Is a thin p-GaN layer possible for making high-efficiency AlGaN-based deep-ultraviolet light-emitting diodes?

Area of Science:

• Optoelectronics
• Semiconductor Devices
• Materials Science

Background:

• AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs) are crucial for various applications.
• The efficiency of DUV LEDs is significantly influenced by the p-GaN layer thickness and current spreading.
• Optimizing device architecture is key to overcoming efficiency limitations.

Purpose of the Study:

• To investigate the impact of p-GaN layer thickness on the efficiency of AlGaN-based DUV LEDs.
• To explore methods for mitigating efficiency losses caused by thin p-GaN layers.
• To demonstrate the effectiveness of a current spreading layer in enhancing DUV LED performance.

Main Methods:

• Experimental fabrication and characterization of DUV LEDs with varying p-GaN layer thicknesses.
• Numerical simulations to analyze current distribution and optical performance.
• Implementation and testing of a p-AlGaN/n-AlGaN/p-AlGaN (PNP-AlGaN) structured current spreading layer.

Main Results:

• Decreasing p-GaN layer thickness increases light extraction efficiency (LEE) due to reduced absorption.
• External quantum efficiency (EQE) trends correlate with LEE improvements.
• A thin p-GaN layer can lead to current crowding, reducing internal quantum efficiency (IQE).
• The PNP-AlGaN current spreading layer effectively suppresses current crowding.
• Suppression of current crowding significantly enhances EQE and optical power in DUV LEDs with thin p-GaN layers.

Conclusions:

• Thin p-GaN layers are beneficial for enhancing LEE in DUV LEDs.
• Current spreading layers are essential for realizing the full potential of thin p-GaN layers.
• Optimized DUV LED design incorporating thin p-GaN and current spreading layers leads to significant efficiency and optical power improvements.