Improvement of the Light Extraction Efficiency of InGaN/GaN Blue Light Emitting Diodes Using ZnO Nanostructures

Herein, we report the effects of geometric morphology of ZnO nanostructures on the extraction efficiency of GaN-based light emitting diodes (LEDs). We performed numerical analysis based on the two-dimensional (2D) finite difference of time domain (FDTD) method that was utilized to calculate the light extraction efficiency of the LEDs. We found that the extraction efficiency of the LED increased upon changing the shape of ZnO nanostructure from nanorods to pencil-likenanorods. The current-voltage characteristics of the LED with ZnO nanorods or pencil-like nanorods were similar to those of the LED that did not contain any ZnO nanostructures. The light output power of the LEDs containing ZnO nanorods or pencil-like nanorods at 100 mA increased additionally to 28% and 39%, respectively, relative to that of the LED that did not contain any ZnO nanostructures. These results confirm that the geometric morphology of the ZnO nanostructure plays an important role in improving the extraction efficiency of the LEDs.