Enhancing extraction efficiency from GaN-based LED by using an omni-directional reflector and photonic crystal

To enhance the light extraction efficiency of traditional light-emitting diodes（LEDs） by reducing the total internal reflection,an omni-directional reflector（ODR） and photonic crystal are adopted in the paper.The structures of photonic crystal and the ODR are designed by diffraction theory and finite difference time domain（FDTD） method.The photonic crystal is employed in the p-GaN layer and the ODR composed of TiO2/SiO2 is designed between the active region and substrate.The simulation results indicate that the light extraction of LEDs can be enhanced by 11.6 times,and the external quantum efficiency of LEDs will be effectively improved.