Porous AlGaN-Based Ultraviolet Distributed Bragg Reflectors.

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Gallium nitride (GaN)-based distributed Bragg reflectors (DBRs) for visible light have been fabricated using electrochemical etching (ECE).
• Ultraviolet light-emitting diodes (UV LEDs) suffer from low efficiency, partly due to limitations in UV reflector technology.
• Non-absorbing UV reflectors are crucial for enhancing UV LED performance.

Purpose of the Study:

• To apply the established ECE process to fabricate AlGaN-based ultraviolet distributed Bragg reflectors (UV DBRs).
• To investigate the potential of ECE for creating efficient UV reflectors to improve UV LED performance.

Main Methods:

• Utilized dislocation-related vertical etching channels in gallium nitride (GaN).
• Applied a simple electrochemical etching (ECE) process to AlGaN material.
• Fabricated layered porous AlGaN structures for UV DBR applications.

Main Results:

• Demonstrated porous AlGaN-based UV DBRs with a peak reflectance of 89% at 324 nm.
• Observed low device uniformity attributed to V-pits in the as-grown AlGaN material.
• Identified that V-pits in the material alter the electrochemical etching process.

Conclusions:

• The ECE process is a viable method for fabricating AlGaN-based UV reflectors.
• Optimization of AlGaN material growth, specifically reducing V-pit density, is necessary for improved device uniformity.
• The ECE technique holds promise for the future fabrication of efficient UV reflectors for UV LEDs.