Light Extraction Efficiency Enhancement of III-Nitride Light-Emitting Diodes by Using 2-D Close-Packed ${\hbox {TiO}}_{2}$ Microsphere Arrays

The enhancement of light extraction efficiency of InGaN quantum well light emitting diodes (LEDs) was achieved by employing the refractive index matched TiO₂ microsphere arrays. The optimization studies of the dipping method and rapid convective deposition (RCD) method were carried out for the deposition of TiO₂ microsphere arrays onto LEDs. The two-dimensional (2D) close-packed TiO₂ 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 TiO₂ microspheres via the two deposition methods.