Improvement of Light Extraction From Patterned Polymer Encapsulated GaN-Based Flip-Chip Light-Emitting Diodes by Imprinting

To improve surface light extraction of GaN-based flip-chip light-emitting diodes (FC-LEDs), we employed an imprint approach of thermosetting polymer for patterning microscale surface grating on the polymer encapsulant. One-dimensional (1-D) and two-dimensional (2-D) taper-like polymer gratings with...

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Bibliographic Details
Published in:IEEE photonics technology letters 2007-11, Vol.19 (22), p.1840-1842
Main Authors: Bao, Kui, Kang, Xiang Ning, Zhang, Bei, Dai, Tao, Xiong, Chang, Ji, Hang, Zhang, Guo Yi, Chen, Yong
Format: Article
Language:English
Subjects:
Analytical models
Backplanes
Diffraction gratings
Encapsulation
Extraction
Gallium nitride
Gallium nitrides
Gratings
Light emitting diodes
light-emitting diodes (LEDs)
nano technology
Optical films
Organic light emitting diodes
Patterning
Performance evaluation
Polymer films
Simulation
Two dimensional
Two dimensional displays
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Summary:To improve surface light extraction of GaN-based flip-chip light-emitting diodes (FC-LEDs), we employed an imprint approach of thermosetting polymer for patterning microscale surface grating on the polymer encapsulant. One-dimensional (1-D) and two-dimensional (2-D) taper-like polymer gratings with a period of 6 mum were successfully realized on encapsulant above the sapphire backplane of GaN LED. By adopting the 1-D and 2-D taper-like grating encapsulant, the improvement of light extraction from the 1 mm times 1 mm FC-blue LED with a reflective Ag film on the p-side was about 18.5% and 31.9% compared to the LED encapsulated by flat polymer, respectively. To evaluate the concept of a diffraction grating in enhancement of light extraction, we performed a simulation of diffraction based on 1-D rigorous coupled wave analysis with the supporting experiments.
ISSN:1041-1135
1941-0174
DOI:10.1109/LPT.2007.908731