Enhanced luminous efficacy in phosphor-converted white vertical light-emitting diodes using low index layer

Area of Science:

• Solid State Physics
• Materials Science
• Optoelectronics

Background:

• Gallium nitride (GaN)-based vertical light emitting diodes (VLEDs) are crucial for solid-state lighting.
• Improving luminous efficacy in VLEDs is essential for energy efficiency and performance.

Purpose of the Study:

• To investigate the impact of a silicon dioxide (SiO(2)) layer on the luminous efficacy of GaN-based VLEDs.
• To analyze the optical behavior of VLEDs with and without a SiO(2) top layer.

Main Methods:

• Fabrication of GaN-based VLED chips with a SiO(2) top layer.
• Three-dimensional finite-difference time-domain (FDTD) simulations to model light penetration.
• Empirical testing of VLEDs at a 350 mA injection current.

Main Results:

• The SiO(2) layer reduced light penetration into the VLED chip by approximately 20%.
• Fabricated VLEDs with a SiO(2) layer showed an 8.1% higher luminous efficacy compared to those without.
• The SiO(2) layer effectively reflects photons, preventing their extinction within the chip.

Conclusions:

• A SiO(2) top layer is an effective strategy for enhancing the luminous efficacy of GaN-based VLEDs.
• This approach improves VLED performance without negatively impacting light extraction efficiency.
• The findings contribute to the development of more efficient solid-state lighting technologies.