Abstract
Light extraction of InGaN/GaN based surface-patterned vertical blue light emitting diodes (LEDs) is investigated by the use of ray-tracing approach. To optimize the light extraction efficiency of LEDs, various types of facet-patterning have been introduced on the free surfaces of the n-GaN epitaxial layer. A drastic increase in light extraction efficiency of the LED is observed due to increase of random and multiple scattering of light through patterned surfaces. The improvement in overall light extraction efficiency for the LEDs having rectangular and hexagonal patterning in free surfaces have been estimated around 2.25 and 3.39 times of that of the LED structure with smooth free surface (i.e., without any patterning), respectively.