GaN microring waveguide resonators bonded to silicon substrate by a two-step polymer process.

Area of Science:

• Materials Science
• Photonics
• Semiconductor Device Fabrication

Background:

• Hybrid integration of dissimilar materials like Gallium Nitride (GaN) and Silicon (Si) is crucial for advanced photonic devices.
• Existing fabrication methods face challenges in achieving efficient integration and maintaining material properties.

Purpose of the Study:

• To fabricate GaN microring waveguide resonators on a Si substrate for future hybrid integration.
• To investigate the optical performance of these GaN microring resonators.

Main Methods:

• Growth of a 1000 nm GaN layer on a Si(111) substrate using metal-organic chemical vapor deposition (MOCVD) with a buffer layer.
• Polymer bonding of the GaN/Si wafer to a Si(100) wafer using a two-step process to avoid air bubbles.
• Backside thinning via fast atom beam etching to create rib waveguides and remove the buffer layer.

Main Results:

• Fabricated GaN microring resonators with specific dimensions (510 nm core thickness, 1000 nm width).
• Measured waveguide losses of 4.0±1.7 dB/mm at 1.55 μm wavelength.
• Achieved quality factors ranging from 1710 to 2820 for microrings with radii from 30 to 60 μm.

Conclusions:

• Successful fabrication of GaN microring waveguide resonators on Si substrates via polymer bonding.
• Demonstrated potential for hybrid integration of GaN and Si photonics.
• The fabricated devices exhibit promising optical characteristics for photonic applications.