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Huang YR, Chiu YC, Huang KC, Ting SY, Chiang PJ, Lai CM, Jen CP, Tseng SH, Wang HC. Light extraction efficiency enhancement of flip-chip blue light-emitting diodes by anodic aluminum oxide. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:1602-1612. [PMID: 29977694 PMCID: PMC6009532 DOI: 10.3762/bjnano.9.152] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/27/2018] [Indexed: 05/29/2023]
Abstract
We produced an anodic aluminum oxide (AAO) structure with periodic nanopores on the surface of flip-chip blue light-emitting diodes (FC-BLEDs). The nanopores had diameters ranging from 73 to 85 nm and were separated by distances ranging from approximately 10 to 15 nm. The light extraction efficiency enhancement of the FC-BLEDs subjected to different durations of the second pore-widening process was approximately 1.6-2.9%. The efficiency enhancement may be attributed to the following mechanism: periodic nanopores on the surface of FC-BLEDs reduce the critical angle of total reflection and effective energy transfer from a light emitter into a surface plasmon mode produced by AAO.
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Affiliation(s)
- Yi-Ru Huang
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan
| | - Yao-Ching Chiu
- Graduate Institute of Opto-Mechatronics, National Chung Cheng University, 168 University Rd., Min-Hsiung, Chia-Yi 62102, Taiwan
| | - Kuan-Chieh Huang
- R&D Center, Genesis Photonics Inc., No.5, Dali 3rd Rd., Shanhua Dist., Tainan City 74144, Taiwan
| | - Shao-Ying Ting
- R&D Center, Genesis Photonics Inc., No.5, Dali 3rd Rd., Shanhua Dist., Tainan City 74144, Taiwan
| | - Po-Jui Chiang
- Department of Electronic Engineering, National Kaohsiung University of Applied Sciences, No.415, Jiangong Rd., Sanmin Dist., Kaohsiung City 80778, Taiwan
| | - Chih-Ming Lai
- Department of Electronic Engineering, Ming Chuan University, Taoyuan 333, Taiwan
| | - Chun-Ping Jen
- Department of Mechanical Engineering, National Chung Cheng University, 168 University Rd., Min-Hsiung, Chia-Yi 62102, Taiwan
| | - Snow H Tseng
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan
| | - Hsiang-Chen Wang
- Graduate Institute of Opto-Mechatronics, National Chung Cheng University, 168 University Rd., Min-Hsiung, Chia-Yi 62102, Taiwan
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Baek S, Kang G, Shin D, Bae K, Kim YH, Kim K. Improvement of Light Extraction Efficiency in Flip-Chip Light Emitting Diodes on SiC Substrate via Transparent Haze Films with Morphology-Controlled Collapsed Alumina Nanorods. ACS APPLIED MATERIALS & INTERFACES 2016; 8:135-41. [PMID: 26690377 DOI: 10.1021/acsami.5b07783] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We demonstrate GaN-based flip-chip light emitting diodes (FC-LEDs) on SiC substrate achieving high extraction efficiency by simply attaching the optically transparent haze films consisting of collapsed alumina nanorods. Through controlled etching time of alumina nanorods, we obtain four types of films that have different morphologies with different optical transmittance and haze properties. We show that the light output power of the FC-LEDs with film, which has 95.6% transmittance and 62.7% haze, increases by 20.4% in comparison to the bare LEDs. The angular radiation pattern of the LEDs also follows the Lambertian emission pattern without deteriorating the electrical properties of the device. The improvement of light extraction is mainly attributed to the reduced total internal reflection (TIR) via efficient out-coupling of guided light from SiC substrate to air by collapsed alumina nanorod structures in the film. The high transparency of film and reduced Fresnel reflection via graded refractive index transition between the film and SiC substrate also contribute to the extraction enhancement of the device. We systematically investigate the influence of haze film's geometrical or optical properties on the extraction efficiency of FC-LEDs, and this study will provide a novel approach to enhance the performance of various optoelectronic devices.
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Affiliation(s)
- Seunghwa Baek
- School of Mechanical Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea
| | - Gumin Kang
- School of Mechanical Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea
| | - Dongheok Shin
- School of Mechanical Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea
| | - Kyuyoung Bae
- School of Mechanical Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea
| | - Yong Hyun Kim
- LED Convergence Research Center, LED R&D Division, Korea Photonics Technology Institute , 9, Chumdan venture-ro, 108 beon-gil, Buk-gu, Gwangju 61007, South Korea
| | - Kyoungsik Kim
- School of Mechanical Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea
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Okamoto T, Nishikawa J, Yanai H, Nakamura H, Takeuchi H, Kurai S, Akada JK, Sakaida I. In vitro bactericidal effects of near-ultraviolet light from light-emitting diodes on Helicobacter pylori. Scand J Gastroenterol 2013; 48:1484-6. [PMID: 24063529 DOI: 10.3109/00365521.2013.837953] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We investigated whether near-ultraviolet light emitted from light-emitting diodes (LEDs) effects Helicobacter pylori viability and whether this new method can potentially apply to eradication therapy. Three H. pylori strains were used for near-ultraviolet (UV) LED irradiation experiments. Viability of isolates exposed to near-UV light was compared with controls by counting colony forming units. A time-dependent bactericidal effect of near-UV light was definitely observed. LED irradiation with near-UV light showed effective bactericidal activity against H. pylori strains. Eradication therapy with LED might provide a new avenue of treatment in patients refractory to eradication due to antibiotic resistance and/or adverse effects of antibiotics.
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Affiliation(s)
- Takeshi Okamoto
- Department of Gastroenterology and Hepatology, Yamaguchi University Graduate School of Medicine , Yamaguchi , Japan
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Bulashevich KA, Karpov SY. Is Auger recombination responsible for the efficiency rollover in III-nitride light-emitting diodes? ACTA ACUST UNITED AC 2008. [DOI: 10.1002/pssc.200778414] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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