本研究是利用脈衝雷射沉積將稀磁性氧化物鈷摻雜氧化鋅(Zn1-x CoxO)薄膜應用在氮化鎵發光二極體上的光電特性研究，並且在外加磁場下探討其元件特性的變化。
在未覆蓋Zn1-x CoxO薄膜以及分別覆蓋摻雜濃度X=0.05與0.07(通入氧氣成長)於發光二極體負極(n-GaN)的元件在注入電流200 mA時其光輸出功率(順向導通電壓)分別為44.05 mW(6.12 V)、49.24 mW(6.86 V)、57.09 mW(6.3 V)，而計算後其功率轉換效率為3.60%、3.59%、4.53%，在覆蓋薄膜後X=0.07的樣品雖然順向導通電壓較高，但是其光輸出功率提升了29.6%使得效率較佳，而X=0.05的樣品順向導通電壓增加許多，因此功率轉換效率並未提升。而覆蓋在發光二極體的正極(ITO/p-GaN)上方的樣品中其光輸出功率(順向導通電壓)分別為52.76 mW(5.68 V)、61.37 mW(5.84 V)，其功率轉換效率為4.64%、5.25%，推測原因是由於覆蓋在ITO之上後光穿透率損失很少且導電膜的厚度變厚而得到較低的側向電阻有利電流傳導而得到較低的導通電壓因而得到較高的光輸出功率與功率轉換效率。
我們也發現外加磁場下在未通入氧氣下沉積鈷摻雜氧化鋅薄膜的氮化鎵發光二極體會有磁光增益的現象，其電流分佈會更均勻擴展開來，而光輸出功率會大幅提升。而在通入氧氣沉積鈷摻雜氧化鋅薄膜的發光二極體樣品中，沒有發現顯著的磁光效應。

In this study, we used pulsed laser deposition for the growth cobalt-doped zinc oxide (Zn1-x CoxO) thin film on top of the p-GaN and n-GaN of the light-emitting diodes (LEDs). The magnetic and electrical effects on the LEDs were systematically studied.
The output power (forward voltage) of the LEDs with Zn0.95Co0.05O film (LED-N1.) and Zn0.93Co0.07O film (LED-N2) on n-GaN were 49.24 mW (6.86 V), 57.09 mW (6.3 V), respectively, with injection current of 200mA, in marked contrast to the LED without ZnCoO film (LED-std) of 4.05mW (6.12V). The wall-plug efficiency (WPE) of the samples were 3.59% (LED-N1), 4.53% (LED-N2) and 3.60% (LED-std). Although the forward voltage of LED-N2 is slightly higher than the LED-std but the output power of the LED-II is about 29.6% larger than the LED-std, so the efficiency of LED-N2 is far better than LED-std. The forward voltage of LED-N1 is rather high, so that its efficiency is not much improved.
The output power (forward voltage) of the LEDs with Zn0.95Co0.05O film (LED-P1) and Zn0.93Co0.07O film (LED-P2) on ITO/p-GaN top devices were 52.76 mW (5.68 V), 61.37 mW (5.84 V), respectively. The corresponding WPE of the devices were 4.64% (LED-P1) and 5.25% (LED-P2). This improvement could be attributed to the fact that the ZnCoO/ITO composite transparent conducting layer (TCL) has better transparency compared to ITO TCL . The thick ZnCoO/ITO TCL with low lateral resistance would also act as the current-spreading layer leading to an enhancement of the LED light extraction.
In this work, we also found an interesting phenomenon. When we measure the characteristics in a magnetic field, the LED light intensity was much higher and more uniform distributed on chip surface for the ZnCoO (on ITO/p-GaN top LEDs) which were deposited without oxygen.

第一章
1. 黃榮俊, 許華書. (2007), 鈷:氧化鋅（Co:ZnO）稀磁性半導體室溫鐵磁性機制研究. 成大研發快訊 第一卷.
2. Ohno, Y., et al., Electrical spin injection in a ferromagnetic semiconductor heterostructure. Nature, 1999. 402(6763): p. 790-792.
3. 呂彥興, 氧化鋅鎵薄膜成長在氮化鎵發光二極體上之應用, 光電科學與工程研究所. 2007, 國立成功大學. p. 78.
4. Hsu, H.S., et al., Evidence of oxygen vacancy enhanced room-temperature ferromagnetism in Co-doped ZnO. Applied Physics Letters, 2006. 88(24).
5. Lu, Z.L., et al., The origins of ferromagnetism in Co-doped ZnO single crystalline films: From bound magnetic polaron to free carrier-mediated exchange interaction. Applied Physics Letters, 2009. 95(10).
6. Lu, Z.L., et al., Tunable magnetic and transport properties of single crystalline (Co, Ga)-codoped ZnO films. Applied Physics Letters, 2009. 95(6).
7. Lu, Z.L., et al., Carrier-mediated ferromagnetism in single crystalline (Co, Ga)-codoped ZnO films. Applied Physics Letters, 2009. 94(15).
8. Hsu, H.S., et al., Room temperature anomalous Hall effect in Co doped ZnO thin films in the semiconductor regime. Applied Physics Letters, 2008. 93(14).
9. Tsukazaki, A., et al., Repeated temperature modulation epitaxy for p-type doping and light-emitting diode based on ZnO. Nature Materials, 2004. 4(1): p. 42-46.
10. Nakahara, K., et al., Nitrogen doped MgxZn1-xO/ZnO single heterostructure ultraviolet light-emitting diodes on ZnO substrates. Applied Physics Letters, 2010. 97(1): p. 013501-013501-3.
11. Chen, L.C., C.H. Tien, and C.S. Mu, Effects of spin-polarized injection and photo-ionization of MnZnO film on GaN-based light-emitting diodes. Optics Express, 2010. 18(3): p. 2302-2308.
12. 穆劍昇, 稀磁性半導體摻錳氧化鋅薄膜沉積於氮化鎵發光二極體之自旋注入特性與磁光倍增效應之研究與探討, 光電工程系研究所. 2010, 國立台北科技大學. p. 83.
13. Chen, P.H., et al., GaN-Based LEDs With AZO:Y Upper Contact. Ieee Transactions on Electron Devices, 2010. 57(1): p. 134-139.
14. Kuo, C.H., et al., Low operation voltage of nitride-based LEDs with Al-doped ZnO transparent contact layer. Electrochemical and Solid State Letters, 2008. 11(9): p. H269-H271.
15. Tu, S.H., et al., InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer. Applied Physics Letters, 2010. 96(13).
16. Sheu, J.K., et al., Ga-Doped ZnO Transparent Conductive Oxide Films Applied to GaN-Based Light-Emitting Diodes for improving Light Extraction Efficiency. Ieee Journal of Quantum Electronics, 2008. 44(11-12): p. 1211-1218.

第二章
17. 羅仁華, 後退火處理對鎵、鈷共摻雜氧化鋅磁電性之研究, 物理學系碩博士班. 2010, 國立成功大學. p. 89.
18. 汪建榮, 添加鈦或鈷對ZnO薄膜之影響, 材料科學及工程學系碩博士班. 2005, 國立成功大學. p. 123.
19. Powell, R.A., W.E. Spicer, and McMenami.Jc, PHOTOEMISSION STUDIES OF WURTZITE ZINC OXIDE. Physical Review B, 1972. 6(8): p. 3056-&.
20. Eckelt, P., O. Madelung, and J. Treusch, BAND STRUCTURE OF CUBIC ZNS (KORRINGA-KOHN-ROSTOKER METHOD). Physical Review Letters, 1967. 18(16): p. 656-&.
21. 許庭維, 氧化鋅摻雜鈷在低載子濃度下磁性、電性及光學性質研究, 物理學系碩博士班. 2011, 國立成功大學. p. 94.
22. 周廷璁, 鈷-氧化鋅奈米複合材料之高溫退火磁阻效應, 物理學系碩博士班. 2008, 國立成功大學. p. 127.
23. 陳隆建, 發光二極體之原理與製程: 全華圖書股份有限公司.
24. Schubert, E.F. Chapter 08: Design of current flow. Available from: www.lightemittingdiodes.org.

第三章
25. 羅吉宗, ed. 薄膜科技與應用(修訂二版). 修訂二版 . 2009.
26. 朱英豪, Ba(Mg1/3Ta2/3)O3緩衝層利用於低溫成長Pb(Zr1-xTix)O3薄膜之研究, 材料科學工程學系. 2004, 國立清華大學. p. 288.
27. 梁振偉, 雷射剝鍍法製作BMT緩衝層及其對PZT薄膜之影響研究, 材料科學工程學系. 2003, 國立清華大學. p. 84.
28. Pascal co., L.; Available from: http://www.pascal-co-ltd.co.jp/solutions/index.html.
29. P. K. Larsen and P. J. Dobson，Reflection High‐Energy
Electron Diffraction and Reflection Electron Imaging of
Surface， NATO ASI Series
30. 賴柜宏, 自組織奈米結構與氧化鋅表面現象之掃瞄式探針顯微術研究, 物理學系碩博士班. 2010, 國立成功大學. p. 173.
31. 邱淑琳, 磊晶單雙晶氧化鋅摻雜鈷稀磁性半導體鐵磁性來源之研究, 物理學系碩博士班. 2007, 國立成功大學. p. 96.

第四章
32. Li, S.Z., et al., Enhancement of ultraviolet electroluminescence based on n-ZnO/n-GaN isotype heterojunction with low threshold voltage. Applied Physics Letters, 2010. 96(20).
33. Sheu, J.K., et al., Characterization of Gallium-Doped Zinc Oxide Contact on n-Type Gallium Nitride Epitaxial Layers. Journal of the Electrochemical Society, 2009. 156(8): p. H679-H683.