本論文針對發光二極體(LEDs) 的光取出與散熱問題進行研究。本論文提出兩種不同的方法來增加發光二極體的光取出強度。另一方面本論文提出利用電鍍的技術來改善高功率發光二極體的散熱問題。
本論文為了改善發光二極體的光取出的問題，提出兩種可以有效增加光取出的方法，並分成兩部份來探討，第一部份，我們發現現今被用來切割發光二極體晶粒的雷射劃線(laser scribing)技術，不僅不會造成發光二極體的側面光取出強度,甚至於可以經由優化雷射劃線的參數進一步增加發光二極體的側面光取出強度。本論文的研究結果顯示，優化後的雷射劃線參數可以增加發光二極體大約12%的光取出強度，本論文證明增加側光取出強度的重要關鍵是因為雷射畫線參數的優化，而使得藍寶石基板的側壁變的更加地粗糙，粗糙的側壁降低了光在藍寶石基板/空氣的界面發生全反射(total internal reflection)的機率。第二部分，本論文為了改善發光二極體的電極吸光效應,因此本論文改變了傳統發光二極體的電極結構。本論文將一般常用來作為發光二極體的金(gold)電極改為銀(silver)。由於銀的反射率(90%)遠大於金的反射率(55%)，因此有助於改善發光二極體的電極吸光效應。由本論文的實驗結果顯示，比較銀電極與金電極所製作而成的發光二極體，可以明顯比較出使用銀作為電極的發光二極體的光取出強度相較於使用金電極的發光二極體增加約15%。另一方面，隨著黃金價格十年來不斷高漲，本論文估算結果顯示將發光二極體的金電極改用銀電極可以大幅降低生產成本。
在高功率發光二極體的研究範疇中，我們提出以電鍍銅的技術來取代封裝結構中用來固定晶片的膠，因為膠的熱傳導係數通常遠小於銅。在傳統的發光二極體結構中, 固晶膠是用來將發光二極體晶片固定在散熱座( heat sink)或是支架(lead frame)上的材料，然而卻因為它的熱傳導係數低而造成高功率發光二極體的散熱能力受到限制，因而使得發光二極體的性能在高電流條件操作下受到嚴重的損壞。本論文為了改善由固晶膠所造成的散熱問題因此改以電鍍銅層來取代封裝結構中的固晶膠體，實驗結果顯示不僅可以有效地改善高功率發光二極體的散熱問題，並且大幅地增加元件的光輸出功率。

In this thesis, we focus our research on light extraction and heat dissipation of light emitting diodes (LEDs). We proposed two different methods for light extraction, while also using electroplating technology to improve heat dissipation of high power LEDs.
The light extraction research was divided into two parts. In the first part, we discovered that laser scribing not only failed to lower LED side light extraction, but actually increased it through the optimization of laser scribing parameters. The results showed that laser scribing increased light extraction of LEDs by about 12%. One of the critical elements is that the LED side wall increased in roughness, thus lowering the chance of total internal reflection at the sapphire/air interface. In the second part of our research, we changed the conventional electrode composition of LEDs in general common-saver from gold-based to silver-based electrodes to improve the absorption of light by electrodes. Results from the experiment showed that, when compared to gold-based electrodes, silver-based electrodes not only significantly increased light extraction of LEDs by approximately 15%, but can also significantly reduced the manufacturing cost of LEDs.
When studying high power LED heat dissipation, we recommend that electroplated copper be used to replace resin in package structure to overcome the characteristic of resin as a low thermal conductivity material. In conventional high power LED package structure, resin is used to affix LEDs to the heat sink (lead frame). But since resin’s low thermal conductivity limit the heat dissipation ability of high power LEDs and can cause major damage to LED performances during high current conduction operation, using electroplating copper in place of resin in package structure can effectively improve the heat dissipation problem, and thus increase the output power of LEDs.

[1]G. Desriau, “Scintillations of zinc sulfides with alpha-rays,” J. Chiie Physique, vol. 33, p.587, 1936.
[2]Zh. I. Alferov, V. M. Andre, D. Z. Garbuzov, and Rumyantsev, Sov. Phys.—Semicond., vol. 9, p. 305, 1975.
[3]J. Nishizawa and K. Suto, “Minority-carrier lifetime measurements of efficient GaAlAs p-n heterojunctions ,” J. Appl. Phys., vol. 48, pp. 3484, 1977.
[4]K. Kobayashi, S. Kawata, A. Gomyo, I. Hino, and T. Suzuki, “Room-temperature cw operation of AlGaInP double-heterosturcture visible lasers,” Electron. Lett., vol. 21, p. 931, 1985.
[5]K. Itaya, M. Ishikawa, and Y. Uematsu, “636 nm room temperature cw operation by heterobarrier blocking structure InGaAlP laser diodes,” Electron. Lett., vol. 26, p. 839, 1990.
[6]K. H. Huang and T. P. Chen, “Light-emitting diode structure,” U.S. Patent 5,661,742, 1997.
[7]H. Sugawara, K. Itaya, M. Ishikawa and G. Hatakoshi, “High-efficiency InGaAlP visible light-emitting diodes,” Jpn. J. Appl. Phys., vol. 31, pp. 2446-2451, vo. 8, 15 August 1992.
[8]C. P. Kuo, R. M. Fletcher, T. D. Osentowski, M. C. Lardizabal, M. G. Craford, and V. M. Robbins, “High performance AlGaInP visible light-emitting diodes,” Appl. Phys. Lett., vol.57, pp. 2937-2939, 1990.
[9]H. Sugawara, M. Ishikawa, N. Yoshihiro, Y. Nishikawa, and S. Naritsuka, “Semiconductor light emitting device,” U.S. Patent 5 048 035, Sep. 10, 1991.
[10]S. J. Chang, C. S. Chang, Y. K. Su, P. T. Chang, Y. R. Wu, K. H. Huang and T. P. Chen, “AlGaInP multiquantum well light-emitting diodes,” IEE Proceedings—Optoelectronics, vol. 144, p. 1, 1997.
[11]K. H. Huang and T. P. Chen, “Light-emitting diode structure,” U.S. Patent 5,661,742, 1997.
[12]F. A. Kish, F. M. Steranka, D. C. DeFevere, D. A. Vanderwter, K. G. Park, C. P. Kuo, T. D. Osentowski, M. J. Peanasky, J. G. Yu, R. M. Fletcher, D. A. Steigerwald, M. G. Craford, and V. M. Robbins, “Very high-efficiency semiconductor wafer-bonded transparent-substrate (AlxGa1–x)0.5In0.5P/GaP light-emitting diodes,” Appl. Phys. Lett., vol. 64, pp. 2839-2841, May 23, 1994.
[13]D. A. Steigerwald, J. C. Bhat, D. Collins, R. M. Fletcher, M. O. Holcomb, M. J. Ludowise, Member, IEEE, P. S. Martin, and S. L. Rudaz, “Illumination with solid state lighting technology,” IEEE J. Select. Topics Quantum Electron., vol. 8, pp. 310-320, 2002.
[14]H. P. Maruska, and J. J. Tietjen, “The preparation and properties of vapour-deposited single-crystal-line GaN,” Appl. Phys. Lett., vol. 15, p. 327, 1969.
[15]H. Amano, M. Kito, K. Hiramatsu and I. Akasaki, “P-Type conduction in Mg-doped GaN treated with low-energy electron beam irradiation (LEEBI),” Jpn. J. Appl. Phys. Part 2, vol. 28, pp. L2112-L2114, 1989.
[16]S. Nakamura, N. Iwasa, and M. Senoh, “Method of manufacturing p-type compound semiconductor,” U.S. Patent 5,306,662, 1994.
[17]C. Huh, K. S. Lee, E. J. Kang, and S. J. Park, “Improved light-output and electrical performance of InGaN-based light-emitting diode by microroughening of the p-GaN surface,” J. Appl. Phys., vol. 93, pp. 9383–9286, 2003.
[18]R. Windisch, B. Dutta, M. Kuijk, A. Knobloch, S. Meinlschmidt, S. Schoberth, P. Kiesel, G. Borghs, G. H. Dohler, and P. Heremans, “40% efficient thin film surface textured light emitting diodes by optimization of natural lithography,” IEEE Trans. Electron Devices, vol. 47, pp. 1492–1498, July 2000.
[19]Hsu, Y. P., Chang, S. J., Su, Y. K., Sheu, J. K., Lee, C. T., Wen, T. C., Wu, L. W., Kuo, C. H., Chang, C. S., and Shei, S. C., "Lateral epitaxial patterned sapphire InGaN/GaN MQW LEDs," Journal of Crystal Growth, vol. 261, no. 4, pp. 466-470, 2004.
[20]Tsai, C. M., Sheu, J. K., Lai, W. C., Hsu, Y. P., Wang, P. T., Kuo, C. T., Kuo, C. W., Chang, S. J., and Su, Y. K., "Enhanced output power in GaN-based LEDs with naturally textured surface grown by MOCVD," IEEE Electron Device Letters, vol. 26, no. 7, pp. 464-466, 2005.
[21]Tsai, P.C., Chen, W.R., Su, Y.K., Huang, C.Y., “Enhanced light output of InGaN LEDs with a roughened p-GaN surface using different TMGa flow rates in p-AlGaN layer” APPLIED SURFACE SCIENCE, 256(22), 6694-6698, SEPTEMBER 2010.
[22]D. S. Kuo, S. J. Chang, C. F. Shen, T. C. Ko, T. K. Ko and S. J. Hon, "Nitride-based LEDs with oblique sidewalls and a light guiding structure", Semicond. Sci. Technol., Vol. 25, No. 5, Art. no. 055010, May 2010.
[23]D. S. Kuo, S. J. Chang, T. K. Ko, C. F. Shen, S. J. Hon and S. C. Hung, "Nitride-based LEDs with phosphoric acid etched undercut sidewalls", IEEE Photon. Technol. Lett., Vol. 21, No. 8, pp. 510-512, April 2009.
[24]W. S. Wong, M. Kneissl, P. Mei, D. W. Treat, M. Teepe, and N. M. Johnson,” Continuous-wave InGaN multiple-quantum-well laser diodes on copper substrates,” Appl. Phys. Lett., Vol. 78, pp. 1198-1200, 2001.
[25]Chen, W.S. , Shei, S.C., Chang, S.J., Su, Y.K., Lai, W.C., Kuo, C.H., Lin, Y.C., Chang, C.S., Ko, T.K., Hsu, Y.P., Shen, C.F. ,"Rapid thermal annealed InGaN/GaN Flip-Chip LEDs," IEEE Trans. on Electron Devices, Vol. 53, pp. 32-36, 2006
[26] J. J. Wierer, D. A. Steigerwald, M. R. Krames, J. J. O'Shea, M. J. Ludowise, G. Christenson, Y.-C. Shen, C. Lowery, P. S. Martin, S. Subramanya, W. Götz, N. F. Gardner, R. S. Kern, and S. A. Stockman,"High-power AlGaInN flip-chip light-emitting diodes," Appl. Phys. Lett. , Vol. 78, pp. 3379-3381, 2001.
[27] Y. Xi and E. F. Schubert,” Junction–temperature measurement in GaN ultraviolet light-emitting diodes using diode forward voltage method,” Appl. Phys. Lett. , Vol 85, pp. 2163-2165, 2004.
[28] Nakamura, T. Mukai, and M. Senoh, “Candela-class high-brightness InGaN/AlGaN double heterojunction blue light emitting diodes,” Appl. Phys. Lett., vol. 64, pp. 1687–1689, 1994.
[29] C. Huh, K. S. Lee, E. J. Kang, and S. J. Park, “Improved light-output and electrical performance of InGaN-based light-emitting diode by microroughening of the p-GaN surface,” J. Appl. Phys., vol. 93, pp. 9383–9286, 2003.
[30] R. Windisch, B. Dutta, M. Kuijk, A. Knobloch, S. Meinlschmidt, S. Schoberth, P. Kiesel, G. Borghs, G. H. Dohler, and P. Heremans, “40% efficient thin film surface textured light emitting diodes by optimization of natural lithography,” IEEE Trans. Electron Devices, vol. 47, pp. 1492–1498, July 2000.
[31] Hsu, Y. P., Chang, S. J., Su, Y. K., Sheu, J. K., Lee, C. T., Wen, T. C., Wu, L. W., Kuo, C. H., Chang, C. S., and Shei, S. C., "Lateral epitaxial patterned sapphire InGaN/GaN MQW LEDs," Journal of Crystal Growth, vol. 261, no. 4, pp. 466-470, 2004.
[32] Tsai, C. M., Sheu, J. K., Lai, W. C., Hsu, Y. P., Wang, P. T., Kuo, C. T., Kuo, C. W., Chang, S. J., and Su, Y. K., "Enhanced output power in GaN-based LEDs with naturally textured surface grown by MOCVD," IEEE Electron Device Letters, vol. 26, no. 7, pp. 464-466, 2005.
[33] Tsai, P.C., Chen, W.R., Su, Y.K., Huang, C.Y., “Enhanced light output of InGaN LEDs with a roughened p-GaN surface using different TMGa flow rates in p-AlGaN layer” APPLIED SURFACE SCIENCE, 256(22), 6694-6698, SEPTEMBER 2010.
[34] D. S. Kuo, S. J. Chang, C. F. Shen, T. C. Ko, T. K. Ko and S. J. Hon, "Nitride-based LEDs with oblique sidewalls and a light guiding structure", Semicond. Sci. Technol., Vol. 25, No. 5, Art. no. 055010, May 2010.
[35] D. S. Kuo, S. J. Chang, T. K. Ko, C. F. Shen, S. J. Hon and S. C. Hung, "Nitride-based LEDs with phosphoric acid etched undercut sidewalls", IEEE Photon. Technol. Lett., Vol. 21, No. 8, pp. 510-512, April 2009.
[36] Chang, C. S., Chang, S. J., Su, Y. K., Lee, C. T., Lin, Y. C., Lai, W. C., Shei, S. C., Ke, J. C., and Lo, H. M., "Nitride-based LEDs with textured side walls," IEEE Photonics Technology Letters, vol. 16, no. 3, pp. 750-752, 2004.
[37] H. Kudo, K. Murakami, R. Zheng, Y. Yamada, T. Taguchi, K. Tadatomo, H. Okagawa, Y. Ohuchi, T. Tsunekawa, Y. Imada, and M. Kato, “Intense ultraviolet electroluminescence properties of the high-power InGaN-based light-emitting diodes fabricated on patterned sapphire substrates,” Jpn. J. Appl. Phys., vol. 41, pp. 2484–2488, 2002.
[38] S. J. Chang, Y. C. Lin, Y. K. Su, C. S. Chang, T. C. Wen, S. C. Shei, J. C. Ke, C. W. Kuo, S. C. Chen and C. H. Liu, "Nitride-based LEDs fabricated on patterned sapphire substrates", Solid State Electron., Vol. 47, No. 9, pp. 1539-1542, September 2003.
[39] A. Bell, R. Liu, F. A. Ponce, H. Amano, I. Akasaki, and D. Cherns, “Light emission and microstructure of Mg-doped AlGaN grown on patterned sapphire,” Appl. Phys. Lett., vol. 82, pp. 349–351, 2003.
[40] Y. J. Lee, T. C. Hsu, H. C. Kuo, S. C.Wang, Y. L. Yang, S. N. Yen, Y. T. Chu, Y. J. Shen, M. H. Hsieh, M. J. Jou, and B. J. Lee, “Improvement in light-output efficiency of near-ultraviolet InGaN–GaN LEDs fabricated on stripe patterned sapphire substrates,” Mater. Sci. Eng. B, vol. 122, pp. 184–187, 2005.
[41] Hsu, Y. P., Chang, S. J., Su, Y. K., Sheu, J. K., Kuo, C. H., Chang, C. S., and Shei, S. C., "ICP etching of sapphire substrates," Optical Materials, vol. 27, no. 6, pp. 1171-1174, 2005.
[42] Chen, J. J., Su, Y. K., Lin, C .L., Chen, S. M., Li, W. L., Kao, C. C., “Enhanced output power of GaN-based LEDs with nano-patterned sapphire substrates”, IEEE PHOTONICS TECHNOLOGY LETTERS, 20(13-16), 1193-1195, JUL-AUG 2008.
[43] Su, Y. K., Chen, J. J., Lin, C. L., Chen, S. M., Li, W. L. , Kao, C. C., “GaN-Based Light-Emitting Diodes Grown on Photonic Crystal-Patterned Sapphire Substrates by Nanosphere Lithography”, JAPANESE JOURNAL OF APPLIED PHYSICS, 47(8), 6706-6708, AUG 2008.
[44] Su, Y. K., Chen, J. J., Lin, C. L., Chen, S. M., Li, W. L., Kao, C. C., “Pattern-size dependence of characteristics of nitride-based LEDs grown on patterned sapphire substrates”, JOURNAL OF CRYSTAL GROWTH, 311(10), P2973-2976, MAY 1, 2009.
[45] R. M. Lin, Y. C. Lu, S. F. Yu, Y. C. S. Wu, C. H. Chiang, W. C. Hsu and S. J. Chang, "Enhanced extraction and efficiency of blue light-emitting diodes prepared using two-step-etched patterned sapphire substrates", J. Electrochem. Soc., Vol. 156, No. 11, pp. H874-H876, November 2009.
[46] Y. P. Hsu, S. J. Chang, Y. K. Su, J. K. Sheu, C. H. Kuo, C. S. Chang and S. C. Shei, "ICP etching of sapphire substrates", Optical Mater., Vol. 27, No. 6, pp. 1171-1174, March 2005.
[47] J.M. Lee1, J.-H. Jang, T.K. Yoo"Scribing and cutting a blue LED wafer using aQ-switched Nd:YAG laser," Appl. Phys. A ,Vol. 70, 561–564 ,2000.
[48] E. Ohmura, F. Fukuyo, K. Fukumitsu, H. Morita,"Internal modified-layer formation mechanism into silicon with nanosecond laser," Journal of Achievements in Materials and Manufacturing Engineering,Volume 17 Issue 1-2,pp381-384, July-August 2006.
[49] S. Juodkazis, K. Nishimura, H. Misawa, T. Ebisui, R. Waki, S. Matsuo, and T. Okada,"Control over the Crystalline State of Sapphire," Adv. Mater., 18, pp1361–1364, 2006.
[50] S. J. Chang, W. C. Lai, Y. K. Su, J. F. Chen, C. H. Liu, and U. H. Liaw,“InGaN–GaN Multiquantum-Well Blue and Green Light-Emitting Diodes,”IEEE J. Sel. Topics Quantum Electron. ,vol. 8, no. 2,pp. 278-283,2002.
[51] S. J. Chang, C. H. Kuo, Y. K. Su, L.W. Wu, J. K. Sheu, T. C. Wen,W. C. Lai, J. F. Chen, and J. M. Tsai,“400-nm InGaN-GaN and InGaN-AlGaN multiquantum well light-emitting diodes," IEEE J. Sel. Topics Quantum Electron.,vol. 8, no.4, pp.744-748,2002.
[52] Y. K. Su, S. J. Chang, S. C. Wei, S. M. Chen, and W. L. Li,“ESD engineering of nitride-based LEDs,” IEEE Transactions on Device and Materials Reliability, vol. 5, no.2, pp.277-281,2005.
[53] S. J. Chang, W. C. Lai, Y. K. Su, J. F. Chen, C. H. Liu, and U. H. Liaw,“InGaN–GaN Multiquantum-Well Blue and Green Light-Emitting Diodes,”IEEE J. Sel. Topics Quantum Electron. ,vol. 8, no. 2,pp. 278-283,2002.
[54] S. J. Chang, C. H. Kuo, Y. K. Su, L.W. Wu, J. K. Sheu, T. C. Wen,W. C. Lai, J. F. Chen, and J. M. Tsai,“400-nm InGaN-GaN and InGaN-AlGaN multiquantum well light-emitting diodes," IEEE J. Sel. Topics Quantum Electron.,vol. 8, no.4, pp.744-748,2002.
[55] Y. K. Su, S. J. Chang, S. C. Wei, S. M. Chen, and W. L. Li,“ESD engineering of nitride-based LEDs,” IEEE Transactions on Device and Materials Reliability, vol. 5, no.2, pp.277-281,2005.
[56] J. K. Sheu, I-Hsiu Hung, W. C. Lai, S. C. Shei, and M. L. Lee," Enhancement in output power of blue gallium nitride-based light-emitting diodes with omnidirectional metal reflector under electrode pads", Appl. Phys. Lett. , 93, 2008, pp.103507.
[57] London Bullion Market Association.
[58] S. Nalamura, T. Mukai and M. Senoh, "High-Power GaN P-N Junction Blue-Light-Emitting," Jpn. J. Appl. Phys. ,vol. 30, no. 12A,pp. L1998-2001, 1991.
[59] F.A. Kish, D.A. DeFevere, D.A. Vanderwater,G.R. Trott, R.J. Weiss and J.S. Major, Jr."High luminous flux semiconductor wafer bonded AIGalnP/GaP large-area emitters," ELECTRONICS LETERS, Vol. 30, No. 21, p.p.1790-1792, 1994
[60]P. C. Tsai, Ricky W. Chuang, and Y. K. Su, "Lifetime Tests and Junction-Temperature Measurement of InGaN Light-Emitting Diodes Using Patterned Sapphire Substrates," JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 25, NO. 2, p.p. 591-596, 2007
[61]B. S. Tan, S. Yuan, X. J. Kang, "Performance enhancement of InGaN light-emitting diodes by laser lift-off and transfer from sapphire to copper substrate," Applied Physics Letters, v 84, n 15, p.p. 2757-2759, 2004.
[62]S.L. Chen, S.J. Wang, K.M. Uang, T.M. Chen, W.C. Lee, and B.W. Liou, "Fabrication of Dicing-Free Vertical-Structured High-Power GaN-Based Light-Emitting Diodes With Selective Nickel Electroplating and Patterned Laser Liftoff Techniques, "IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 19, NO. 6, p 351-353, 2007
[63]O. Kuckmann, "High power LED arrays special requirements on packaging technology," in Proc. of SPIE The Int. Soc. for Optical Engineering, vol. 6134, p.p.613404(1)-613404(8), 2006
[64]R. C. Jordan, J. Bauer, and H. Oppermann, “Optimized heat transfer and homogeneous color converting for Ultra High Brightness LED Package,” in Proc. of SPIE The Int. Soc. for Optical Engineering, Strasbourg, vol. 6198, pp. 61980B1-61980B12, 2006
[65]M. Arik, J. Petroski, S. Weaver, “Thermal challenges in the future generation solid state lighting applications: light emitting diodes,” in Conf. 8th Intersociety Conference on Thermal and Thermommechanical phenomena in Electronic Systems, San Diego,2002, pp. 113-120.