All-BN distributed Bragg reflectors fabricated in a single MOCVD process

Area of Science:

• Photonics
• Materials Science
• Nanotechnology

Background:

• Distributed Bragg Reflectors (DBR) are crucial photonic components.
• Existing DBR fabrication often involves complex material combinations or post-processing etching, limiting integration.
• There is a need for simpler, integrable DBR structures.

Purpose of the Study:

• To demonstrate a novel fabrication method for DBR structures using only undoped boron nitride (BN) layers.
• To achieve high refractive index contrast in BN layers through controlled porosity.
• To enable single-step fabrication of DBRs without post-process etching.

Main Methods:

• Utilized metal-organic chemical vapor deposition (MOCVD) for fabricating BN layers.
• Controlled layer porosity by adjusting growth temperatures during MOCVD.
• Fabricated DBR structures with 15.5 pairs of BN layers.

Main Results:

• Achieved DBR structures solely from undoped BN layers with high refractive index contrast.
• Demonstrated a maximum reflectance of 87 ± 1% without etching.
• Showcased tunable maximum reflectance wavelengths from 500 nm to the infrared (IR) region.
• Successfully created an optical microcavity using the fabricated BN DBRs.

Conclusions:

• Developed a single-process fabrication technique for BN DBRs.
• These BN DBRs offer high performance and tunability, suitable for advanced photonic applications.
• The all-BN DBRs are promising for integration with single-photon emitters in hexagonal boron nitride (h-BN) for cavity-based quantum sources.