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Proceedings Paper

High-reflectance of hybrid reflector with distributed Bragg reflector and metal mirror for flip-chip ultra-violet light-emitting diodes
Author(s): Guang Yang; Huamao Huang; Hong Wang
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Paper Abstract

Three types of reflectors, including the distributed Bragg reflectors (DBRs), the first hybrid reflectors composed of DBR and Al mirror (DBR-Al), and the second hybrid reflectors composed of DBR, an additional low-refractive-index layer, and Al mirror (DBR-L-Al), were investigated by use of thin-film theory at the central wavelength of 300 nm for flip-chip ultra-violet light-emitting diodes (UV-LEDs). The number of DBR pairs and various high-refractive-index materials were studied. It is shown that the lossless materials with high refractive-index contrast should be selected for DBRs, and the DBR-Al hybrid reflectors provides higher reflectance comparing to DBRs. However, the Al mirror causes a sharp drop near the central wavelength and a blue shift of the peak position. These drawbacks can be suppressed by additional low-refractive-index layer attached on the Al mirror. In addition, the DBR-L-Al reflector leads to higher reflectivity and larger FWHM as compared to DBR-Al reflectors. By use of Monte Carlo ray tracing method, the light-extraction efficiency (LEE) for flip-chip UV-LEDs with (SiO2/ZrO2) 3 -SiO2-Al hybrid reflector or perfect mirror were simulated. The calculated LEE for the (SiO2/ZrO2) 3 -SiO2-Al hybrid reflector is 97 % of that for the perfect mirror. Moreover, the sharp drop in the angular reflectance spectrum of the (SiO2/ZrO2)3 -SiO2-Al hybrid reflector induces a slightly reduction of light intensity as compared to the perfect mirror.

Paper Details

Date Published: 18 December 2014
PDF: 6 pages
Proc. SPIE 9295, International Symposium on Optoelectronic Technology and Application 2014: Laser Materials Processing; and Micro/Nano Technologies, 92950A (18 December 2014); doi: 10.1117/12.2073098
Show Author Affiliations
Guang Yang, South China Univ. of Technology (China)
Huamao Huang, South China Univ. of Technology (China)
Hong Wang, South China Univ. of Technology (China)


Published in SPIE Proceedings Vol. 9295:
International Symposium on Optoelectronic Technology and Application 2014: Laser Materials Processing; and Micro/Nano Technologies
Guofan Jin; Songlin Zhuang; Jennifer Liu, Editor(s)

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