隨著發光二極體在生活中的應用越來越為廣泛，對於其發光效率及光源的配置就格外顯的重要。本論文最主要的目的是藉由使用圖樣化藍寶石基板 (Pattern Sapphire Substrate, PSS) 及運用壓印技術(Imprint Technology) 製作表面微結構的發光二極體，來達到對發光效率的提升與遠場光型的調制效果。
我們使用四種不同結構的模具將微結構壓印於有、無圖樣化藍寶石基板之發光二極體表面上，相互作為比較，並分別進行電特性、光特性及遠場光型的量測，觀察其對發光效率及遠場光型的改變。
由實驗結果顯示，有壓印微結構於發光二極體表面的電特性與無壓印微結構相較，幾乎維持一致，證實運用壓印技術配合相關製程，並不會影響電特性。在出光表現上，在20mA電流操作下，有、無圖樣化藍寶石基板之發光二極體相比較，前者可提升光強度約1.5倍；製作壓印微結構於具圖樣化藍寶石基板之發光二極體，依據所製作的圓洞 (Hole) 、金字塔 (Pyramid) 、圓錐 (Cone) 以及光柵 (Grating)四種圖形結構，與沒有壓印微結構相比較，光強度分別提升27 %、12 %、13 %及26 %。光型調制方面，由壓印結構在無圖樣化基板之發光二極體表面的遠場光型圖，可以發現依不同的幾何結構，會得到相對應的光型改變；從壓印結構於有圖樣化基板之發光二極體表面的遠場光型圖來分析，所有具有壓印結構與沒有壓印結構的光型幾乎呈現一致，可知光源調制效果會由圖樣化基板所改變的光型所主導，顯示出微結構對有圖樣化基板的發光二極體來說，對整體輸出光型的影響並不顯著。

With the wide application of LED, the LED light extraction efficiency and the arrangement of the light source are important. In this thesis, the surface microstructure by Pattern Sapphire Substrate (PSS) and Imprint Technology are employed to enhance the light extraction efficiency and modulate the far-field light pattern of LEDs.
There are four different configurations for imprinting the microstructure on the surfaces of the substrate with and without PSS. The electrical properties, light characteristics, and the measurement of far-field light patterns of these two substrates are used to observe the light efficiency and the variations of far-field light pattern.
From the experimental results, the electrical properties of the imprinting microstructure with and without PSS are consistent, which confirms the electrical properties are not affected by LED process and the imprinting method. In the light extraction efficiency, it can enhance the light output power of PSS LEDs to 1.5 times under the current of 20mA.
The LEDs with PSS are imprinted with four structures which are Hole, Pyramid, Cone, and Grating. Comparing with the conventional LED, it shows the light extraction enhancements of each structure are 27%, 12%, 13%, and 26% respectively. In the modulation of light pattern, the imprinting structure with different structures on the LED without PSS shows the correspondent far-field light patterns vary with the geometric structure types. Both of the light pattern which are with and without imprinting microstructure are consist by the analysis of the far-field light pattern of imprinted microstructure the PSS LED. It can be concluded that the effects of light pattern modulation are dominated by the microstructures on substrate of LEDs but slightly affected by the imprinted microstructure on the LED.

參 考 文 獻
[1] S. Yoshida, S. Misawa, and S. Gonda, “Improvements on the electrical and luminescent properties of reactive molecular beam epitaxially grown GaN films by using AlN-coated sapphire substrates”, Appl. Phys. Lett., vol.42, pp.427-429, 1983.
[2] I. Akasaki, H.Amano, Y.Koide, K. Hiramatsu, and N.Sawaki, “Effects of ALN buffer layer on crystallographic structure and on electrical and optical-properties of GaN and Ga1-xAlxN films grown on sapphire substrate by MOVPE,” Journal of Crystal Growth, Vol. 98, pp.209,1989.
[3] S. Nakamura, “GaN growth using GaN buffer layer,” Japanese Journal of Applied Physics Part 2-Letters, Vol.30, pp. L1705,1991.
[4] I. Akasaki, H. Amano, Y. Koide, K. Hiramatsu, and N. Sawaki, J. Crystal Growth 98, 209 (1989).
[5] S. Nakamura, M. Senoh, and T. Mukai,” Highly p-typed Mg-doped GaN films grown with GaN buffer layer,” Japanese Journal of Applied Physics, Vol. 30, pp. L1708, 1991.
[6] http://www.nichia.com/de/about_nichia/2006/2006_122001.html.
[7] ITRS, 取自http://public.itrs.net/
[8] S.Y. Chou, P.R. Krauss, W. Zhang, L. G. Guo, and L. Zhuang, “Sub-10 nm imprint lithography and applications,” Journal of Vaccuum Science & Technology B, Vol. 15, pp. 2897, 1997.
[9] S. Y. Chou, P. R. Krauss, “Imprint lithography with sub-10 nm feature size and high throughput,” Microelectronic Engineering, Vol. 35, pp.237, 1997.
[10] S. Y. Chou, P. R. Krauss, and P. J. Renstrom,“Imprint lithography with 25-nanometer resolution,” Science, Vol. 272, pp. 85, 1996.
[11] S.Y. Chou, P.R. Krauss, and P.J. Renstrom,” Imprint of sub-25 nm vias and trenches in polymers,“ Applied physics letters, Vol. 67, pp. 3114, 1995.
[12] 國立中央大學光電科學與工程學系，「光電科技概論」，五南出版社，2008
[13] E. Fred Schubert，「Light – Emitting Diodes」，CAMBRIDGE，2006
[14] 陳隆建，「半導體發光二極體及固體照明」，全華科技圖書股份有限公司印行，2007
[15] 史光國，「半導體發光二極體及固體照明」，全華科技圖書股份有限公司印行，2006
[16] M. R. Krames, G. E. Höfler, E. I. Chen, I. H. Tan, P. Grillot, N. F. Gardner, H. C. Chui, J. W. Huang, S. A. Stockman, F. A. Kish, and M. G. Craford, “High powertruncated inverted pyramid AlxGa12x.0.5In0.5P/GaP light-emitting diodes exhibiting >50% external quantum efficiency,” Applied physics letters, Vol. 75, pp. 2365, 1999.
[17] J. Y. Kim, M. K. Kwon, J. P. Kim, and S. J. Park, “ Enhanced Light Extraction From Triangular GaN-Based Light-Emitting Diodes,” IEEE Phot. Tech. Lett., Vol. 19, NO.23, 2007.
[18] Chul Huh, Kug-Seung Lee, Eun-Jeong Kang, and Seong-Ju Park, “Improved light-output and electrical performance of InGaN-based light-emitting diode by microroughening of the p-GaN surface,” Journal of Applied Physics, Vol. 93, No. 11, pp.9383, 2003.
[19] H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, and Y. Park, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers, ” Applied physics letters, Vol. 90, pp. 161110, 2007.
[20] H. W. Huang, H. C. Kuo, J. T. Chu, C. F. Lai, C. C. Kao, T. C. Lu, S. C. Wang, R. J. Tsai, C. C. Yu, and C. F. Lin,” Nitride-based LEDs with nano-scale textured sidewalls using natural lithography,” Institute of physics publishing nanotechnology, vol. 17, 2006.
[21] T. S. Kim, S. M. Kim, Y. H. Jang, and G. Y. Jung, ”Increase of light extraction from GaN based light emitting diodes incorporating patterned structure by colloidal lithography,” Applied physics letters, Vol. 91, pp. 171114, 2007.
[22] Y. J. Lee, J.M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Phot. Tech. Lett., Vol. 18, NO.10, 2006.
[23] T. X. Lee, K. F. Gao, W. T. Chien, and C. C. Sun, “Light extraction analysis of GaN-based light-emitting diodes with surface texture and/or patterned substrate,“Optical Society of America, Vol. 15, No. 11, 2007.
[24] 張育嘉，「圖形化藍寶石基板應用於氮化加發光二極體之研究」，國立中央大學碩士論文，民國九十七年。
[25] K. Bao, X. N. Kang, B. Zhang, T. Dai, C. Xiong, H. Ji, G. Y. Zhang, and Y. Chen, “Improvement of Light Extraction From Patterned Polymer Encapsulated GaN-Based Flip-Chip Light-Emitting Diodes by Imprinting,” IEEE , Vol. 19, pp. 20, 2007.