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Photonic crystal light-emitting diodes fabricated by microsphere lithography
1Department of Electrical and Electronic Engineering, University of Hong Kong, Pokfulam road, Hong Kong.
Nanotechnology
|August 11, 2011
Summary
Microsphere lithography created a photonic crystal on GaN LEDs, enhancing light output. This novel method significantly boosts photoluminescence and electroluminescence for improved LED performance.
Area of Science:
- Materials Science
- Optoelectronics
- Nanotechnology
Background:
- Gallium Nitride (GaN) Light Emitting Diodes (LEDs) are crucial for efficient lighting.
- Enhancing light extraction efficiency in LEDs is a key research area.
- Conventional lithography methods can be complex and costly for LED fabrication.
Purpose of the Study:
- To develop an alternative fabrication method for photonic crystals on GaN LEDs.
- To investigate the impact of photonic crystals on LED light extraction efficiency.
- To analyze the mechanisms behind enhanced light emission.
Main Methods:
- Fabrication of a two-dimensional photonic crystal using microsphere lithography on a GaN LED substrate.
- Utilizing self-assembled microspheres as an etch mask for creating a hexagonal array of triangular air-holes.
- Characterization of photoluminescence and electroluminescence of the fabricated photonic crystal LED (PhC LED) structures.
Main Results:
- A significant enhancement in photoluminescence intensity was observed from the PhC LED.
- A twofold increase in electroluminescence was measured from the PhC LED compared to a standard LED.
- Identified contributions from geometrical factors, photonic crystal dispersion, and diffractive properties to light extraction enhancement.
Conclusions:
- Microsphere lithography offers a viable and effective method for creating photonic crystals on GaN LEDs.
- Photonic crystals significantly improve light extraction efficiency in GaN LEDs.
- The enhanced light extraction is attributed to a combination of structural and optical properties of the photonic crystal.
