Electrical-optical analysis of photonic crystals GaN-based high power light emitting diodes

Although photonic crystals (PhCs) have been used to enhance the light extraction efficiency (LEE) of light emitting diodes (LEDs) in a lot of researches, the effects of PhCs on the electrical and optical characteristics of GaN-based high power LEDs have been rarely analyzed simultaneously. Herein, the 3D finite-element method (FEM) was employed to investigate the current density distribution in the active layer of LEDs while the LEE was calculated based on the finite-difference time-domain method. Then the influences of several parameters, including the radius, the filling factor, and the etching depth of PhCs on the current density distribution and external quantum efficiency (EQE) of LEDs were examined. It was found that the configurations of PhCs had a significant influence on the electrical and optical performances of LEDs. With the optimized parameters, a 62 % enhancement of EQE and more uniform current density distribution have been obtained comparing to those of LEDs with planar ITO. These analysis results can facilitate the identification of the design rules for high power, high efficiency LEDs.