Size-dependent photon scattering effects in AlGaN-based deep ultraviolet LEDs with varied length-to-width ratios

Area of Science:

• Optoelectronics
• Semiconductor Devices

Background:

• Deep ultraviolet (DUV) Light Emitting Diodes (LEDs) are crucial for various applications.
• Optimizing optical performance, particularly Light Extraction Efficiency (LEE), is key for DUV LED development.

Purpose of the Study:

• To systematically investigate the effect of the mesa Length/Width (L/W) ratio on the optical performance of DUV LEDs.
• To understand the underlying mechanisms causing size-dependent optical behavior in DUV LEDs with varying mesa L/W ratios.

Main Methods:

• Numerical simulations or experimental measurements of DUV LEDs with varying mesa L/W ratios.
• Analysis of light propagation, scattering, and escape pathways within the DUV LED structure.

Main Results:

• For large-sized DUV LEDs, increasing the L/W ratio enhances LEE by improving light reflection into the escape cone and increasing side-light extraction.
• For small-sized DUV LEDs, increasing the L/W ratio decreases LEE due to increased absorption by GaN and top metal from internally reflected light.
• Different scattering mechanisms are identified for large and small chips at varying L/W ratios.

Conclusions:

• The mesa L/W ratio has a size-dependent effect on DUV LED LEE.
• Findings provide essential geometry design principles for optimizing DUV LEDs of different sizes.
• Understanding scattering mechanisms is crucial for tailoring DUV LED optical performance.