InGaN light emitting diodes with a laser-treated tapered GaN structure

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Indium Gallium Nitride (InGaN) light-emitting diodes (LEDs) are crucial for solid-state lighting.
• Enhancing LED efficiency and light output power remains a key research objective.
• Interface engineering at the GaN/sapphire substrate is critical for device performance.

Purpose of the Study:

• To improve the light output power and quantum efficiency of InGaN LEDs.
• To investigate the effects of novel interface structures on LED optical properties.
• To explore the relationship between structural modifications and strain release.

Main Methods:

• Fabrication of InGaN LED structures with integrated air-void and tapered GaN features.
• Utilizing laser decomposition and lateral wet etching processes for interface modification.
• Characterization using micro-photoluminescence (PL) and electroluminescence (EL) spectroscopy.
• Analysis of light output power and relative internal quantum efficiency.

Main Results:

• Achieved a 70% enhancement in light output power at 20 mA compared to conventional LEDs.
• Observed periodic variations in micro-photoluminescence intensity and peak wavelengths correlated with engineered structures.
• Reported a slight blueshift in EL and PL spectra due to partial strain release at the GaN/sapphire interface.
• Increased relative internal quantum efficiency from 67.8% to 70.3% attributed to reduced piezoelectric fields.

Conclusions:

• The developed air-void and tapered GaN interface structures effectively enhance InGaN LED performance.
• Interface engineering offers a viable pathway to boost light output power and efficiency.
• Strain modulation at the GaN/sapphire interface plays a significant role in optical characteristics.