Vertical InGaN light-emitting diodes with a sapphire-face-up structure

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• Gallium nitride (GaN)-based light-emitting diodes (LEDs) are crucial for efficient lighting.
• Conventional lateral GaN LEDs on sapphire substrates face limitations in light extraction and thermal management.
• Developing vertical GaN LEDs is essential for enhanced performance and broader applications.

Purpose of the Study:

• To fabricate vertical GaN-based LEDs on silicon substrates.
• To investigate the performance advantages of vertical GaN/Si LEDs over conventional lateral GaN/sapphire LEDs.
• To explore the impact of wafer-bonding and substrate thinning techniques on LED characteristics.

Main Methods:

• Fabrication of vertical GaN-based LEDs using wafer-bonding on a Si substrate.
• Utilizing lapping and dry-etching for sapphire substrate thinning, enabling a sapphire-face-up structure.
• Characterization of fabricated vertical LEDs, including light output power and forward voltage measurements at various current densities.

Main Results:

• Vertical GaN/Si LEDs exhibit significantly higher light output power compared to conventional lateral GaN/sapphire LEDs.
• Reduced power degradation at high driving currents was observed in vertical GaN/Si LEDs.
• At 350 mA injection current, a 60% enhancement in output power and a 5% reduction in forward voltage were achieved.

Conclusions:

• Vertical GaN/Si LEDs offer superior performance, including enhanced light output and improved thermal management, due to their vertical conduction structure.
• The wafer-bonding and substrate thinning methods are effective for creating high-performance vertical LEDs.
• These findings pave the way for more efficient and reliable GaN-based lighting technologies.