本研究以開發圖像顯示用單石化(Monolithic)微型發光二極體(LED)陣列，希望呈現出64 × 64之行列選址式(Row-Column-Addressed)微型LED陣列。並希望未來能結合IC發展成主動式的微型LED陣列，可應用在微影像顯示、無光罩微影(Maskless Photolithography)、光驅基因工程(Optogenetics)等領域。
我們研究開發380nm(紫外光)和450nm(藍光)微型LED陣列，而隨著畫素微縮，載子復合產生之輻射越易離開晶體，因此可以預期輻射場將朝等向性趨近，亦即廣角化。然此廣角化對圖像顯示用之 LED 陣列勢必造成光互擾(Optical Crosstalk)影響圖像品質。而我們64 × 64微型LED陣列的理想封裝架構為採用覆晶技術，亦即顯示圖案將由晶背，即自 Sapphire 面輸出。Sapphire (折射率 ~ 1.8)相對空氣具有較高之折射率,光束折射不似自GaN(n ~ 2.4)進入空氣般有嚴重偏折，但單一畫素所發出之光束，於 Sapphire 內仍漸行漸散，且隨晶背厚度增加，發散影響鄰近畫素程度愈嚴重因此可以預期隨著畫素數量與密度的提高，基板厚度勢必越來越薄，甚至完全移除 (例如採用Laser Lift-Off，LLO 技術)。除盡量提升減薄規格外(基本厚度上限為 100 μm), 亦開發微透鏡陣列技術抑制畫素光束之發散。

In this study, we will develop monolithic micro-light-emitting diodes array (mLEDA) for pattern display, and perform a 64 x 64 row-column-addressed micro-light-emitting diodes array, which have advanced applications in micro-projector, mask-less photolithography, and optogenetics.
We will develop 380 nm and 450 nm mLEDAs in this study. By using the flip-chip bonding technology, the light is come out from the back side of wafer, which is sapphire face, but the light will deflect between the interface of GaN (n~2.4) and sapphire (n~1.8) because of different refractive index, and the light will diverge passing through the sapphire. The large sapphire thickness leads to optical cross-talk, so the light will interfere the adjacent pixels. Thus, the higher density of pixels, the thinner sapphire thickness we need, or we can remove the sapphire by Laser Lift-Off. We also develop micro-lens array technology to focus the light and restrict the divergence of light in our design.

CONTENTS
口試委員會審定書---------------------------------------------------------------#
誌謝------------------------------------------------------------------------------i
中文摘要-------------------------------------------------------------------------ii
ABSTRACT---------------------------------------------------------------------iii
CONTENTS--------------------------------------------------------------------iv
LIST OF FIGURES-------------------------------------------------------------vi
LIST OF TABLES--------------------------------------------------------------viii
Chapter 1 Introduction---------------------------------------------------------1
1.1 Development of III-nitride-based light-emitting diodes----------------1
1.2 Motivation and purpose--------------------------------------------------4
Chapter 2 The Basis of Theory and Characterization Instruments----------7
2.1 Basic theory of light-emitting diodes-----------------------------------7
2.2 Theory of current crowding in LEDs-----------------------------------10
2.3 Characterization analysis instruments---------------------------------15
2.3.1 Current-Voltage I-V Characterization measurement system---------------------------------------------------------------------------------------16
2.3.2 Luminous Intensity (L-I) measurement---------------------------16
2.3.3 Electroluminescence (E-L) measurement system---------------17
2.3.4 NKT Reflection and Transmission measurement----------------18
Chapter 3 Micro-LEDs Arrays Device Structure and Fabrication----------22
3.1 Epitaxial structure design concept------------------------------------22
3.2 The design of Mask-----------------------------------------------------23
3.3 Experiment process of Microlens--------------------------------------23
3.4 Experiment process of Reflector---------------------------------------25
3.5 Experiment process of micro-LED arrays-----------------------------26
Chapter 4 Result and Discussion--------------------------------------------38
4.1 Fabrication Process of 64*64 micro-LED Arrays----------------------38
4.1.1 P-contact layer ----------------------------------------------------38
4.1.2 The results of Reflectors------------------------------------------42
4.1.3 The results of Passivation、Isolation and Flip chip Bonding--------------------------------------------------------------------------------------45
4.2 The results of Microlens------------------------------------------------46
4.2.1 The formation of microlens---------------------------------------46
4.2.2 Microlens arrays on 64*64 mLED arrays-------------------------50
4.3 Electro-optical characteristics of mLEDAs----------------------------60
4.3.1 I-V characteristics analysis of mLEDs---------------------------60
4.3.2 Electroluminescence (EL) Spectrum of mLED Arrays-----------68
4.3.3 Luminous Intensity (L-I) of violet mLEDs------------------------69
4.3.4 Divergence angle of mLEDAs------------------------------------71
Chapter 5 Conclusions-------------------------------------------------------72
REFERENCE------------------------------------------------------------------76

[1] CBS interactive incorporated, http://www.himaxdisplay.com/en/product/info.asp
[2] Texas instruments, http://www.dlp.com/technology/default.aspx
[3] Industrial Technology Research Institute, newsletter no. 10005, 2011
[4] J. Day, J. Li, D. Y. C. Lie, C. Bradford, J. Y. Lin and H. X. Jiang, “Full-scale self-emissive blue and green microdisplays based on GaN micro-LED arrays,” Proc. of SPIE, vol. 8268, 82681X, 2012
[5] C. W. Jeon, E. Gu and M. D. Dawson, “Mask-free photolithographic exposure using a matrix-addressable micropixellated AlInGaN ultraviolet light-emitting diode,” Appl. Phys. Lett., 86, 221105, 2005
[6] D. Elfström,B. Guilhabert, J. McKendry, S. Poland, Z. Gong, D. Massoubre, E. Richardson, B. R. Rae, G. Valentine, G. Blanco-Gomez, E. Gu, J.M. Cooper, R.K. Henderson and M.D. Dawson, “Mask-less ultraviolet photolithography based on CMOS-driven micro-pixel light emitting diodes,” Opt. Express, vol. 17, no. 26, pp.23522-23529, 2009
[7] H. X. Zhang, D. Massoubre, J. McKendry, Z. Gong, B. Guilhabert, C. Griffin, E. Gu, P. E. Jessop, J. M. Girkin and M. D. Dawson, “Individually-addressable flip-chip AlInGaN micropixelated light emitting diode arrays with high continuous and nanosecond output power,” Opt. Exp., vol. 16, no. 13, pp.9918-9926, 2008
[8] C. Griffin, E. Gu, H. W. Choi, C. W. Jeon, J. M. Girkin, M. D. Dawson and G. McConnell, “Beam divergence measurements of InGaN/GaN micro-array light-emitting diodes using confocal microscopy,” Appl. Phys. Lett., 86, 041111, 2005
[9] S. Nakamura, M. Senoh, and T. Mukai, ‘‘p-GaN/n-InGaN/n-GaN double-heterostructure blue-light-emitting diodes,’’ Jpn. J. Appl. Phys., vol. 32, pp. L8–L11, 1993
[10] E. Fred Schubert, "Light-Emitting Diodes", (2003)
[11] J. Z. Liu, C. H. Lin, K. Y. Lee, Y. L. Wang, C. L. Liao, Y. F. Chang, C. L. Ho, and M. C. Wu, ‘‘Performance Enhancement of Ultraviolet Light-Emitting Diodes by Incorporating a Thin Al(In)GaN Interlayer in Multi-Quantum-Well Region,’’ Quantum Electronics, IEEE, Vol. 51, Issue 7, 2015
[12] J. Z. Liu, Martin D. B. Charlton, C. H. Lin, K. Y. Lee, Chirenjeevi Krishnan, and M. C. Wu, “Efficiency Improvement of Blue LEDs Using a GaN Burried Air Void Photonic Crystal With High Air Filling Fraction,” Quantum Electronics, IEEE, Vol. 50, Issue 5, 2015
[13] W. K. Hong, J. O. Song, H. G. Hong, K. Y. Ban, T. Lee, J. S. Kwak, Y. Park and T. Y. Seong, “Highly reflective and low resistance indium tin oxide/Ag ohmic contacts to p-Type GaN for flip-chip light emitting diodes,” Electrochem. Solid-State Lett., 8 (11) G320-G323, 2005
[14] S. H. Huang, R. H. Horng and D. S. Wuu, “Improvements of n-side-up GaN light-emitting diodes performance by indium-tin-oxide/Al mirror,” Jpn. J. Appl. Phys., vol. 45, pp. 3449-3452, 2006
[15] H. G. Kim, P. Deb and T. Sands, “High-reflectivity Al-Pt nanostructured ohmic contact to p-GaN,” IEEE Trans. Electron Devices, vol. 53, no. 10, pp. 2448-2453, 2006
[16] L. B. Chang, C. C. Shiue and M. J. Jeng, “High reflective p-GaN/Ni/Ag/Ti/Au Ohmic contacts for flip-chip light-emitting diode (FCLED) applications,” Appl. Surf. Sci., 255 (12):4, 2009
[17] 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 (2001) 50–52, 2001
[18] S. H. Park, H. Jeon, Y. J. Sung, and G. Y. Yeom, “Refractive sapphire microlenses fabricated by chlorine-based inductively coupled plasma etching,” APPLIED OPTICS, Vol. 40, No. 22, 1 August, 2001
[19] K. H. Li, C. Feng, and H. W. Choi, “Analysis of micro-lens integrated flip-chip InGaN light-emitting diodes by confocal microscopy,” 2014 AIP Publishing LLC, published online 3 February, 2014
[20] K. I. Nakamatsu, M. Okada, C. Minari, Y. Takeuchi, N. Taneichi, S. Ohtaka, S. Matsui, “Effect of UV Irradiation on Microlens Arrays Fabricated by Room Temperature Nanoimprinting Using Organic Spin-on-Glass,” APL, published online May 23, 2008
[21] Pengfei Tian, Jonathan J. D. McKendry, Zheng Gong, Shuailong Zhang, Scott Watson, Dandan Zhu, Ian M. Watson, Erdan Gu, Anthony E. Kelly, Colin J. Humphreys, and Martin D. Dawson, “Characteristics and applications of micro-pixelated GaN-based light emitting diodes on Si substrates,”2014 AIP Publishing LLC, published online 21 January, 2014
[22] Y. C. Chu, M. H. Wu, C. J. Chung, Y. H. Fang, and Y. K. Su, Fellow, IEEE, “Micro-Chip Shaping for Luminance Enhancement of GaN Micro-Light-Emitting Diodes Array,” IEEE EDL, VOL. 35, NO. 7, JULY, 2014