A patterned double-layer indium-tin oxide (ITO), including the first unpatterned ITO\nlayer serving as current spreading and the second patterned ITO layer serving as light extracting,\nwas applied to obtain uniform current spreading and high light extraction efficiency (LEE)\nof GaN-based ultraviolet (UV) light-emitting diodes (LEDs). Periodic pinhole patterns were formed\non the second ITO layer by laser direct writing to increase the LEE of UV LED. Effects of interval of\npinhole patterns on optical and electrical properties of UV LED with patterned double-layer ITO\nwere studied by numerical simulations and experimental investigations. Due to scattering out of\nwaveguided light trapped inside the GaN film, LEE of UV LED with patterned double-layer ITO\nwas improved as compared to UV LED with planar double-layer ITO. As interval of pinhole patterns\ndecreased, the light output power (LOP) of UV LED with patterned double-layer ITO increased.\nIn addition, UV LED with patterned double-layer ITO exhibited a slight degradation of current\nspreading as compared to the UV LED with a planar double-layer ITO. The forward voltage of UV\nLED with patterned double-layer ITO increased as the interval of pinhole patterns decreased.
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