High-Power GaN-Based Vertical Light-Emitting Diodes on 4-Inch Silicon Substrate

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Devices

Background:

• Gallium Nitride (GaN)-based light-emitting diodes (LEDs) are crucial for efficient lighting.
• Improving heat dissipation and light extraction efficiency (LEE) are key challenges in LED development.
• Vertical LED (VLED) architectures offer potential advantages over traditional flip-chip LED (FCLED) designs.

Purpose of the Study:

• To demonstrate high-power GaN-based VLEDs on silicon substrates.
• To investigate the impact of substrate material and surface texturing on VLED performance.
• To compare the thermal and electrical performance of VLEDs with FCLEDs.

Main Methods:

• Fabrication of GaN-based VLEDs on silicon using laser lift-off (LLO) and Au-In eutectic bonding.
• Surface texturing of the n-GaN layer using KOH solution.
• Numerical simulations and experimental measurements of forward voltage, light output power (LOP), and emission patterns.

Main Results:

• VLEDs fabricated on 4-inch silicon substrates exhibited enhanced heat dissipation and current spreading.
• KOH texturing of the n-GaN surface improved LEE and achieved a near-Lambertian emission pattern.
• Compared to FCLEDs, VLEDs showed a 0.36 V lower forward voltage and 3.7% higher LOP at 350 mA.
• VLEDs demonstrated no light output saturation up to 1280 mA, unlike FCLEDs.

Conclusions:

• GaN-based VLEDs on silicon substrates offer superior thermal management and light output compared to FCLEDs.
• LLO and substrate transfer techniques are effective for fabricating high-performance VLEDs.
• Surface texturing and optimized electrode design are critical for maximizing VLED efficiency and performance.