Surface Microstructure Enhanced Cryogenic Infrared Light Emitting Diodes for Semiconductor Broadband Upconversion.

Area of Science:

• Optoelectronics
• Materials Science
• Solid State Physics

Background:

• Broadband upconversion is crucial for solar cells, imaging, and biomedicine.
• Low efficiency of light-emitting diodes (LEDs) hinders broadband upconversion performance.
• Surface microstructures offer a potential solution to enhance LED efficiency.

Purpose of the Study:

• To investigate the use of surface microstructures to enhance the electroluminescence efficiency (ELE) of LEDs.
• To systematically study the cryogenic-temperature performance of microstructure-coupled LEDs.
• To elucidate the enhancement mechanism and light-emitting characteristics of these optimized LEDs.

Main Methods:

• Experimental and theoretical investigations of microstructure-coupled LEDs at cryogenic temperatures.
• Analysis of electroluminescence efficiency, luminescence spectrum, and recombination rate.
• Comparison of surface luminescence uniformity between optimized and unoptimized devices.

Main Results:

• Nearly 35% enhancement in ELE for optimized structures at cryogenic temperatures and weak injection currents.
• Attribution of ELE enhancement to efficient carrier injection and high recombination rates in the active region.
• Demonstration of improved surface luminescence uniformity in the optimized LED.

Conclusions:

• Surface microstructures significantly enhance LED electroluminescence efficiency at cryogenic temperatures.
• The optimized microstructure-coupled LED provides a promising approach for broadband upconversion applications.
• This work offers guidance for optimizing upconverters in cryogenic environments.