High-efficiency vertical GaN slab light-emitting diodes using self-coherent directional emitters

Area of Science:

• Optoelectronics
• Materials Science
• Semiconductor Devices

Background:

• Gallium Nitride (GaN) based light-emitting diodes (LEDs) are crucial for solid-state lighting.
• Improving light extraction efficiency in LEDs is a key challenge for enhanced performance.

Purpose of the Study:

• To demonstrate a highly-efficient, large-area GaN slab LED utilizing a vertically directional emitter.
• To enhance light extraction efficiency through constructive interference and optimized device architecture.

Main Methods:

• Fabrication of a 1x1 mm² GaN slab LED.
• Utilizing constructive interference to create a vertically directional emitter.
• Optimizing dielectric layer thickness between the emitter and a bottom silver mirror.
• Incorporating a randomly textured surface as a light extractor.

Main Results:

• Achieved a vertically directional emission profile by tuning dielectric layer thickness.
• Demonstrated effective coupling of vertical radiation into leaky modes.
• Observed a 1.4-fold increase in output power compared to non-patterned devices at 350 mA.
• Confirmed no electrical degradation in the patterned device.

Conclusions:

• The developed GaN slab LED design significantly enhances light extraction efficiency.
• Vertical emission achieved through constructive interference is effective for high-efficiency LEDs.
• Surface texturing further boosts output power without compromising device reliability.