臺灣博碩士論文加值系統

新穎透明導電材料─銦鋅氧化物(Indium-Zinc-Oxide，IZO)─是近年來在學術界被熱烈研究的一種化合物半導體電極材料。由於IZO薄膜具有高穿透率、低電阻率、以及均勻的蝕刻性，因此非常適合應用於光電元件，例如各種平面顯示器的透明電極、發光二極體的透明導電層、太陽能電池、光電偵測器等，深具應用發展潛力。
於本研究中，我們係利用RF濺鍍法成長IZO薄膜，並針對所得薄膜進行光、電特性量測與分析。藉由濺鍍參數之調變，所得室溫下之最佳電阻率為3.69�e10-4 �-cm2，於可見光區域內(400-800nm)平均穿透率為80%以上。IZO薄膜經霍爾(Hall)量測顯示係為一n型高濃度材料。我們亦嘗試將IZO膜在氮氣或氧氣環境下進行熱處理，實驗結果顯示3000Å厚度的IZO薄膜於藍光波長區間具有92%的穿透率，經氧氣環境下熱處理後IZO之電阻率會大幅提高，並據原子力顯微鏡AFM測得其表面粗糙度亦呈現大幅增加，而穿透率之波峰於頻譜上則顯現出紅移位現象。
於應用方面，本論文旨在利用IZO薄膜作為GaN基LEDs之透明導電層(TCL)以增加發光效率。我們分析IZO/p-GaN之接觸特性，實驗結果顯示其為蕭基接觸。於使用一薄金(45Å)/鎳(25Å)以及鎳(50Å)作為IZO與p-GaN間之披覆層並以熱處理方式來改善其接觸特性，實驗結果發現若先將金/鎳/p-GaN適當氧化再於其上成長IZO膜，將可獲得良好的歐姆接觸特性。
於GaN基發光二極體之實作方面，與傳統金鎳製程比較，本論文所提以IZO(3000Å)/氧化-金(45埃Å)/鎳(25Å)/p-GaN之製程，於20mA導通電流條件下，據L-I特性分析其光輸出功率增加30%；另據I-V特性分析，順向電壓則增加0.5伏特；而據�d-I特性分析，採用IZO薄膜後元件之主波長�d於藍光區間發生紅移效應。

In this thesis Indium-Zinc-Oxide (IZO) layers prepared by RF sputtering were investigated. By suitable adjusting the deposition condition, the IZO films have an optimum resistivity of 3.69�e10-4 �-cm and an average transparency of 80% in visible light range (400-800nm). Based on Hall measurement it indicates that the obtained IZO film is essentially n-type and with a high carrier concentration. After thermal annealing in N2 or O2 ambient for 5-15 min, according to AFM measurement, both resistivity and surface roughness were seen increasing substantially, especially in O2 ambient. In addition, an obvious shift in the peak of transmittance was observed.
Experimental current-voltage characteristics show that IZO/p-GaN is a Schottky contact even after thermal annealing at elevated temperature in either N2 or O2 ambient. To improve the contact property, a thin Au(45Å)/Ni(25Å) or Ni(50Å) layer is then employed in this work to serve as a cladding layer between IZO and p-GaN. Experimental results revealed that the IZO(3000Å)/oxidized-Au(45Å)/Ni(25Å)/p-GaN contact system has a specific contact resistivity (SCR) of 4.85×10-2 Ω-cm and a transparency of 73-75% in the wavelength of 465-475 nm. As compared to the case without the IZO layer, at a forward current of 20 mA, about 30% improvement in light output power (LOP) of GaN-based LEDs has been obtained.

CONTENTS
Abstract (Chinese)
Abstract
Figure Captions
Table lists
Chapter 1.Introduction…………………………… 1
1.1 The basic properties of IZO material …………………… 1
1.2 The comparisons of properties between IZO and ITO material……… 3
1.3 Motivation………………………………… 4
Chapter 2… The preparation and characteristic of In2O3-ZnO (IZO) films by RF sputtering …………………5
2.1 The sputter system and basic properties of IZO film ………… 5
2.1.1 RF sputter system …………………………… 5
2.1.2 The electrical property of IZO film …………………… 7
2.1.3 The optical property of IZO films ………………… 8
2.2 Process flow of the IZO films ……………………… 10
2.2.1 Cleaning process ………………………………10
2.2.2 Sputtering parameters ………………………… 13
2.2.3 Thermal annealing process …………………………… 14
2.3 Material property analysis…………………………15
2.3.1 The electrical property analysis……………………17
2.3.2 The optical property analysis………………………………… 25
2.3.3 ESCA analysis…………………………… 28
2.3.4 AFM analysis……………………………… 28
Chapter 3. Investigation of IZO film contact to GaN-based LEDs ……………………………… 30
3.1 Introduction…………………………………… 35
3.1.1 Key issues of GaN-based LEDs…………………… 30
3.1.2 Contact resistivity measurement using CTLM………… 33
3.2 The electrical characteristic of IZO/p-GaN contact…………35
3.3 The use of a cladding layer between IZO and p-GaN……………………………… 38
3.3.1 The IZO/Au/Ni contact to p-GaN………………… 39
3.3.2 The IZO/Ni contact to p-GaN………………… 42
Chapter 4. The Fabrication of GaN-based LEDs and application of IZO film…………………… 44
4.1 The process flow for GaN-based LEDs fabrication………… 44
4.2 Measurements and discussions……………………… 49
4.3.1 L-I measurement……………………………49
4.3.2 I-V measurement……………………………… 50
4.3.3 d-I measurement…………………………… 51
Chapter 5. Conclusions……………………………… 53
References…………………………………… 55
誌謝…………………………………………………………… 57
自傳……………………………………………… 58

□1□ K. L. Chopra, S. Major, and D.K. Pandya, Thin Solid Films, vol 102, pp. 1 (1983)
□2□ H. Un’no, N. Hikuma, T. Omata, N. Ueda, T. Hashimoto, and H. Kawazoe, Jpn. J. Appl. Phys., Part 2, vol 32, L1260.
□3□ H. Enoki, T. Nakayama, and J. Echigoya, Phys. Status Solidi A, vol 129, pp. 181(1992).
□4□ R. J. Cava, J. M. Phillops, J. Kwo, G. A. Thomas, R. B. van Dover, S. A. Cater, J. J. Krajewski, W. F. Peck, J. H. Marshall, and D. H. Rapkine, Appl. Phys. Lett., vol 64, pp.2071 (1994).
□5□ T. Minami, H. Sonohara, T. Kakumu, and S. Takata, Jpn. J. Appl. Phys., Part 2 , vol 34, L971 (1995).
□6□ Von H, Kasper Z. Anorg Allg Chemie, vol 349, pp.113 (1967).
□7□ T. Minami, T. Kakumu, S. Tanaka, J. Vac. Sci. Technol. A, vol 14, pp.1704 (1996).
□8□ 顧鴻壽，光電有機電激發光顯示器技術及應用，新文京開發出版有限公司，pp.133-140, 2002.
□9□ Tadatsugu Minami, J. Vac. Sci. Technol. A, vol 17, pp.1765 (1999).
□10□ T. Minami, T. Kakumu, Y. Takeda, and S. Takata, Thin Solid Films 317, pp.326, (1998).
□11□ Julia M. Phillips, R.J. Cava, G. A. Thomas, S. A. Carter, J. Kwo, T. Siegrist, J. J. Krajewski, J. H. Marshall, W. F. Peck, Jr., and D.H. Rapkine, Appl. Phys. Lett. 67, pp.2246 (1995).
□12□ T. Minami, H. Kumagai, T. Kakumu, S. Takata, and M.lshii, J. Vac. Sci.Technol.,A 15, pp.1069 (1997).
□13□ 陳昱文，盧信沖，□銦鋅氧化物(IZO)透明導電膜持磁控濺鍍法製備與鑑定之探討，長庚大學化工與材料工程研究所碩士論文，2000.
□14□ 李玉華，□透明導電膜及其應用□，□科儀新知，第十二卷，第一期□，pp.94-101，1990。
□15□ Martinez, M A. Herrero, and J. Gutierrez, M T , Solar Energy Materials & Solar Cells., v 45 n1 Jan 1, pp75-86 (1997).
□16□ □次世代ディスプレイに向けだ電極材料の提案"，出光興產株式會社。
[17] Mitsuo fukuda, “Optical semiconductor devices”, Wiley Series in Microwave and Optical Engineering.
[18] Kim, Kun Ho, Park. Ki Cheol, Ma, Dae Young, J. Appl. Phys., v81 n12 Jun 15, pp7764-7772 (1997).
[19] Y.C. Lin, S.J. Chang, Y.K. Su, T.Y. Tasi, C.S. hang, S.C. Shei, C.W. Kuo, S.C. Chen, Solid State Electron., vol 47, pp.849-853, 2003.
[20] R.H. Horng, D. S. Wuu, Y.C. Lien, W.H Lan, Appl. Phys. Lett., vol 79, pp2925-2927, 2002.
[21] D.W. Kim, Y. J. Sung, J.W. Park, G. Y. Yeom, Thin Solid Films 398-399, pp87-92, 2001.
[22] G. K. Reeves, Solid-State Electron. 23, 487-490, May 1980
[23] A. J. Willis and A. P Botha, Thin Solid Films 146, 15-20, Jan. 1987
[24] H. Murmann and D. Widmann, Solid-State Electron. 12, 879-886, Dec. 1969