Modeling of internal quantum efficiency in micro-LEDs with surface nonradiative recombination.

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Indium Gallium Nitride (InGaN) based micro-light-emitting diodes (micro-LEDs) are crucial for advanced display technologies.
• A significant challenge in micro-LED development is the efficiency droop observed in smaller devices, particularly blue InGaN micro-LEDs.

Purpose of the Study:

• To investigate the size-dependent efficiency characteristics of blue and red InGaN micro-LEDs.
• To develop a comprehensive internal quantum efficiency (IQE) model that accounts for surface recombination velocity (SRV) and diffusion length.

Main Methods:

• Development of a theoretical model for IQE in micro-LEDs.
• Inclusion of surface recombination velocity (SRV) and diffusion length as key parameters in the model.
• Analysis of efficiency variations with chip size for different diffusion lengths.

Main Results:

• For micro-LEDs with diffusion lengths > 1 µm, IQE significantly decreases with smaller chip sizes or increased SRV.
• For micro-LEDs with diffusion lengths < 0.1 µm (characteristic of red InGaN LEDs), IQE remains relatively stable across varying chip sizes and SRV.
• The model accurately predicts the observed efficiency trends in both blue and red micro-LEDs.

Conclusions:

• The developed IQE model provides critical insights into the efficiency limitations of InGaN micro-LEDs.
• Understanding the interplay between diffusion length and SRV is essential for optimizing micro-LED performance across different colors.
• This research contributes to the advancement of high-efficiency micro-LED technology.