臺灣博碩士論文加值系統

近年來發光二極體(light emitting diodes ,LEDs)，由於其高亮度、高發光效率等優點，逐漸取代傳統燈源，並廣泛應用於生活。而目前常用來做 LED 的材料為氮化鎵(GaN)，氮化鎵須藉助基板成長磊晶，通常使用藍寶石基板，但兩者之間的晶格不匹配與熱膨脹系數差異，造成許多缺陷，使內部量子效率(IQE)下降。目前有許多改善GaN LED發光效率的方法被提出來，其中圖形化藍寶石基板(PSS)因為可大量生產且可同時提升內部量子效率(IQE)及光取出效率(LEE)，被大量使用。但其仍有可改善之處，根據文獻，不同形貌的PSS與AlN緩衝層的使用可改變磊晶機制並提升磊晶品質，因此本實驗設計以溼式蝕刻與鍍附緩衝層的方式，期望控制磊晶成長模式，並深入了解其磊晶機制。
實驗分兩部分流程進行，第一部分為直接將c-plane PSS溼式蝕刻，後分別直接高溫磊晶(PSSX)、先鍍附Low Temprature GaN緩衝層再高溫磊晶(PSSXL)、鍍附AlN緩衝層再高溫磊晶(PSSXA)。第二部分為先將c-plane PSS利用PECVD與黃光微影技術覆蓋氧化層在底部C面，再進行溼蝕刻，而後亦分別直接高溫磊晶(PSSO)、先鍍附LT GaN緩衝層再高溫磊晶(PSSOL)、鍍附AlN緩衝層再高溫磊晶(PSSOA)。
接著以掃描式電子顯微鏡(Scanning Electron Microscopy, SEM)與聚焦離子束系統(Focus Ion Bean, FIB)研究不同位置氮化鎵磊晶成長速率。發現使用溼式蝕刻與緩衝層，的確可以改變磊晶成長的位置。濺鍍AlN緩衝層後，磊晶傾向成長在底部C面。因此藉著溼式蝕刻與緩衝層的使用，本實驗成功的製作出GaN只從底部C面區域成長磊晶的PSS。

Recently, Light-emitting diodes (LEDs) have been replaced traditional light sources and widely been used in life due to their advantage of high brightness and high efficiency. The material of LEDs is GaN, the epitaxy of GaN relies on substrates. The common substrate is sapphire. There are still many problems between sapphire and GaN such as lattice mismatch and thermal expansion coefficient difference, which will make defects and degrade internal quantum efficiency (IQE). Many methods are proposed to improve the efficiency of GaN LED. Patterned sapphire substrates (PSS) are preferred because of advantages such as improving IQE, LEE and high production rate. However, there are still some problem when using PSS. According to the previous studies, the morphology of PSS and the sputtering AlN buffer layer both affect the growth mechanism of GaN, then improve the crystal quality. Therefore, the experiment included wet-etching and buffer layer methods. I expect to control the growth mode of GaN and figure out the growth mechanism of GaN in depth.
The experiment is composed of two parts. In the first part, the c-plane PSSs are wet-etched directly and then grow GaN without buffer layer(PSSX), with LT GaN buffer layer(PSSXL) and with AlN buffer layer(PSSXA) respectively. In the second part, the bottom of c-plane PSSs are cover with oxide mask before wet-etched and then also grow GaN without buffer layer(PSSO), with LT GaN buffer layer(PSSOL) and with AlN buffer layer(PSSOA) respectively.
The growth rates on diffrient planes are investigated with Scanning Electron Microscopy(SEM) and Focus Ion Bean(FIB).It confirmed that through wet-etching technique that modified the PSS and growing buffer layer, the initial growth position of GaN was changed. With sputtering AlN buffer layer, GaN grains mainly grow on the c-plane sapphire region rather than on the sidewall region of PSS. Consequently, the experiment successfully maked out the PSS that GaN only grow on the the c-plane sapphire region with wet-etching and buffer layer.

中文摘要...................................I Abstract.................................III
致謝.......................................V
目錄......................................VI
圖目錄..................................VIII
表目錄..................................XIII
一、序論 ..................................1
1.1發光二極體發展與應用 ..................1
1.2發光二極體理論 ..................1
1.2.1發光原理 ..........................1
1.2.2 LED發光機制 ..................3
1.2.3 LED轉換效率 ..................4
1.2.4 藍寶石基板 ..................5
1.2.5 藍寶石與氮化鎵晶體結構以及特性簡介 ..8
1.3 圖形化藍寶石基板介紹及其優點 ..........11
1.3.1 乾蝕刻簡介 ..................13
1.3.2 濕蝕刻簡介 ..................13
二、溼蝕刻藍寶石圖形化基板與緩衝層對氮化鎵磊晶影響之研究...16
2.1 動機 ..................16
2.2實驗流程 ..................19
2.3結果與討論 ..................22
2.3.1 蝕刻程度與特殊面 ..................22
2.3.2溼式蝕刻圖形化藍寶石基板 ..........24
2.3.3 LT GaN buffer layer在溼式蝕刻圖形化藍寶石基板 ....32
2.3.4 sputtering AlN buffer layer在溼式蝕刻圖形化藍寶石基板 .....38
2.3.5 蝕刻與緩衝層對磊晶情況 ..........45
三、總結 ..................46
四、未來實驗規劃 .................. 48
五、參考文獻 ..................49

1. Round,H.J., Electrical world Vol. 49. 1907: [New York McGraw-Hill Pub. Co., etc.].
2. 劉如熹,王健源,白光發光二極體製作技術-21世紀人類新曙光,全華科技圖書,初版(民90),pp.1-13,1-14
3. 史國光,半導體發光二極體及固態照明,全華出版,二版(民99),pp.1-20
4. 陳俞中, “濕蝕刻藍寶石圖形化基板形貌演化對氮化鎵磊晶的影響,國立交通大學,博士論文,民國103年3月,pp.2,3,4,6,8,11
5. 郭浩中,賴芳儀,郭守義,LED原理與應用,五南出版,二版3-8 (2012),pp.80
6. N.F. Gardner, H.C. Chui, E.I. Chen, M.R. Krames, J.-W. Huang, F.A. Kish, et al., 1.4× efficiency improvement in transparent-substrate(Al xGa 1−x ) 0.5 In 0.5 Plight-emitting diodes with thin (≤2000 Å) active regions, Appl. Phys. Lett. 74 (1999),pp.2230.
7. Jr. W. Shockley and W. T. Read, A model for the field and temperature dependence of Shockley-Read-Hall lifetime in silicon,Phys. Rev. 87, No.835(1952),pp.1585.
8. 林家振, “利用虛線圖形化藍寶石基板於{123 ̅5}成長氮化鎵＂,國立交通大學,碩士論文,民國104年8月,pp.4
9. E.R. Dobrovinskaëiìa, L.A. Lytvynov, V.V. Pishchik, Sapphire: material, manufacturing, applications, Springer (2009),pp.58.
10. W.E. Lee, K.P.D. Lagerlof, Structural and electron-diffraction data for sapphire (α-Al2O3), J Electron Micr Tech. 2 (1985),pp.247.
11. I. Vurgaftman, J.R. Meyer, Band parameters for nitrogen-containing semiconductors, J. Appl. Phys. 94 (2003),pp.3675. 

12. T. Hanada, Basicp of ZnO, GaN, and related materials, Springer (2009),pp.3. 

13. H. Morkoç, S. Strite, G.B. Gao, M.E. Lin, B. Sverdlov, M. Burns, Large- band-gap SiC, III-V nitride, and II-VI ZnSe-based semiconductor device technologies, J. Appl. Phys. 76 (1994) ,pp.1363. 

14. J.N. Kuznia, M.A. Khan, D.T. Olson, R. Kaplan, J. Freitas, Influence of 
buffer layers on the deposition of high quality single crystal GaN over sapphire substrates, J. Appl. Phys. 73 (1993) ,pp.4700. 

15. S. Nakamura, GaN growth using GaN buffer layer, Jpn. J. Appl. Phys. 30 (1991),pp.1705. 

16. K. Uchida, K. Nishida, M. Kondo, H. Munekata, Epitaxial growth of GaN layers with double-buffer layers, J.Cryst.Growth. 189 (1998),pp. 270. 

17. M.S. Yi, H.H. Lee, D.J. Kim, S.J. Park, D.Y. Noh, C.C. Kim, et al., Effects of growth temperature on GaN nucleation layers, Appl. Phys. Lett. 75 (1999) ,pp.2187. 

18. H. Amano, N. Sawaki, I. Akasaki, Y. Toyoda, Metalorganic vapor phaseepitaxial growth of a high quality GaN film using an AlN buffer layer, Appl. Phys. Lett.48 (1986) ,pp.353.

19. D.J. Park, J.Y. Lee, H.-K. Cho, C.-H. Hong, H.S. Cheong, Dislocation 
reduction in GaN epilayers by maskless pendeo-epitaxy process,J.Korean.Phys.Soc. 45 (2004) ,pp.1253. 

20. A.M. Roskowski, E.A. Preble, S. Einfeldt, P.M. Miraglia, J. Schuck, R.Grober,et al., Reduction in dislocation density and strain in GaN thin films grown via maskless pendo-epitaxy,OPTO-ELECTRON.REV. 10 (2002) ,pp.261. 

21. T.S. Zheleva, W.M. Ashmawi,K.A. Jones, Pendeo-epitaxy versus lateral epitaxial overgrowth of GaN: A comparative study via finite element analysis, Phys. Stat. Sol. (a). 176 (1999) ,pp.545. 

22. T.S. Zheleva, S.A. Smith, D.B. Thomson, K.J. Linthicum, P. Rajagopal, R.F. Davis, Pendeo-epitaxy: A new approach for lateral growth of gallium nitride films, J. Electron. Mater. 28 (1999),pp. 5. 

23. P. Fini, L. Zhao, B. Moran, M. Hansen, H. Marchand, J.P. Ibbetson, et al., High-quality coalescence of laterally overgrown GaN stripes on GaN/sapphire seed layers, Appl. Phys. Lett. 75 (1999) ,pp.1706. 

24. H. Miyake, A. Motogaito, K. Hiramatsu, Effects of reactor pressure on epitaxial lateral overgrowth of GaN via low-pressure metalorganic vapor phase epitaxy, Jpn. J. Appl. Phys. 38 (1999),pp. 1000. 

25. T. Nishinaga, T. Nakano, S. Zhang, Epitaxial lateral overgrowth of GaAs by LPE, Jpn. J. Appl. Phys. 27 (1988),pp. 964. 

26. S. S. Schad et al.The study and fabrication of vertical structure GaN-based light-emitting diodes with a reflection mirror layer“Phys. Stat. Sol.(a)” 188(2001),pp.127.
27. T. Fujii,Y. Gao, R. Sharma, E. L. Hu, S. P. DenBaars, and S. Nakamuraa,Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening,Appl. Phys. Lett. 84 (2004), pp.855.
28. R. H. Horng et al.Characterization of Large-Area AlGaInP/Mirror/Si Light-Emitting Diodes Fabricated by Wafer Bonding,“Jpn, J. Appl. Phys.43, No.5A(2004),pp.2510.
29. J. J. Wierer et al. High-power AlGaInN flip-chip light-emitting diodes“Appl. Phys. Lett.78,No.22 (2001),pp.3379.
30. K. Harafuji, T. Tsuchiya, K. Kawamura, Molecular dynamics simulation for evaluating melting point of wurtzite-type GaN crystal, J. Appl. Phys. 96 (2004),pp. 2501.
31. 陳建誌, “圖案化藍寶石基板表面形貌對氮化鎵系發光二極體影響＂,國立交通大學,博士論文,民國103年8月,pp.22
32. N. S. Yu, L. W. Guo, H. Chen, Z. G. Xing, B. H. Ge, J. Wang, X. L. Zhu, M. Z. Peng, J. F. Yan, H. Q. Jia, and J. M. Zhou, J. Alloy. Compd., 428, 312(2007)
33. T. S. Oh, H. Jeong, Y. S. Lee, T. H. Seo, A. H. Kim, K. J. Lee, M. S. Jeong, and E. K. Suh, Thin Solid Films., 519, 2398(2011)
34. M. Liang, G. Wang, H. Li, Z. Li, R. Yao, B. Wang, P. Li, J. Li, X. Yi, J. Wang, and J. Li, J. Semicond., 33, 113002(2011)
35. D. S. Wuu, W. K. Wang, K. S. Wen, S. C. Huang, S. H. Lin, R. H. Horng, Y. S. Yu, and M. H. Pan, J. Electrochem. Soc., 153, G765(2006)
36. Y. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, J. Disp. Technol., 3, 118(2007)
37. C. Xu, T. Yu, J. Yan, Z. Yang, X. Li, Y. Tao, X. Fu, Z. Chen, and G. Zhang., Phys. Stat. Sol. (c), 9, 757(2011)
38. N. Han, H. G. Kim, H. Y. Kim, H. K. Kim. J. H. kang, J. H. Ryu, Y. S. Lee, E. K. Suh, and C. H. Hong, Jpn. J. Appl. Phys., 48, 110201(2009)
39. M. Wu, Y. P. Zeng, J. X. Wang, and Q. Hu, Chin. Phys. Lett., 28, 068502(2011)
40. 莊達人, VLSI 製造技術, 高立出版, 六版 (2007),pp. 356. 

41. 蕭宏, 半導體製程技術討論, 培生出版, 三版 (2007) ,pp.315. 

42. F. Dwikusuma, D. Saulys, T.F. Kuech, Study on sapphire surface 
preparation for III-nitride heteroepitaxial growth by chemical treatments, 
J. Electrochem. Soc.149 (2002) ,pp.603. 

43. Y.J. Chen, C.H. Kuo, C.J. Tun, S.C. Hsu, Y.J. Cheng, C.Y. Liu, Fabrication of high-power InGaN-based light-emitting diode chips on pyramidally patterned sapphire substrate, Jpn. J. Appl. Phys. 49 (2010) ,pp.020201.
44. D.S. Wuu, W.K. Wang, K.S. Wen, S.C. Huang, S.H. Lin, R.H. Horng, et al., Fabrication of pyramidal patterned sapphire substrates for high-efficiency InGaN-based light emitting diodes, J. Electrochem. Soc. 153 (2006) ,pp.765.

45. S.J. Kim, Vertical electrode GaN-based light-emitting diode fabricated by selective wet etching technique, Jpn. J. Appl. Phys. 44 (2005) ,pp.2921. 

46. Hui-Youn Shin, S. K. Kwon, Y.I. Chang, M.J. Cho, K.H. Park, Reducing dislocation density in GaN films using a cone-shaped patterned sapphire substrate, J.Cryst.Growth. 311 (2009), pp.4167–4170
47. Hung-Cheng Lin, Hsueh-Hsing Liu, Geng-Yen Lee, Jen-Inn Chyi, et al., Effects of Lens Shape on GaN Grown on Microlens Patterned Sapphire Substrates by Metallorganic Chemical Vapor Deposition, J. Electrochem. Soc. 157 (3)(2010), pp. 304-307
48. H. Hu, S. Zhou, X. Liu 1 , Y. Gao, C. Gui, and S. Liu, Sci. Rep., 7, 44627(2017).
49. L. C. Chang, Y. A. Chen, and C. H. Kuo, IEEE T. Electron Dev., 61, 2443(2014).
50. J.D. Plummer, M. Deal and P. B. Griffin, Silicon VLSI Technology: Fundamentals, Practice, and Modeling, 1st ed., Prentice Hall, New Jersey, 514(2000).
51. D.D. Ebbing, General Chemistry, 5th ed., Princeton, New Jersey,545(1996).
52. 吳珮瑜, “氮化鎵薄膜磊晶在圖案化基板上” 國立交通大學，博士論文，民國106年10月，pp.69,70