發光二極體一般都以外部發光量的變化來探討其發光品質，本研究使用光學顯微鏡配合高倍數物鏡，聚焦至發光二極體內部觀察圖形化藍寶石基板對於發光二極體發光品質的影響。透過本光學顯微鏡系統可以得知，電流在發光二極體內部分佈並非相當的均勻，發光強度較強的區域集中在電極附近，隨著操作電流的上升，使光之出射臨界角變小，造成光集中從LED中間區域出射，使邊緣之發光強度較中央弱。而透過側面(side view)的觀測也可得知，不同形狀的圖形化藍寶石基板其周圍的發光分布也不盡相同，使用光線追跡模擬的結果也有一樣的情況。最後本研究針對各種不同形狀的圖形化藍寶石基板進行探討，發現圓錐形且深寬比在1.2左右的結構對出光效率會有最好的提升效果，而使用半球封膠透鏡配合覆晶式封裝結構的圖形化藍寶石基板發光二極體，其出光效率可達到62%，比未做任何結構的發光二極體提升了40%。透過本光學系統對發光二極體內部進行量測再配合模擬驗證，可以將發光二極體最真實的發光變化給呈現出來，對未來追求更高效率的發光二極體晶片提供參考與協助。

In general, the light emitting diodes (LEDs) are discussed its luminous quality by the variation of external light of LED. We use optical microscopy in combination of high magnification objective lens to focus on the internal regions of LED to investigate the influence of patterned sapphire substrate. Through the optical system we would know the current spreading in the interior regions of LED was not very uniform. The luminous intensity would stronger concentrate in the nearby electrode regions. As the operating current raised, the refractive index of gallium nitride would become larger, and the critical angle of total reflection would be smaller. This phenomenon caused the light would only emit from the middle regions of LED and the luminous intensity weaker on the edges. Through the side view can also be observed that different shapes of patterned sapphire substrate caused the different light emission, and the ray tracing simulation display the close result. Finally, we focus on different shapes of patterned sapphire substrates. We found that the conical shape which aspect ratio = 1.2 has the best effect to enhance the extraction efficiency. Patterned sapphire substrates LED which use hemispherical lens with sealed plastic and flip-chip package structure can reach the light extraction efficiency to 62%, 40% higher than that without any structure LEDs. Apply this system to measure in the internal regions of LED, the truly influence of the patterned sapphire substrate effect on LED would be performed. For designing greater efficiency light-emitting diode chip provides reference and assistance in the future.

[1] R.Zheng, "Luminous Efficiency and Color Rending of Phosphor-Coverted
White LEDs", Journal of Light & Visual Environment, vol. 32(2), pp. 230-
233, 2008.
[2] E. F. Schubert, Light-Emitting Diodes, 2nd ed. (Cambridge University
Press Cambridge, 2006).
[3] 李農, 楊燕, LED照明手冊, 全華科技圖書有限公司 pp.8~12, 2012.
[4] 史光國, 半導體發光二極體及固態照明, 全華科技圖書有限公司, pp.1-1~1-30, 200.
[5] 劉博文, 光電元件導論, 全威圖書有限公司.
[6] Wang.S.C., "Internal Quantum Efficiency Measurement in InGaN/GaN UV LEDs
with Patterned Sapphire Substrate by Photoluminescence and
Electroluminescence Method", Conference of Laser and Electro-Optics
(CLEO) and Quantum Electronics and Laser Science Conference (QELS), 2010.
[7] X.H. Wang, P.T. Lai and H.W. Choi., "Design and performance of LEDs with
circular geometry", Physica Status solidi C7, No.7-8,2144-2147, 2010.
[8] W.Y. Fu, K.N. Hui, X.H. Wang, K.K.Y. Wong, P.T. Lai and H.W.Choi,
"Geometrical Shaping of InGaN Light-emitting Diodes by Laser
Micromachining", IEEE Photonics Technology Letters, VOL. 21, NO. 15 ,
2009
[9] Osram Opto Semiconductors, http://www.osram-os.com
[10] E.Yablonovitch, "Inhibited spontaneous emission in solid-state physics
and electronics", Journal of Physics Revolution Letter 58, 2059−2062,
1987.
[11] Hongwei Liu, Qiang Kan, Chunxia Wang, Feng Yu, Xingsheng Xu and Hongda
Chen, "Light extraction of GaN LEDs with 2-D photonic crystal
structure", Chinese Optics Letters vol. 7, No. 10, 2009.
[12] V. Harle, B. Hahn, J. Baur, M.Fehrer, A. Weimar, S. Kaiser, D. Eisert,
F. Eberhard and A. Plossl, S. Bader, "Advanced Technologies for high
efficiency GaInN LEDs for solid state lighting", Proceeding of SPIE
vol.5187 pp.34-40, 2004.
[13] C. M. Tsai, J. K. Sheu, W. C. Lai, Y. P. Hsu, P. T. Wang, C. T. Kuo, C.
W. Kuo, S. J. Chang, and Y. K. Su, "Enhanced output power in GaN-based
LEDs with naturally textured surface grown by MOCVD," IEEE Electron
Device Letters, vol. 26, pp. 464-466, 2005.

[14] X. Guo and E. F. Schubert, "Current crowding in GaN/InGaN light emitting
diodes on insulating substrates," Journal of Applied Physics, vol. 90,
p. 4191, 2001.
[15] S. D. Lester, F. A. Ponce, M. G. Craford, and D. A. Steigerwald,
"Highdislocation densities in high efficiency GaN-based light-emitting
diodes," Applied Physics Letters, p. 1249, 1995.
[16] A. Usui, H. Sunakawa, A. Sakai, and A. A. Yamaguchi, "Thick GaN
epitaxial growth with low dislocation density by hydride vapor phase
epitaxy," Japanese Journal of Applied Physics, Part 2: Letters, vol. 36,
pp. L899-L902, 1997.
[17] 張靜宜, "側向磊晶技術成長氮化鎵之研究", in 材料科學與工程學系:國立成功大學,(2005).
[18] 紀國鐘、蘇炎坤 ，《光電半導體技術手冊》，經濟部，民國91年。
[19] W.K. Wanga, D.S. Wuua,_, S.H. Lina, S.Y. Huanga, K.S. Wena and R.H.
Horng, "Growth and characterization of InGaN-based light-emitting diodes
on patterned sapphire substrates", Journal of Physics and Chemistry of
Solids vol.69 pp.714-718, 2008.
[20] Jae-Hoon Lee, Dong-Yul Lee, Bang-Won Oh and Jung-Hee Lee, "Comparison
of InGaN-Based LEDs Grown on Conventional Sapphire and Cone-Shape-
Patterned Sapphire Substrate", IEEE Transactions Electron Devices vol.
57 No. 1, 2010.
[21] Chia-Ta Chang, Shih-Kuang Hsiao, Edward Yi Chang, Senior Member, IEEE,
Yu-Lin Hsiao, Jui-Chien Huang,Chung-Yu Lu, Huang-Choung Chang, Kai-Wen
Cheng, and Ching-Ting Lee, "460-nm InGaN-Based LEDs Grown on Fully
Inclined Hemisphere-Shape-Patterned Sapphire Substrate With
Submicrometer Spacing, " IEEE Photonics Technology Letters, vol . 21,
NO. 19, 2009.
[22] Ching-Hsueh Chiu, Lung-Hsing Hsu, Chia-Yu Lee, Chien-Chung Lin, Bo-Wen
Lin, Shang-Ju Tu, Yan-Hao Chen, Che-Yu Liu, Wen-Ching Hsu, Yu-Pin Lan,
Jinn-Kong Sheu, Tien-Chang Lu, Gou-Chung Chi, Hao-Chung Kuo and Shing-
Chung, "Light Extraction Enhancement of GaN-Based Light-Emitting Diodes
Using Crown-Shaped Patterned Sapphire Substrates", IEEE Photonics
Technology Letters, vol. 24, NO. 14, 2012.
[23] Joonhee Lee, Dong-Ho Kim 1, Jaehoon Kim and Heonsu Jeon, "GaN-based
light-emitting diodes directly grown on sapphire substrate with
holographically generated two-dimensional photonic crystal patterns",
Current Applied Physics 9, vol.9 pp.633-635, 2009.

[24] Akihiro Ishihara, Ryonsake Kawai, Thukasa Kitano, Atushi
Suzaki,Toshiyuki Kondo, Motoaki Iwaya, Hiroshi Amano, Satoshi
Kamiyamaand Isamu Akasaki, "Growth and charaterication of GaN grown on
moth-eye patterned sapphire substrate", Physica Status Solidi C 7, No.7-
8,2056-2058, 2010
[25] Y. K. Su, J. J. Chen, C. L. Lin, and C. C. Kao, "Structural analysis of
nitride-based LEDs grown on micro- and nano-scale patterened sapphire
substrate", Physica Status Solidi C 7, No. 7–8, 1784– 1786 , 2010
[26] 張博揚, "濕蝕刻圖案化藍寶石基板對氮化鎵發光二極體特性影響之研究", in 光電工程所: 長庚
大學 (2009).
[27] H. Gao, F. Yan, Y. Zhang, J. Li, Y. Zeng, and G. Wang, "Enhancement of
the light output power of InGaN/GaN light-emitting diodes grown on
pyramidal patterned sapphire substrates in the micro- and nanoscale,"
Journal of Applied Physics, vol. 103, pp. 014314-5, 2008.
[28] Yu-Chung Chen, Feng-Ching Hsiao, Bo-Wen Lin, Ban-Ming Wang, Yew-Chung
Sermon Wu and Wen-Ching Hsu, "The Formation and the Plane Indices of
Etched Facets of Wet Etching Patterned Sapphire substrate", Journal of
Electrochemical Society Vol.159 issue.6 pp.362-366, 2009
[29] Y. J. Lee, H. C. Kuo, T. C. Lu, B. J. Su, and S. C. Wang, "Fabrication
and Characterization of GaN-Based LEDs Grown on Chemical Wet-Etched
Patterned Sapphire Substrates", Journal of The Electrochemical Society,
153 _12_ G1106-G1111, 2006.
[30] Yan Fawang, Gao Haiyang and Zhang Yang "High-efficiency GaN-basedblue
LEDs grown on nano-patterned sapphire substrates for solid-state
lighting", Proceeding of SPIE 6841:684103-1-7, 2007
[31] Chang-Chi Pan, Chi-Hsun Hsieh, Chih-Wei Lin, and Jen-Inn Chyi, "Light
output improvement of InGaN ultraviolet light-emitting diodes by using
wet-etched stripe-patterned sapphire substrates", Journal of Applied
Physics 102, 084503; doi: 10.1063/1.2798537, 2007
[32] Stephen Y. Chou, Peter R. Krauss, and Preston J. Renstrom, "Nanoimprint
lithography", Journal of Vacuum Science & Technology B 14, 4129, 1996
[33] Chien-Chih Kao, Yan-Kuin Su, Chuing-Liang Lin and Jian-Jhong Chen, "The
aspect ratio effects on the performances of GaN-based light-emitting
diodes with nanopatterned sapphire substrates", Applied Physics Letters
97, 023111, 2010
[34] C. Griffin, E. Gu, H. W. Choi, C. W. Jeon, J. M. Girkin, M. D. Dawson,
and G. McConnell, "Beam divergence measurements of InGaN/GaN micro-array
light-emitting diodes using confocal microscopy," Applied Physics
Letters, vol. 86, pp. 041111-041111-3, 2005.
[35] P. Davidovits and M. D. Egger, "Scanning Laser Microscope," Nature, vol.
223, pp. 831-831, 1969.
[36] L. Kuna, C. Sommer, E. Zinterl, F. P. Wenzl, P. Pachler, P. Hartmann, S.
Tasch, and G. Leising, "Confocal microscopy as a tool for the study of
the emission characteristics of high-power LEDs," Applied Physics B:
Lasers and Optics, vol. 91, pp. 571-577, 2008.
[37] Tae Su Oh, Hyun Jeong, Yong Seok Lee, Ah Hyun Park, Tae Hoon Seo, Hun
Kim, Kang Jea Lee, Mun Seok Jeong and Eun-Kyung Suh1, "Light outcoupling
effect in GaN light-emitting diodes via convex microstructures
monolithically fabricated on sapphire substrate", Optics Express.
19(10):9385-91. doi: 10.1364/OE.19.009385. , 2012
[38] "A Guide to Integrating Sphere Theory and Applications,"
http://www.labsphere.com/data/userFiles/A%20Guide%20to%20Integrating%20Sphere%20Theory&Apps.pdf, p. 3.
[39] J. W. Pan and C. S. Wang, "Light extraction efficiency of GaN-based LED
with pyramid texture by using ray path analysis," Optics Express 20,
A630-A640 2012.
[40] 李宗憲, "氮化鎵發光二極體之光萃取效率分析與晶片設計", in 光電科學研究所: 中央大學
(2008).
[41] Optical Research Associates Lighttools,
http://www.opticalres.com/lt/ltprodds_f.html
[42] Yen-Kuang Kuo, Jih-Yuan Chang and Miao-Chan Tsai, "Enhancement inhole-
injection efficiency of blue InGaN light-emitting diodes from
reducedpolarization by some specific designs for the electron blocking
layer", Optics Letters vol.35 No.19, 2010.
[43] C. Mo, W. Fang, Y. Pu, H. Liu, and F. Jiang, "Growth and
characterization of InGaN blue LED structure on Si(111) by MOCVD,"
Journal of Crystal Growth, vol. 285, pp. 312-317, 2005.
[44] R.-H. Horng, C.-E. Lee, C.-Y. Kung, S.-H. Huang, and D.-S. Wuu, "High-
Power AlGaInP Light-Emitting Diodes with Patterned Copper Substrates by
Electroplating," Japanese Journal of Applied Physics, vol. 43, pp. L576-
L578, 2004.
[45] 徐才竣, "以光學顯微鏡量測熱效應對發光二極體之影響", in 電子工程所:國立台灣科技大學
(2008)