High performance GaN-based flip-chip LEDs with different electrode patterns.

Area of Science:

• Optoelectronics
• Solid-state lighting
• Semiconductor devices

Background:

• Flip-chip light-emitting diodes (FCLEDs) offer enhanced thermal and electrical performance.
• Optimizing electrode design is crucial for efficient current spreading and light extraction in FCLEDs.
• Blue Indium Gallium Nitride/Gallium Nitride (InGaN/GaN) LEDs are vital for various lighting applications.

Purpose of the Study:

• To fabricate and characterize high-performance FCLEDs with a novel Ni/Ag metallic film p-type electrode.
• To investigate the impact of geometric electrode patterns on current spreading and optoelectronic performance.
• To propose design strategies for enhancing FCLED efficiency and thermal management.

Main Methods:

• Fabrication of FCLEDs utilizing a Ni/Ag metallic film as a high-reflectivity p-type electrode (92.67% reflectivity).
• Experimental investigation and simulation of devices with varying geometric electrode patterns to analyze current spreading.
• Characterization of current-voltage (I-V) properties, light output power, and thermal performance using optoelectronic measurements and infrared imaging.

Main Results:

• FCLEDs exhibited forward voltages of approximately 3.6 V at 350 mA.
• A circle-round electrode pattern achieved a light output power of 368 mW at 700 mA injection current.
• Analysis revealed correlations between electrode design, current spreading, light output, and thermal characteristics.

Conclusions:

• The Ni/Ag metallic film serves as an effective high-reflectivity mirror for FCLED p-type electrodes.
• Geometric electrode design significantly influences current spreading, leading to improved FCLED performance.
• The study provides valuable design methodologies for optimizing FCLEDs for higher efficiency and better thermal management.