In this study, pulsed lasers were used to fabricate micro/nano structures on the transparent conducting oxide (TCO) layers of the light emitting diodes (LEDs) to destroy the total internal reflectionat TCO/air and enhance the light extraction efficiency. The formation of laserinduced periodic surface structures (LIPSS) depends on the pulsed duration. For nanosecond laser, LIPSS was attributed to the interference of surface scattering wave and incident laser, but second harmonic wave generated from the interference of surface scattering and surface plasma induces ripples for the femtosecond laser. This study showed that light-emitting efficiency increases with surface roughness by femtosecond laser, and achieved an improvement of 16.46 %. But the forward voltage is also higher through femtosecond laser processing, meaning the laser fluence damaged the p-GaN. However, light output power enhanced to 24% and the forward voltage was not changed after nanosecond laser processing, this showed that flat-top beam of nanosecond laser was only fabricate ripple structure but not damaged the electrical property of LED.
|Original language||Chinese (Traditional)|
|Publication status||Published - Jan 2011|