本論文探究以有機金屬化學氣相沉積法(MOCVD)成長之氮化銦鎵(包覆氮化銦鎵類量子點)/氮化鎵多重量子井(InGaN/GaN multiple quantum wells)之微結構及光學性質。氮化銦鎵量子井中，由於相分離緣故，導致其內包覆銦富集區域，亦即氮化銦鎵類量子點。吾人利用高解析穿透式電子顯微鏡(HRTEM)探測材料之微結構；利用高解析X光繞射(HRXRD)之ω-2θ及ω-scan分析法解析薄膜之結晶性及界面性質；利用螢光激發光譜(PL)、微觀光激發光譜(micro-PL)、螢光吸收光譜(PLE)及時間解析光激發光譜(time-resolved PL)進行薄膜光學性質之整合性研究。
本論文依研究主題可區分為五大部分。首先，吾人證明利用氮化銦鎵類量子點(quantum dots)結構可使氮化銦鎵/氮化鎵多重量子井之發光波長於可見光區域由藍光調變至黃光。此外，一般在高銦含量氮化銦鎵/氮化鎵系統中常觀察到之結晶性衰退現象，利用此成長方法也可有效避免。另一方面，吾人也發現類量子點結構就如同真實量子點般，可抑制穿透差排之傳播。
第二部份，吾人則以實驗及理論方法來量測並計算氮化銦鎵類量子點中銦元素之含量。藉由綜合性的理論計算，包含自發極化場(polarization field)、壓電場(piezoelectric field)以及尺寸因素(size effect)等效應，得知2奈米(綠光)及3 奈米(藍光)銦富集團簇中銦元素含量分別為59%及31%。吾人同時發現，在綠光氮化銦鎵/氮化鎵多重量子井中主導的發光機制為極化場，而在藍光氮化銦鎵/氮化鎵中則是尺寸效應及極化場同等重要。
第三部份則探討量子阻障層(barrier)成長溫度對藍光氮化銦鎵/氮化鎵系統之微結構及發光性質之影響。結果顯示，若將阻障層成長溫度由700 ℃ 提高到800 ℃，氮化銦鎵發光層之微結構會由銦含量均勻分佈狀態轉變為包覆直徑2±0.2 奈米之氮化銦鎵類量子點。在後者中觀察到強壓電場之存在、S型載子傳輸及高內部量子效率(71.3%)，推論為量子點的形成所導致。進而，吾人也證明量子阻障層以較高溫度成長之試片其發光二極體(light emitting diodes, LED) chip在20毫安培下之操作電壓及光輸出瓦數較低溫度成長之試片低了0.3伏特及高了11%。
第四部分，吾人研究綠光氮化銦鎵/氮化鎵多重量子井中之載子於氮化銦鎵類量子點(quasi-dots)及氮化銦鎵母材(matrix)間之傳輸行為。由氮化銦鎵母材之發光光譜可觀察到S型變化及341毫電子伏特的史塔克位移(Stoke’s shift)，推論除了銦富集區域外，母材中也有些微的成分波動。此外，吾人也發現母材中之載子其生命期較短且呈現兩階段式衰減，因此，進而推論量子井中之載子會由低銦含量母材飄移(drift)到高銦含量量子點，進而增強量子點(綠光)之發光效率。
最後一部份，吾人研究材料極性對氮化銦鎵/氮化鎵多重量子井發光性質之影響。根據微結構圖像及發光光譜，吾人發現無論在鎵極性(Ga-polarity)或氮極性(N-polarity)試片中，都可觀察到相分離現象存在。而鎵極性之氮化銦鎵量子點與氮極性試片相比較，擁有較強載子侷限效應、對溫度之低靈敏度及較不會受結構缺陷所影響等優點。此外，氮化銦鎵母材與類量子點間之載子傳輸行為只於鎵極性試片中被觀察到。

This dissertation explores the microstructure and optical properties of InGaN/GaN multiple quantum wells (MQWs) comprised of InGaN quasi-dots, which were grown by metalorganic chemical vapor deposition (MOCVD). Microstructure of the samples was characterized by high resolution transmission electron microscopy (HRTEM). The crystallinity and interface quality of the samples were determined by ω-2θ and ω-scan analysis with high resolution x-ray diffraction (HRXRD). The optical properties of the samples were investigated by combining low-temperature photoluminescence (PL), micro-PL, PL excitation (PLE) and time-resolved PL measurements.
The main focus of this dissertation can be divided into five parts. First, we demonstrated that the emission wavelength of InGaN/GaN MQWs can be tuned from the blue to yellow in the visible spectral region by using InGaN dots. The common degradation phenomenon on crystallinity often observed in InGaN/GaN system with higher indium concentration was found being avoided by this kind of growth. In addition, we also found that the propagation of threading dislocations would be efficiently stopped by the quasi-dots, which behave as real quantum dots.
Then, the indium content within the InGaN quasi-dots was estimated experimentally and theoretically. Comprehensive calculations including polarization, piezoelectric field and size effect help derive an indium composition of 59 % and 31 % for the In-rich clusters of 2 nm and 3 nm. We further demonstrated that the dominant emitting mechanism for green InGaN/GaN MQWs is polarization field, however, for blue InGaN/GaN, both size effect and polarization effect are equally important.
In the third part, the effect of barrier growth temperature on blue InGaN/GaN MQWs was studied. It was found that the InGaN active layers composed of InGaN quasi-dots of 2±0.2 nm in diameter, changing from homogeneous nature, could be obtained by elevating the barrier growth temperature from 700 to 800 ºC. The strong piezoelectric field, “S-shape-like” carrier transition and high internal quantum efficiency of 71.3% were observed in the sample with a higher barrier growth temperature, closely related to the dots formation. Furthermore, the forward voltage and the light output power at 20 mA of light emitting diodes from the sample with dots were 0.3 V lower and 11% higher than that from the homogeneous multiple quantum wells.
In the fourth part, the carrier transfer between InGaN dots and InGaN matrix was investigated in the green InGaN/GaN MQWs. Except for the strong indium aggregation, slight composition fluctuations were also observed in the InGaN matrix, which were speculated from an “S-shaped” transition and a Stokes shift of 341meV. In addition, a shorter lifetime and ‘two-component’ PL decay were also found for the InGaN matrix. Thus, the carrier transport process within quantum wells is suggested to drift from the low-In-content matrix to the high-In-content dots, resulting in the enhanced luminescence efficiency of the green light emission.
The influence of material polarity on the emission properties of InGaN/GaN MQWs was discussed in the final part. A clear phase separation was observed both in Ga- and N-polarity samples, corresponding to two InGaN-related emissions ( InGaN dots and an InGaN matrix) seen in photoluminescence (PL) spectra. We demonstrated that the dot-related emission in the Ga-polarity MQWs shows stronger carrier localization, little influence by defects and higher temperature insensitivity as compared to N-polarity MQWs. In addition, the efficient carrier transport from the low-indium InGaN matrix to high-indium In-rich dots was observed in the Ga-polarity structure, but not in the N-polarity one.

1.S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, Jpn. J. Appl. Phys. 34, L797 (1995).
2.S. Nakamura, M. Senoh, S. Nagahama, and N. Iwasa, Jpn. J. Appl. Phys. 35, L74 (1996).
3.史光國, “GaN藍色發光及雷射二極體之發展現況”, 工業材料, 126, 154頁 (1997).
4.廖偉材, “氮化鋁鎵/氮化鎵超晶格原子層磊晶之研究”, 逢甲大學材料科學研究所, 碩士論文 (2002).
5.S. Yoshida, S. Misawa, and S. Gonda, Appl. Phys. Lett. 42, 427 (1983).
6.H. Amano, N. Sawaki, I. Akasaki, and Y. Toyota, Appl. Phys. Lett. 48,353 (1986).
7.H. Amano, M. Kito, K. Hiranatsu, and I. Akasaki, Jpn. J. Appl. Phys. Part2 28, L212 (1989).
8.S. Nakamura, Jpn. J. Appl. Phys. 30, L1705 (1991).
9.I. Akosaki, S. Sota, H. Sakai, T. Tanaka, M. Koike, and H. Amano, Electron. Lett. 32, 1105 (1996).
10.M. Mack, A. Abare, M. Aizcorbe, P. Kozodoy, S. Keller, U. Mishra, L. Coldren, and S. DenBaars, MRS Internet J. Nitride Semicond. Res. 2, 41 (1997).
11.S. Chichibu, T. Azuhata, T. Sota, and S. Nakamura, Appl. Phys. Lett. 69, 4188 (1996).
12.K. Osamura, K. Nakajima, and Y. Murakami, Solid State Commum. 11, 617 (1972).
13.K. Osamura, S. Naka, and Y. Murakami, J. Appl. Phys. 46, 3432 (1975).
14.C. Y. Hwang, “Growth and Characterization of Gallium Nitride on (0001) sapphire by Plasma Enhanced Atomic Layer Epitaxy and by Low Pressure Metaloganic Chemical Vapor Deposition”, Ph.D. dissertation, Rutgers University, Piscataway, NJ, (1995).
15.B. Gil, “Group III Nitride Semiconductor Compounds”, Oxford, New York (1998).
16.S. C. Jain, M. Willander, J. Narayan, and R. Van Overstraeten, J. Appl. Phys. 87, 965 (2000).
17.J. L. Sanchez-Rojas, J. A. Garrido, and E. Muooz, Phys. Rev. B 61, 2773 (2000).
18.F. Bernardini, V. Fiorentini, and D. Vanderbilt, Phys. Rev. B 56, 10024 (1997).
19.H. Morkoc, “Nitride Semiconductors and Devices”, Springer-Verlag, Berlin (1999).
20.I. Ho and G. B. Stringfellow, Appl. Phys. Lett. 69, 2701 (1996).
21.S. Y. Karpov, MRS Internet J. Nitride Semicond. Res. 3, 16 (1998 ).
22.M. K. Behbehani, E. L. Piner, S. X. Liu, N. A. EI-Masry, and S. M. Bedair, Appl. Phys. Lett. 75, 2202 (1999).
23.Y. T. Moon, D. J. Kim, J. S. Park, J. T. Oh, J. M. Lee, Y. W. Ok, H. Kim, and S. J. Park, Appl. Phys. Lett. 79, 599 (2001).
24.H. K. Cho, J. Y. Lee, N. Sharma, C. J. Humphreys, G. M. Yang, C. S. Kim, J. H. Song, and P. W. Yu, Appl. Phys. Lett. 79, 2594 (2001).
25.M. Takeguchi, M. R. McCartney, and D. J. Smith, Appl. Phys. Lett. 84, 2103 (2004).
26.M. Rao, D. Kim, and S. Mahajan, Appl. Phys. Lett. 85, 1961 (2004).
27.I. K. Park, M. K. Kwon, S. H. Baek, Y. W. Ok, T. Y. Seong, S. J. Park, Y. S. Moon, and D. J. Kim, Appl. Phys. Lett. 87, 061906 (2005).
28.T. M. Smeeton, M. J. Kappers, J. S. Barnard, M. E. Vickers, and C. J. Humphreys, Appl. Phys. Lett. 83, 5419 (2003).
29.J. P. O’Neill, I. M. Ross, A. G. Cullis, T. Wang, and P. J. Parbrook, Appl. Phys. Lett. 83, 1965 (2003).
30.M. G. Cheong, C. Liu, H. W. Choi, B. K. Lee, E. K. Suh, and H. J. Lee, J. Appl. Phys. 93, 4691 (2003).
31.S. Lazic, M. Moreno, J. M. Calleja, A. Trampert, K. H. Ploog, F. B. Naranjo, S. Fernandez, and E. Calleja, Appl. Phys. Lett. 86, 061905 (2005).
32.J. Wagner, A. Ramakrishnan, H. Obloh, and M. Maier, Appl. Phys. Lett. 74, 3863 (1999).
33.M. Stevens, A. Bell, M. R. McCartney, F. A. Ponce, H. Marui, and S. Tanaka, Appl. Phys. Lett. 85, 4651 (2004).
34.Y. H. Cho, G. H. Gainer, A. J. Fischer, J. J. Song, S. Keller, U. K. Mishra, and S. P. DenBaars, Appl. Phys. Lett. 73, 1370 (1998).
35.P. G.. Eliseev, P. Perlin, J. Lee, and M. Osinski, Appl. Phys. Lett. 71, 569 (1997).
36.K. L. Teo, J. S. Coton, P. Y. Yu, E. R. Weber, M. F. Li, W. Liu, K. Uchida, H. Tokunaga, N. Akutsu, and K. Matsumoto, Appl. Phys. Lett. 73, 1697 (1998).
37.S. C. Chung, “Physics of Optoelectronic Devices” Chap. 3, Wiley, New York (1995).
38.張立德, 牟季美, “奈米材料與奈米結構”, 滄海書局 (2002).
39.D. J. Eaglesham and M. Cerullo, Phys. Rev. Lett. 64, 1943 (1990).
40.I. N. Stranski and L. Krastanow, Sitzungsberichte d. Akad. d. Wissenschaften in Wien, Abt. Iib, Band 146, 797 (1937).
41.Y. W. Mo, D. E. Savage, B. S. Swartzentruber, and M. G. Lagally, Phys. Rev. Lett. 65, 1020 (1990).
42.A. Madhukar, Q. Xie, P. Chen, and A. Konkar, Appl. Phys. Lett. 64, 2727 (1994).
43.E. Kurtz, M. Schmidt, M. Baldauf, S. Wachter, M. Grun, D. Litvinov, S. K. Hong, J. X. Shen, T. Yao, D. Gerthsen, H. Kalt, and C. Klingshirn, J. Cryst. Growth 214/215, 712 (2000).
44.許樹恩, 吳泰伯, “X光繞射原理與材料結構分析”, 國科會精儀中心發行, 科儀叢書6.
45.B. D. Cullity, “Elements of X-ray Diffraction”, Addison-Wesley, Reading, MA (1967).
46.P. F. Fewster, Phillips J. Res. 41, 268 (1986).
47.L. T. Romano, B. S. Krusor, M. D. McCluskey, D. P. Bour, and K. Nanka, Appl. Phys. Lett. 73, 1757 (1998).
48.徐煥棠, “摻雜稀土元素於磷砷化銦鎵之特性研究”, 私立中原大學, 碩士論文 (2001).
49.D. B. Williams and C. B. Carter, “Transmisison Electron Microscopy”, Plenum, New York (1996).
50.R. E. Lee, “Scanning Electron Microscopy and X-ray Microanalysis”, P T R Prentice -Hall, New York (1993).
51.L. J. Van der Pauw, Philips Res. Reports, 13, p.1 (1985).
52.D. C. Marra, E. S. Aydil, S. J. Joo, E. Yoon, and V. I. Srdanov, Appl. Phys. Lett. 77, 3346 (2000).
53.I. H. Kim, H. S. Park, Y. I. Park, and T. Kim, Appl. Phys. Lett. 73, 1634 (1998).
54.B. Heying, X. H. Wu, S. Keller, Y. Li, D. Kapolnek, B. P. Keller, S. P. DenBaars, and J. S. Speck, Appl. Phys. Lett. 68, 643 (1996).
55.T. Ide, M. Shimizu, X. Q. Shen, K. Jeganathan, H. Okumura, and T. Nemoto, J. Cryst. Growth 245, 15 (2002).
56.H. K. Cho, Ph.D. dissertation, KAIST, Tokyo, pp. 143-227 (2001).
57.H. D. Li, M. Tsukihara, Y. Naoi, Y. B. Lee, and S. Sakai, Appl. Phys. Lett. 84, 1886 (2004).
58.K. S. Son, D. G. Kim, H. K. Cho, K. Lee, S. Kim, and K. Park, J. Cryst. Growth 261, 50 (2004).
59.A. M. Sanchez, M. Gass, A. J. Papworth, P. J. Goodhew, P. Singh, P. Ruterana, H. K. Cho, R. J. Choi, and H. J. Lee, Thin solid films 479, 316 (2005).
60.D. Huang, M. A. Reshchikov, F. Yun, T. King, A. A. Baski, and H. Morkoc, Appl. Phys. Lett. 80, 216 (2002).
61.J. A. Grenko, C. L. Reynolds, Jr., R. Schlesser, J. J. Hren, K. Bachmann, Z. Sitar, and P. G.. Kotula, J. Appl. Phys. 96, 5185 (2004).
62.S. K. Hong, T. Yao, B. J. Kim, S. Y. Yoon, and T. I. Kim, Appl. Phys. Lett. 77, 82 (2000).
63.D. D. Perovic, C. J. Rossouw, and A. Howie, Ultramicroscopy 52, 353 (1993).
64.T. Saito and Y. Arakawa, Physica E 15, 169 (2002).
65.V. Fiorentini, F. Bernardini, and O. Ambacher, Appl. Phys. Lett. 80, 1204 (2002).
66.E. M. Wong, J. E. Bonevich, and P. C. Searson, J. Phys. Chem. 102, 7770 (1998).
67.M. Suzuki, T. Uenoyama, and A. Yanase, Phys. Rev. B 52, 8132 (1995).
68.D. Fritsch, H. Schmidt, and M. Grundmann, Phys. Rev. B 67, 235205 (2003).
69.Y. C. Yeo, T. C. Chong, and M. F. Li, J. Appl. Phys. 83, 1429 (1998).
70.T. V. Shubina, S. V. Ivanov, V. N. Jmerik, and D. D. Solnyshkov, Phys. Rev. Lett. 92, 117407 (2004).
71.H. K. Cho, J. Y. Lee, N. Sharma, and C. J. Humphreys, Appl. Phys. Lett. 79, 2594 (2001).
72.Y. S. Lin, K. J. Ma, and C. C. Yang, J. Cryst. Growth 242, 35 (2002).
73.M. Shimotomai and A. Yoshikawa, Appl. Phys. Lett. 73, 3256 (1998).
74.Y. S. Lin, K. J. Ma, C. Hsu, Y. Y. Chung, C. W. Liu, S. W. Feng, Y. C. Cheng, C. C. Yang, H. W. Chuang, C. T. Kuo, J. S. Tsang, and T. E. Weirich, Appl. Phys. Lett. 80, 2571 (2002).
75.P. G. Eliseev, P. Perlin, J. Lee, and M. Osinski, Appl. Phys. Lett. 71, 569 (1997).
76.D. A. B. Miller, D. S. Chemla, T. C. Damen, A. C. Gossard, W. Wiegmann, T. H. Woodand, and C. A. Burrus, Phys. Rev. B 32, 1043 (1985).
77.T. Wang, D. Nakagawa, J. Wang, T. Sugahara, and S. Sakai, Appl. Phys. Lett. 73, 3571 (1998).
78.T. Kuroda and A. Tackeuchi, Appl. Phys. Lett. 92, 3071 (2002).
79.Y. P. Varshni, Physica 34, 149 (1967).
80.W. Shan, T. J. Schmidt, X. H. Yang, S. J. Hwang, J. J. Song, and B. Goldenberg, Appl. Phys. Lett. 66, 985 (1995).
81.W. Shan, B. D. Little, J. J. Song, Z. C. Feng, M. Schurman, and R. A. Stall, Appl. Phys. Lett. 69, 3315 (1996).
82.D. Bimberg, M. Sondergeld, and E. Grobe E, Phys. Rev. B 4, 3451 (1971).
83.J. I. Pankove, “Optical Processes in semiconductors”, pp. 34-86 and 370-390, Dover, New York (1971).
84.M. Leroux, N. Grandjean, B. Beaumont, G. Nataf, F. Semond, J. Massies, and P. Gibart, J. Appl. Phys. 86, 3721 (1999).
85.E. M. Goldys, M. Godlewski, R. Langer, A. Barski, P. Bergman, and B. Monemar, Phys. Rev. B 60, 5464 (1999).
86.K. L. Teo, J. S. Colton, P. Y. Yu, E. R. Weber, M. F. Li, W. Liu, K. Uchida, H. Tokunaga, N. Akutsu, and K. Matsumoto, Appl. Phys. Lett. 73, 1697 (1998).
87.W. Gotz, N. M. Johnson, C. Chen, H. Liu, C. Kuo, and W. Imler, Appl. Phys. Lett. 68, 3144 (1996).
88.S. W. Feng, Y. C. Cheng, Y. Y. Chung, C. C. Yang, M. H. Mao, Y. S. Lin, K. J. Ma, and J. I. Chyi, Appl. Phys. Lett. 80, 4375 (2002).
89.L. T. Romano, J. E. Northrup, A. J. Ptak, and T. H. Myers, Appl. Phys. Lett. 77, 2479 (2000).
90.H. K. Cho and G. M. Yang, Appl. Surf. Sci. 200, 138 (2002).
91.G. Martinez-Criado, A. Cros, A. Cantarero, N. V. Joshi, O. Ambacher, and M. Stutzmann, Solid-State Electronics 47, 565 (2003).
92.L. Dongsheng, M. Sumiya, S. Fuke, D. Yang, D. Que, Y. Suzuki, and Y. Fukuda, J. Appl. Phys. 90, 4219 (2001).
93.Y. Narukawa, Y. Kawakami, S. Fujita, and S. Nakamura, Phys. Rev. B 59, 10283 (1997).