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 ${\hbox{TiO}}_{2}$ microsphere arrays. The optimization studies of the dipping method and rapid convective deposition (RCD) method were carried out for the deposition of ${\hbox{TiO}}_{2}$ microsphere arrays onto LEDs. The two-dimensional (2D) close-packed ${\hbox{TiO}}_{2}$ 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 ${\hbox{TiO}}_{2}$ microspheres via the two deposition methods.