Enhanced light extraction from AlGaInP-based red light-emitting diodes with photonic crystals
Optics Express
|March 17, 2021
Summary
Photonic crystals (PCs) enhance light-emitting diodes (LEDs). Surface and embedded PC designs improved LED brightness and light control, showing promise for mini and micro LEDs.
Area of Science:
- Optoelectronics
- Materials Science
- Solid-state lighting
Background:
- Photonic crystals (PCs) are known for enhancing light extraction efficiency in light-emitting diodes (LEDs).
- AlGaInP-based vertical LEDs (VLEDs) are a key technology for high-brightness applications.
- Controlling light emission is crucial for improving LED performance.
Purpose of the Study:
- To fabricate and evaluate high-brightness AlGaInP-based VLEDs incorporating surface photonic crystals (SPCLEDs) and embedded photonic crystals (EPCLEDs).
- To compare the optical and electrical performance of SPCLEDs and EPCLEDs against normal LEDs (NLEDs).
- To assess the potential of PC-enhanced LEDs for advanced display technologies like mini and micro LEDs.
Main Methods:
- Fabrication of AlGaInP-based VLEDs with integrated surface and embedded photonic crystal structures.
- Photoluminescence (PL) intensity measurements to quantify light emission enhancement.
- Electroluminescence (EL) measurements, including threshold voltage and light output power (LOP) analysis.
- Analysis of reflection patterns to verify light control by photonic crystals.
- Evaluation of luminous uniformity and thermal performance.
Main Results:
- SPCLEDs and EPCLEDs exhibited significant improvements in photoluminescence intensity, up to 30% and 60% respectively, compared to NLEDs.
- Reflection patterns confirmed the light-controlling capabilities of the photonic crystals.
- Electroluminescent measurements showed similar threshold voltages for all LED types.
- Light output power (LOP) increased by up to 24% for SPCLEDs and 11% for EPCLEDs at 200 mA.
- EPCLEDs showed earlier LOP decay due to increased heat production, while both PC-enhanced LEDs demonstrated better luminous uniformity.
Conclusions:
- Surface and embedded photonic crystals effectively enhance the performance of AlGaInP-based VLEDs.
- SPCLEDs offer improved light output power and uniformity with comparable threshold voltages to NLEDs.
- While EPCLEDs show performance gains, thermal management is a consideration for their widespread application.
- PC-enhanced LEDs hold significant potential for advancing high-brightness applications, particularly in mini and micro LED technologies.
