Light extraction efficiency enhancement of III-nitride light-emitting diodes by using 2-D closepacked TiO2 microsphere arrays

Abstract—The enhancement of light extraction efficiency of InGaN quantum well light emitting diodes (LEDs) was achieved by employing the refractive index matched TiO microsphere arrays. The optimization studies of the dipping method and rapid convective deposition (RCD) method were carried out for the deposition of TiO microsphere arrays onto LEDs. The two-dimensional (2D) close-packed TiO microsphere arrays were deposited by the using optimized conditions of the dipping and RCD methods, respectively. The light extraction efficiencies of LEDs under electrical injection were enhanced by 1.8–1.9 times by utilizing 520-nm diameter amorphous and anatase TiO microspheres via the two deposition methods. Index Terms—III-Nitride, light-emitting diodes, light extraction efficiency, refractive index matching, TiO microspheres. I