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標題: 以不同圖形化之藍寶石基板應用於氮化鎵發光二極體之研究
A Study on the Application of Different Patterned Sapphire Substrate for GaN Light-Emitting Diodes
作者: 曾介南
Tseng, Chieh-Nan
關鍵字: 藍寶石圖形化基板;Pattern Sapphire Substrate
出版社: 光電工程研究所
引用: [1]林佳裕, 國立中央大學光電科學與工程學系碩士論文,2009年 [2]S. Youshida, S. Misawa,and S. Gonda, “Improvements on the electrical and luminescent properties of reactive molecular beam epitaxially grown GaN film by using AIN- coated sapphire ”.Appl. Phys. Lett., vol. 42, pp. 427, 1983. [3]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 film frown on sapphire substrate by MOVPE,” Journal of Crystal Growth, Vol. 98, pp. 209, 1989. [4]S. Nakamura, ”GaN growth using GaN buffer layer” Japanese Journal of Applied Physics Part 2-Letters, Vol. 30, pp. L1705, 1991. [5]H. W. Huang, C. C. Kao, J. T. Chu, H. C. Kuo, S. C. Wang and C. C. Yu, “Improvement of InGaN–GaN Light- Emitting Diode Performance With a Nano-Roughened p-GaN Surface”, IEEE Plot. Tech. Lett., vol. 17, pp. 983, 2005. [6]S. Nakamura, M. Senoh, and T. Mukai ,”Highly p-type Mg- doped GaN film grown with GaN buffer layer” Japanese Journal of Applied Physics, Vol. 30, pp. L1708, 1991. [7] [8]李克濤,國立中央大學光電科學與工程學系碩士論文,2007年 [9]吳麗雲,國立中央大學機械工程研究所碩士論文,2006年 [10]S. Nakamura, T. Mukai and M. Senoh, “Candela-class high-brightness InGaN/AlGaN double-heterostructure blue light-emitting diodes”, 47Appl. Phys. Lett., vol. 64, 1687, 1994. [11]陳怡如,國立中央大學化學工程與材料工程研究所碩士論文, 2007年 [12]B. Heying, X. H. Wu, S. Keller, Y. Li, D. Kapolnek, B. P. Keller, S. P. Denbaars and J. S. Speck, “Role of threading dislocation structure on the x-ray diffraction peak widths in epitaxial GaN films”, Appl. Phys.Lett., vol. 68, 643, 1996. [13]Bhattacharya , “Semiconductor Optoelectric Devices”, Prentice Hall [14]D. Hull , ‘‘Introduction to Dislocations’’, 2nd Edition. Pergamum Press, Oxford. [15]S. M. Sze, “Physics of Semiconductor Devices,” 2nd ed., Ch. 2,Wiley, New York, 1981. [16] facture/Nanotech/Web/ch4.htm [17] facture/Nanotech/Web/ch4.htm [18]陳隆建,「發光二極體之原理及製程」,全華科技圖書股份 有限公司印行,2007年
本研究利用濕蝕刻圖形化、乾蝕刻圖形化及二次蝕刻圖形化藍寶石基板製作成藍色發光二極體,並使用掃描式電子顯微鏡( SEM )觀察於不同圖形化基板製程所製作出之圖形尺寸、蝕刻深度及圖形形貌差異。另外,在藍色發光二極體光電特性的部份,我們使用電阻量測系統( TLM )量測電流-電壓( I-V Curve )及漏電流( Ir )、使用自動點測機( Prober )量測波長對應光強度[ Wavelength – Power( mW ) ]、使用光譜儀量測光分佈( Current Spreading )及使用積分球量測晶粒封裝( Ag-TO )光強度之差異比較。
在圖形化藍寶石基板製程實驗設計方面,我們共設計三組製程別來進行比較,製程組別[一]:濕蝕刻圖形化製程之不同圖形尺寸及蝕刻深度、製程組別[二]:乾蝕刻與濕蝕刻圖形化製程之相同圖形尺寸及蝕刻深度、製程組別[三]:二次濕蝕刻與濕蝕刻圖形化製程之相同圖形尺寸及蝕刻深度。經實驗結果在實驗中發現取決於亮度的優劣,主要在於圖形尺寸( 即為圖形分布密度 )、蝕刻深度及圖形的斜角度。蝕刻深度越深、圖形尺寸越小、斜角度越大及斜角度數量增加都有助於提升藍色發光二極體之光強度。但我們從實驗的另一方面又可得知,雖然乾蝕刻製程具有相當的穩定性及蝕刻均勻性,但仍有成本較高、產能少及蝕刻選擇比不易控制之缺點。從二次濕蝕刻製程發現,在同一圖形尺寸及蝕刻深度的條件下,二次濕蝕刻製程藉由改變圖形的斜角度及數量與濕蝕刻製程相比,光強度提升至5~7% ( 5mW~7mW )且漏電流降低約23 nA。若與乾蝕刻製程相比,光強度提升至8% ( 8mW )。由此可知改變圖形斜角度及增加斜角度數量可有效增加光取出之效益,相對也提升光強度。最後,也驗證出藍寶石基板圖形化製程以二次濕蝕刻製程製作於藍色發光二極體具有最佳之光電特性及提升光強度效率。

In this research, the patterned sapphire substrates, were fabricated by the dry etching、wet etching and two-step wet etching and were used to make the blue ray LED respectively. And the SEM was used to inspect the pattern size, etching depth and pattern morphology in these processes. Besides, the optical and electrical properties, such as forward I-V curve、leakage current, the relationships between the wavelength and power, the current spreading and output power of Ag-TO packaging, were measured by the TLM system、prober、spectrometer and integrating sphere to compare the difference between these processes.
We designed three different conditions to investigate the properties among these processes. According to the experiment results, the luminance was mainly determined by the pattern size, etching depth and taper. The large etching depth and pattern taper, and the smaller pattern size would improve the luminance of a blue ray LED. The dry etching process had a better stability and etching uniformity, but it also suffered some disadvantages such as higher cost, less capacity and more difficult to control the selectivity. As compared with the wet etching process, we also found out that the output power could be improved about 5 to 7 % and the leakage current could decrease about 23nA in the secondary wet etching one by changing the number and angle of etching pattern: Besides to compare with dry etching process, the output power could be improved about 8%. In conclusion, the efficiency of the blue ray LED on patterned sapphire substrate fabricated by the two-step wet etching process could be improve by changing the pattern taper and increasing the number of the taper to achieve the better optical and electrical properties.
其他識別: U0005-0102201304094200
Appears in Collections:光電工程研究所

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