화학공학소재연구정보센터
Solid-State Electronics, Vol.89, 156-160, 2013
Enhancement of light extraction efficiency in sub-300 nm nitride thin-film flip-chip light-emitting diodes
We report on the improved light extraction efficiency of 287 nm small periphery AlGaN/AlGaN thin-film flip-chip (TFFC) light-emitting diodes (LEDs) fabricated using the laser lift-off technique. After sapphire substrate removal, the exposed AlN N-face was etched in a KOH solution. The result was a 1.5-fold increase in the TFFC device output power at 20 mA dc current injection, which was attributed to the AlN surface texturing. TFFC die encapsulation process produced an additional 1.34-fold enhancement of the emitted light power. More importantly, the encapsulated thin-film LEDs exhibited a similar reliability performance compared to encapsulated conventional FC LEDs processed from the same epiwafer, and with no noticeable degradation of the encapsulating material optical properties. (C) 2013 Elsevier Ltd. All rights reserved.