Fabrication and characterization of resonant-cavity light emitting diodes for white lighting
碩士 === 長庚大學 === 電子工程學系 === 99 === Due to the large difference in refractive index between GaN material and air, most of light cannot escape from the semiconductor and gradually be absorbed within InGaN light-emitting diode (LED). To fabricate the RC-LEDs in this study, the thickness of the sapphire...
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ndltd-TW-099CGU054280572015-10-13T20:27:50Z http://ndltd.ncl.edu.tw/handle/51814484964211592736 Fabrication and characterization of resonant-cavity light emitting diodes for white lighting 共振腔白光發光二極體之研製與特性分析 Yu Sheng Lee 李育勝 碩士 長庚大學 電子工程學系 99 Due to the large difference in refractive index between GaN material and air, most of light cannot escape from the semiconductor and gradually be absorbed within InGaN light-emitting diode (LED). To fabricate the RC-LEDs in this study, the thickness of the sapphire substrate was thinned by lapping and polishing. A distributed Bragg reflector (DBR) consisted of alternating λ/4-thick Ta2O5 and SiO2 and a high-reflectivity metal layer (Al) was respectively coated onto the top and bottom surface of the LEDs to form a Fabry-Perot cavity. As a result, with increasing the number of DBR pair the amount of emitted light is reduced due to increased optical loss in the cavity. Actually, the optical cavity length of LED is too long (~90um) so that the probability of light being absorbed by the material is increased. To improve the device performance, it is desired to reduce the cavity length. Finally, RC-LED fabricated with one pair DBR along with the bottom metal reflectors and normal LED were respectively used to form a white light by placing a fluorescent layer on top of these devices. Experimentally, the normal LED operated in a direct current 20mA was used to act as a reference light source. With variation in fabrication parameter of the fluorescent layer, such as thick and composition, the color of light emitted by an LED can be tuned to the color coordinate of white light (0.33, 0.33). Because the light output power of RC-LED larger than normal LED, correlated color temperature is larger, too. C. L. Tsai 蔡家龍 2011 學位論文 ; thesis 93 |
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碩士 === 長庚大學 === 電子工程學系 === 99 === Due to the large difference in refractive index between GaN material and air, most of light cannot escape from the semiconductor and gradually be absorbed within InGaN light-emitting diode (LED).
To fabricate the RC-LEDs in this study, the thickness of the sapphire substrate was thinned by lapping and polishing. A distributed Bragg reflector (DBR) consisted of alternating λ/4-thick Ta2O5 and SiO2 and a high-reflectivity metal layer (Al) was respectively coated onto the top and bottom surface of the LEDs to form a Fabry-Perot cavity. As a result, with increasing the number of DBR pair the amount of emitted light is reduced due to increased optical loss in the cavity. Actually, the optical cavity length of LED is too long (~90um) so that the probability of light being absorbed by the material is increased. To improve the device performance, it is desired to reduce the cavity length.
Finally, RC-LED fabricated with one pair DBR along with the bottom metal reflectors and normal LED were respectively used to form a white light by placing a fluorescent layer on top of these devices. Experimentally, the normal LED operated in a direct current 20mA was used to act as a reference light source. With variation in fabrication parameter of the fluorescent layer, such as thick and composition, the color of light emitted by an LED can be tuned to the color coordinate of white light (0.33, 0.33). Because the light output power of RC-LED larger than normal LED, correlated color temperature is larger, too.
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C. L. Tsai |
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C. L. Tsai Yu Sheng Lee 李育勝 |
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Yu Sheng Lee 李育勝 |
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Yu Sheng Lee 李育勝 Fabrication and characterization of resonant-cavity light emitting diodes for white lighting |
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Yu Sheng Lee |
title |
Fabrication and characterization of resonant-cavity light emitting diodes for white lighting |
title_short |
Fabrication and characterization of resonant-cavity light emitting diodes for white lighting |
title_full |
Fabrication and characterization of resonant-cavity light emitting diodes for white lighting |
title_fullStr |
Fabrication and characterization of resonant-cavity light emitting diodes for white lighting |
title_full_unstemmed |
Fabrication and characterization of resonant-cavity light emitting diodes for white lighting |
title_sort |
fabrication and characterization of resonant-cavity light emitting diodes for white lighting |
publishDate |
2011 |
url |
http://ndltd.ncl.edu.tw/handle/51814484964211592736 |
work_keys_str_mv |
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