Abstract

Many studies have introduced electrode patterns to improve current crowding and enhance the light output power of LEDs. This study conducted experimental and numerical analysis to investigate the influence of electrode design on the luminous efficiency of LEDs. An extended p-electrode was used to relieve current crowding commonly encountered at the edge of conventional electrodes. Unfortunately, an extension of the p-electrode obscures light emitted from the active layer. Therefore, we fabricated arrays of holes, 3 or 5 μm in diameter, on the electrodes and compared their effectiveness in enhancing light output efficiency. Optical measurements demonstrated that increasing the diameter of the holes led to an increase in light output power. The maximum output power of the proposed LED was 48.1 mW for an array of 5 μm holes, which is higher than that of 43.8 mW for the conventional LED. At a current injection of 500 mA, the output power of the proposed LED (5 μm holes) was 47.7 mW, which is nearly double that of conventional LED (23.7 mW). Numerical analysis was also used to simulate the distribution of current density in the active layer of the LEDs. The relationship between current spreading length and internal quantum efficiency were used to calculate the distribution of luminous intensity. Further modeling was performed to simulate light output power via Monte Carlo ray tracing. The results of numerical simulation are in strong agreement with those obtained from experiments.

© 2014 IEEE

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