High performance near-ultraviolet flip-chip light-emitting diodes with distributed Bragg reflector

Il-Gyun Choi; Geun-Mo Jin; Jun-Cheon Park; Soo-Kun Jeon; Eun-Hyun Park

doi:10.1117/12.2185781

8 September 2015 High performance near-ultraviolet flip-chip light-emitting diodes with distributed Bragg reflector

Il-Gyun Choi, Geun-Mo Jin, Jun-Cheon Park, Soo-Kun Jeon, Eun-Hyun Park

Proceedings Volume 9571, Fourteenth International Conference on Solid State Lighting and LED-based Illumination Systems; 95710R (2015) https://doi.org/10.1117/12.2185781
Event: SPIE Optical Engineering + Applications, 2015, San Diego, California, United States

Abstract

We have fabricated the near-ultraviolet (NUV) flip-chip (FC) light-emitting diodes (LEDs) with the high external quantum efficiency (EQE) using distributed Bragg reflectors (DBRs) and compared with conventional FC-LED using silver (Ag) reflector. Reflectance of Ag is very high (90 ~ 95 %) at visible spectrum region, but sharply decrease at NUV region. Therefore we used DBR composed of two different materials which have high-index contrast, such as TiO₂ and SiO₂. However, to achieve high-performance NUV flip-chip LEDs, we used Ta₂O₅ instead of TiO₂ that absorbs lights of NUV region. Thus, we have designed a DBR composed of twenty pairs of Ta₂O₅ and SiO₂ using optical coating design software. The DBR designed by our group achieves a reflectance of ~99 % in the NUV region (350 ~ 500 nm), which is much better than Ag reflector. Optical power is higher than the Ag-LED up to 22 % @ 390 nm.

Citation Download Citation

Il-Gyun Choi, Geun-Mo Jin, Jun-Cheon Park, Soo-Kun Jeon, and Eun-Hyun Park "High performance near-ultraviolet flip-chip light-emitting diodes with distributed Bragg reflector", Proc. SPIE 9571, Fourteenth International Conference on Solid State Lighting and LED-based Illumination Systems, 95710R (8 September 2015); https://doi.org/10.1117/12.2185781

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