臺灣博碩士論文加值系統

在本論文中主要利用實驗室自組水平式氫化物氣相磊晶系統 (Hydride Vapor Phase Epitaxy, HVPE) 成長氮化鎵厚膜，首先透過調整三五族氣體比例，有效改善因HVPE系統長速過快的特性所導致不平整的氮化鎵表面，並成功將此成長參數應用在具有濺鍍氮化鋁緩衝層的藍寶石基板之上，然而許多國內外的文獻中，明確指出發光二極體結構應用在圖案化藍寶石基板之上時，能夠大幅增加光萃取效率，並且有效降低缺陷密度，但尚未有人將此基板導入HVPE成長系統，因此我們再將此參數導入濺鍍氮化鋁/圖案化藍寶石基板上時，我們可以從光學顯微鏡下得知其表面有許多島狀氮化鎵(grain)分布，遂推測其成因在尚未將錐體圖案蓋過之前的長速過快，而讓氮化鎵在包覆圖案化錐體時，包覆地不均勻，進而在錐體圖案側邊出現諸多縫隙影響後續磊晶層的堆疊，而此問題透過MOCVD成長圖案化基板的經驗，成功利用兩段式成長法解決表面不平整問題，直至現在本實驗室已具有能力成長出表面平整的氮化鎵厚膜於濺鍍氮化鋁之圖案化藍寶石基板之上。因此利用HVPE成長氮化鎵厚膜除了能夠有效降低時間成本、加快氮化鎵厚膜基板生產外，還能在光電特性及熱特性上有明顯的提升。將上述樣品透過光學顯微鏡(OM)、掃描式電子顯微鏡(SEM)、X-ray繞射儀(XRD)、原子力顯微鏡(AFM)、以及量測單位面積缺陷密度(EPD)等方式，對材料的表面以及材料品質做進一步分析。
分析結果顯示利用HVPE成長厚膜氮化鎵的樣品在XRD量測氮化鎵(002)面或(102)面的半高寬皆比MOCVD成長氮化鎵薄膜在相同基板上來的窄，可由726 arcsecs降至325 arcsecs，而氮化鎵(102)面的半高寬則由574 arcsecs降至344 arcsecs。單位面積缺陷數亦可由1.7 x 108/cm2降至8.8 x 107/cm2，由此證明了氮化鎵膜厚越厚，其材料品質越佳。
接著將樣品應用於氮化鎵發光二極體元件，首先利用MOCVD成長氮化鎵發光二極體結構，再利用黃光微影製程技術製作成發光二極體元件後，並量測其光電特性和熱特性。可由前期研究得知利用HVPE成長之氮化鎵厚膜提升了氮化鎵材料的品質，接著利用MOCVD成長為發光二極體結構後，其內部量子效率提升了94%;且在LED元件之光輸出功率下增加了88.8%，另外也利用熱影像量測不同電流驅動下之發光二極體的熱分布，由於氮化鎵材料之導熱特性佳，故當氮化鎵磊晶層越厚時，發光元件的散熱效率比厚度薄之樣品更容易將熱導出，大幅降低了熱效應，因此提升了飽和電流值，可由300mA提升至最高為405mA。由此知道以HVPE成長的氮化鎵厚膜於濺鍍氮化鋁之圖案化藍寶石基板所製作的發光二極體元件，可有效提升光輸出功率以及改善元件散熱能力。

In this thesis, we used a horizontal home-made hydride vapor phase epitaxy (HVPE) to grow thick GaN layers on a sputtered AlN/patterned sapphire substrate. We initially optimized surface morphology and crystal quality by changing the V-III ratio to acquire a smooth surface. Next, we attempted to induce the sputtered AlN into becoming a buffer layer to realize one-step growth in HVPE and then applied this technique to the patterned sapphire substrate. Results showed that the GaN films grown on the patterned sapphire substrate had a rough surface. Thus, we induced a two-step growth epitaxy technology and successfully improved the morphology and quality of the GaN film. We then used optical microscopy, scanning electron microscopy, X-ray diffraction, atomic force microscopy, and transmission electron microscopy to measure surface morphology, epitaxial layer thickness, and crystal quality. The 10 μm-thick GaN template had lower etching pit density (from 1.7108 cm−1 to 8.8107 cm−1) and smaller FWHM (from 726 arcsecs to 325 arcsecs) than the 2 μm-thick GaN template from MOCVD.
We also applied a thick GaN template to GaN-based light-emitting diodes (LEDs). Compared with the light output power of the LED device grown on the 2 μm-thick GaN template, that of the LED device grown on the 10 μm-thick GaN template was enhanced by 89% at an injection current of 20 mA. The saturation current of the LED device grown on the 10 μm-thick template also improved from 300 mA to 405 mA when compared with that of the LED device grown on the 2 μm-thick GaN template. These results can be explained through thermal imaging. This thesis provides a suitable GaN template for LED devices.

目錄

摘要 i
英文摘要(Abstract) iv
致謝 v
目錄 vi
表目錄 x
圖目錄 xi
第一章 序論 1
第二章 實驗原理與量測系統 4
2.1 氫化物氣相磊晶機台介紹 4
2.2 實驗原理 6
2.2.1 氫化物氣相磊晶成長原理 6
2.2.2 圖案化基板對氮化鎵磊晶成長之影響 7
2.2.3 圖案化基板對光散射之影響 9
2.2.4 濺鍍氮化鋁緩衝層對氮化鎵磊晶成長之影響 10
2.3 量測儀器介紹 11
2.3.1 掃描式電子顯微鏡 11
2.3.2 1X-ray繞射儀 12
2.3.3 原子力顯微鏡 12
2.3.4 光激發螢光光譜量測系統 13
2.3.5 電流-電壓量測系統 13
2.3.6 積分球量測系統 13
2.3.7 光強度量測系統 14
第三章 以氫化物氣相磊晶系統成長未摻雜氮化鎵厚膜基板實驗方法與步驟 15
3.1 前言 15
3.2 成長未摻雜氮化鎵於濺鍍氮化鋁/藍寶石基板上之實驗 16
3.2.1 實驗動機 16
3.2.2 實驗流程與結果分析 17
3.3 成長未摻雜氮化鎵於濺鍍氮化鋁/圖案化藍寶石基板上之實驗 18
3.3.1 實驗動機 18
3.3.2 實驗流程與結果分析 19
3.4 利用兩段式成長法成長未摻雜氮化鎵於濺鍍氮化鋁/圖案化藍寶石
基板上之實驗 20
3.4.1 實驗動機 20
3.4.2 實驗流程與結果分析 20
3.5 氮化鎵發光二極體元件之製程 23


第四章 以氫化物氣相磊晶系統成長未摻雜氮化鎵於鍍有氮化鋁緩衝層/圖案化藍寶石基板上的表面形貌與材料分析 26
4.1 氮化鎵厚膜之掃描式電子顯微鏡量測分析 26
4.2 氮化鎵厚膜之X-ray繞射儀量測分析 27
4.3 氮化鎵厚膜之單位面積缺陷密度量測分析 28
4.4 氮化鎵厚膜之穿透式電子顯微鏡量測分析 29
4.5 氮化鎵厚膜之拉曼散射儀量測分析 30
4.6 結果分析與討論 31

第五章 氮化鎵二極體薄膜成長於濺鍍氮化鋁/圖案化藍寶石基板之光電特性分析34
5.1 氮化鎵二極體薄膜之光激發螢光光譜量測分析 34
5.1.1 氮化鎵二極體薄膜之低溫光激發螢光光譜量測分析 34
5.2 氮化鎵發光二極體元件之光電特性分析 36
5.2.1 氮化鎵發光二極體元件之電流-電壓量測分析 36
5.2.2 氮化鎵發光二極體元件之發散角量測分析 37
5.2.3 氮化鎵發光二極體元件之光輸出功率-電流量測分析 37
5.2.4 氮化鎵發光二極體元件之熱影像儀量測分析 39
5.2.5 氮化鎵發光二極體元件之Hot/Cold factor分析 40
5.2.6 氮化鎵發光二極體元件之二維影像量測分析 41

第六章 結論與未來工作 42
參考文獻 46

[1] H. Amano, N. Sawaki, I. Akasaki, T. Y. Oyoda, “Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer,” Appl. Phys. Lett., vol. 48, no. 5, pp. 353-354, Feb. 1986.

[2] S. Nakamura, Jpn. J. “In Situ Monitoring of GaN Growth Using Interference Effects,” Appl. Phys., vol. 30, no. 8, pp. 1620-1627, Aug. 1991.

[3] O. H. Nam, M. D. Bremser, T. S. Zheleva, and R. F. Davis, ’’Lateral epitaxy of low defect density GaN layers via organometallic vapor phase epitaxy,” Appl. Phys. Lett., vol. 71 no.18, pp. 2638-2640, Nov. 1997.

[4] D. S. Wuu, et al., “Defect reduction and efficiency improvement of near- ultraviolet emitters via laterally overgrown GaN on a GaN/patterned sapphire template,” Appl. Phys. Lett., vol. 89, no. 16, pp. 161105-1–161105-3, Oct. 2006.

[5] Mei-Tan Wang, Frank Brunner, Kuan-Yung Liao, Yun-Li Li, Snow H. Tseng , Markus Weyers. “Optimization of GaN wafer bow grown on cone shaped patterned sapphire substrates,” J. Crystal Growth., vol. 363, pp. 109–112, Oct. 2013.

[6] Hsin-Hsiung Huang , Chu-Li Chao, Tung-Wei Chi, Yu-Lin Chang, Po-Chun Liu, Li-Wei Tu, Jenq-Dar Tsay, Hao-Chung Kuo, Shun-Jen Cheng, Wei-I Lee, “Strain-reduced GaN thick-film grown by hydride vapor phase epitaxy utilizing dot air-bridged structure,” J. Crystal Growth. vol. 311, pp. 3029–3032, May. 2009.

[7] Y. Kato, S. Kitamura, K. Hiramatsu and N. Sawaki, “Selective growth of wurtzite GaN and AlxGa1−xN on GaN/sapphire substrates by metalorganic vapor phase epitaxy,” J. Crystal Growth., vol. 144, no. 3–4, pp. 133–140, May. 1994.

[8] B. Lengeler, U. Klemradt, “Development of Nanofocusing Refractive X-Ray Lenses.”

[9] Chi-Hsun Hsieh, “InGaN Ultraviolet Light-Emitting Diodes Grown on Patterned Sapphire Substrates,” Jul. 2007.

[10] Y.J. Sung, H.S. Kim, Y.H. Lee, J.W Lee, S.H. Chae, Y.J. Park, G.Y. Yeom,“High rate etching of sapphire wafer using Cl2/BCl3/Ar inductively coupled plasmas,” Materials Science and Engineering B82, pp. 50–52, 2001.

[11] 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 Transaction On Electron Devices, vol. 57, no. 1, Jan. 2010.

[12] E. Fred Schubert, “Light-emitting diodes”, second edition, pp. 133–138.

[13] J. J. Chen, Y. K. Su, Fellow, IEEE, C. L. Lin, S. M. Chen, W. L. Li, and C. C. Kao, “Enhanced Output Power of GaN-Based LEDs With Nano- Patterned Sapphire Substrates,” IEEE Photonics Technology Letters, vol. 20, no. 13, Jul. 2008.

[14] H. Amano, I. Akasaki, K. Hiramatsu, N. Koide and N. Sawaki, “Effects of the buffer layer in metalorganic vapour phase epitaxy of GaN on sapphire substrate,” Thin Solid films., vol. 163, pp. 415–420, Sep. 1988.

[15] K. Hiramatsu, et al., “Growth mechanism of GaN grown on sapphire with AlN buffer layer by MOVPE,” J. Crystal Growth., vol. 115, no. 1–4, pp. 628–633, Dec. 1991.

[16] H. Amano, N. Sawaki, I. Akasaki, and Y. Toyoda, “Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer,” Appl. Phys. Lett., vol. 48, no. 5, pp.353–355, Feb. 1986.

[17] 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 (0
[18] C. H. Yen, et al., “GaN-based light-emitting diode with sputtered AlN nucleation layer,” IEEE Photon. Technol. Lett., vol. 24, no. 4, pp. 294–296, Feb. 2012.

[19] Hai-Ping Liu, “Study of GaN Crystals Growth on Patterned Sapphire Substrate by Hydride Vapor Phase Epitaxy Method.”

[20] Hui-Youn Shin, Y. I. Chang, S. K. Kwon, K. T. Lee, M. J. Cho and K. H.Park,” The Growth Characteristics of a GaN Layer on a Cone-Shaped Patterned Sapphire Substrate by TEM Observation,” Journal of the Korean Physical Society, vol. 50, no. 4, pp. 1147_1151, Apr. 2007.

[21] Woei-Kai Wang, Dong-Sing Wuu, Wen-Chung Shih, Jau-Shing Fang, “Near-Ultraviolet InGaN/GaN Light-Emitting Diodes Grown on Patterned Sapphire Substrates,” Japanese Journal of Applied Physics vol. 44, no. 4B, pp. 2512–2515, 2005.

[22] Hung-Ming Chang, Wei-Chih Lai, and Shoou-Jinn Chang, ” Effects of Initial GaN Growth Mode on Patterned Sapphire on the Opto-Electrical Characteristics of GaN-Based Light-Emitting Diodes,” Journal Of Display Technology, vol. 9, no. 4, Apr. 2013.

[23] Z. Liliental-Weber, J. Jasinski, J. Washburn, “Comparison between structural properties of bulkGaN grown in liquid Ga under high N pressure and GaN grown by other methods,” J. Crystal Growth ,vol. 246, pp. 259–270, 2002.

[24] S. Watanabe, et al., “Internal quantum efficiency of highly-efficient InxGa1-xN-based near-ultraviolet light-emitting diodes,” Appl. Phys. Lett., vol. 83, no. 24, pp. 4906–4908, Dec. 2003.

[25] Cheng-Huang Kuo, Li-Chuan Chang, and Hsiu-Mei Chou, “Current Spreading Improvement in GaN-Based Light-Emitting Diode Grown on Nano-Rod GaN Template,” IEEE Photonics Technology Letters, vol. 24, no. 7, Apr. 2012.

[26] Yu-shan Hsiao,” Growth of Thick GaN Layers on GaN Nanorod Template by HVPE,” Jun. 2010.

[27] O. Madelung, Semiconductors: Data Handbook, 2003.

[28] 李政鴻 二元與四元位障層應用於氮化銦鎵綠光二極體之光性分析 國
立中央大學 電機工程學系碩士論文 中華民國91年6月