Improved light output from InGaN LEDs by laser-induced dumbbell-like air-voids

• Published in: Optics express Vol. 21; no. 26; pp. 32582 - 32588
• Main Authors: Zhang, Yiyun, Xie, Haizhong, Zheng, Haiyang, Dong, Peng, Yang, Hua, Yi, Xiaoyan, Wang, Guohong
• Format: Journal Article
• Language: English
• Published: United States 30.12.2013
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/oe.21.032582

We report inducing an array of dumbbell-like air-voids inside the sapphire substrate in InGaN-based light-emitting diodes (LEDs) to improve the light extraction from LED device by a picosecond (Ps) pulse laser. At an injection current of 100 mA, the light output power (LOP) of packaged LEDs with laser-induced air-voids can be improved by 24.7% compared with conventional LEDs. Far-field radiation pattern has verified that this great improvement in LOP is due to the light scattering occurred at the interface of sapphire/air-voids. Current-Voltage curves show that the laser processing of air-voids will not degrade the LED electrical properties. Furthermore, leakage current at a level of ~5 nA at -10V has demonstrated an enhancement in the LED electrical performance with laser-induced air-voids. Second focusing mechanism, which is originated in the local heating effect around the laser focus, has been proposed to explain the formation of dumbbell-like air-voids.