High light-extraction efficiency in GaInN light-emitting diode with pyramid reflector

A GaInN light-emitting diode (LED) that employs a new type of reflector consisting of an array of SiO2 pyramids and a reflective Ag layer is demonstrated to have enhanced light extraction compared to GaInN LEDs with a planar Ag reflector. Ray tracing simulations reveal that the pyramid reflector provides 14.1% enhancement in extraction efficiency. Consistent with the simulation, it is experimentally demonstrated that the GaInN LED employing the pyramid-patterned Ag reflector shows 13.9% higher light-output compared to the LED with a planar Ag reflector. In addition, the GaInN LED with pyramid reflector shows uniform light intensity due to current spreading beneath the SiO2 pyramid pattern. The enhancement is attributed to the appearance of an additional escape cone for light extraction, enabled by the change in direction of light rays reflected by the 3-dimensional pyramid reflector.