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Proceedings Paper

Improvement of light extraction from micro-pattern encapsulated GaN-based LED by imprinting
Author(s): Kui Bao; Bei Zhang; XiangNing Kang; Tao Dai; Chang Xiong; GuoYi Zhang; Yong Chen
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Paper Abstract

We have demonstrated an improvement of light extraction from GaN based flip-chip LEDs by patterning encapsulant. Two dimensional (2D) micron-scale patterns of encapsulant were realized by using imprint technique of thermosetting polymer. This approach has several advantages such as technical simplification, low cost and freedom of material choice. In this work, we fabricated 2D micron-scale patterns with the triangular or sinusoidal profiles on the polymer encapsulated GaN-based flip-chip LEDs. The enhancement factors of light extraction of GaN LEDs with the patterned encapsulant comparing to the flat encapsulated LEDs are about 32% and 47% corresponding to the triangular and sinusoidal profiles, respectively. To evaluate the concept of a diffraction grating in enhancement of light extraction, we performed a simulation of diffraction based on simplified one-dimensional (1D) rigorous coupled wave analysis (RCWA). The calculation reveals that the grating of sinusoidal profile has greater transmittance than that of triangular profile which is in the same trend with the experimental results. These results provide a guideline for improvement of the LED light extraction.

Paper Details

Date Published: 13 February 2008
PDF: 8 pages
Proc. SPIE 6910, Light-Emitting Diodes: Research, Manufacturing, and Applications XII, 69100N (13 February 2008); doi: 10.1117/12.763285
Show Author Affiliations
Kui Bao, Peking Univ. (China)
Bei Zhang, Peking Univ. (China)
XiangNing Kang, Peking Univ. (China)
Tao Dai, Peking Univ. (China)
Chang Xiong, Peking Univ. (China)
GuoYi Zhang, Peking Univ. (China)
Yong Chen, Peking Univ. (China)
Lab. de Photonique et Nanostructures (France)

Published in SPIE Proceedings Vol. 6910:
Light-Emitting Diodes: Research, Manufacturing, and Applications XII
Klaus P. Streubel; Heonsu Jeon, Editor(s)

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