• Rate equation analysis to estimate the spontaneous emission coupling factor (β).

Main Results:

• Achieved a cold cavity with a quality factor (Q) > 2,000.
• Demonstrated lasing with threshold optical pumping powers of ~60 kW/cm² (r=10 μm) and ~7 kW/cm² (r=50 μm).
• Estimated a spontaneous coupling factor (β) of ~1E-3, an order of magnitude higher than previous reports.

Conclusions:

• NP GaN fabrication is a versatile technique for nitride microcavities, supporting all cavity modes.
• NP GaN offers significant advantages over the undercut technique, leading to improved laser efficiency.
• NP GaN is a promising alternative for future nitride microcavity applications.