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Proceedings Paper

Improved light extraction of nitride-based flip-chip light-emitting diodes by forming air voids on Ar-implanted sapphire substrate
Author(s): Yu-Hsiang Yeh; Jinn-Kong Sheu; Ming-Lun Lee; Po-Cheng Chen; Yu-Chen Yang; Cheng-Hsiung Yen; Wei-Chih Lai
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Paper Abstract

GaN-based flip-chip light emitting diodes (FC-LEDs) with embedded air voids grown on a selective-area Arimplanted AlN/sapphire (AIAS) substrate was demonstrated in this study. The proposed FC LED with an embedded light scattering layer can destroy the light interference and thereby increase the LEE of GaN-based flip-chip LEDs. The epitaxial layers grown on Ar-implanted regions exhibited lower growth rates compared with those grown on implantation-free regions. Accordingly, air voids formed over the implanted regions after merging laterally grown GaN facet fronts. The light-output power of LEDs grown on AIAS was greater than that of LEDs grown on implantation free sapphire substrates. At an injection current of 700 mA, the output power of LEDs grown on AIAS was enhanced by 20% compared with those of LEDs without embedded air voids. The increase in output power was mainly attributed to the scattering of light around the air voids, which increased the probability of photons escaping from the LEDs. This study on FC LEDs with embedded light-scattering layer highlights the potential application of these LEDs as an alternative to conventional patterned sapphire substrates for improving the LEE of GaN/sapphire-based LEDs. Based on ray tracing simulation, if the height and the width of bottom of gaps were increased to 3 μm, the Lop could be enhanced over 60%.

Paper Details

Date Published: 25 September 2014
PDF: 6 pages
Proc. SPIE 9190, Thirteenth International Conference on Solid State Lighting, 91900Z (25 September 2014); doi: 10.1117/12.2060386
Show Author Affiliations
Yu-Hsiang Yeh, National Cheng Kung Univ. (Taiwan)
Jinn-Kong Sheu, National Cheng Kung Univ. (Taiwan)
Ming-Lun Lee, Southern Taiwan Univ. of Science and Technology (Taiwan)
Po-Cheng Chen, National Cheng Kung Univ. (Taiwan)
Yu-Chen Yang, National Cheng Kung Univ. (Taiwan)
Cheng-Hsiung Yen, National Cheng Kung Univ. (Taiwan)
Wei-Chih Lai, National Cheng Kung Univ. (Taiwan)


Published in SPIE Proceedings Vol. 9190:
Thirteenth International Conference on Solid State Lighting
Matthew H. Kane; Jianzhong Jiao; Nikolaus Dietz; Jian-Jang Huang, Editor(s)

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