Improved External Quantum Efficiency and Controlled Light Distribution for Light-Emitting Diodes with Cone Array Composed of SiO_xN_y

摘要

We investigated the effect of the refractive index of a SiO_xN_y cone array on device performance for light-emitting diodes (LEDs). LEDs were fabricated on a sapphire substrate with a cone array composed of SiO_xN_y. The refractive index of the SiO_xN_y was varied from 1.46 to 2.06. The SiO_xN_y cone array was found to improve light extraction efficiency, which was also calculated by a ray-tracing method. The maximum external quantum efficiency was obtained for a refractive index of 2.06. Moreover, the light distribution of the LED can be controlled by adjusting the refractive index of the SiO_xN_y cone array.