本研究中，我們利用射頻磁控共濺鍍系統成長n型之ZnCoO、ZnCoO: Al 與p型之ZnCoO:N、ZnCoO:(Al,N)薄膜，並研究其結構、電性、光學以及磁性質，以釐清氧化鋅為基底之稀磁半導體的室溫鐵磁性來源。
全部的實驗包含五個部分，第一個部分為Zn1-xCoxO薄膜的製作與物理性質之研究。Zn1-xCoxO薄膜是以射頻磁控濺鍍系統於氬氣的氛圍下製做的。根據結構與光學之量測結果顯示，Co2+ 離子成功地取代了ZnO中Zn2+ 離子的位置，證實射頻磁控濺鍍系統可以有效地成長以ZnO為基底的稀磁性半導體。由磁性與電性量測結果顯示，樣品皆呈現順磁性且載子濃度為10^19 cm^-3 之n型半導體。
在第二部分中，我們為了提高ZnCoO之n型載子濃度，製作一系列不同Al濃度之ZnCoO:Al薄膜。發現Al的摻雜確實可提升ZnCoO之載子濃度，但Al對ZnCoO之溶解度極限大約6 at.%。此外，僅高載子濃度之ZnCoO:Al具有室溫鐵磁性。
在第三部分中，我們製作ZnCoO與ZnCoO:N薄膜，並比較其物理特性。ZnCoO薄膜是以純氬氣為濺鍍氣體，而ZnCO:N則是分別以Ar與N2混合氣體(氣體流量比為15:5 sccm)以及純N2兩種不同氣體為濺鍍氣體製作的。實驗結果顯示，無氮摻雜之ZnCoO樣品呈現n型之電性。氮摻雜的摻雜會使樣品之電性變差，並且以純氮氣為濺度氣體製作之ZnCoO:N樣品甚至出現了p型之電性。無N摻雜之ZnCoO的磁性為順磁，而隨著N摻雜的增加，樣品則出現了超順磁以及鐵磁與順磁之混合行為。
在第四部分中，為了提高ZnCoO之電洞載子濃度，我們使用Al-N共摻雜的方法製作p型的ZnCoO:(Al, N)薄膜，並與n型的ZnCoO:Al比較其物理特性。實驗結果顯示，ZnCoO:Al與ZnCoO:(Al, N)薄膜之載子濃度分別為5.34×10^20 cm^-3與5.27x10^13 cm^-3，且兩者均具有室溫鐵磁性，但僅ZnCoO:Al出現明顯的異常霍爾效應。
在第五部分中，我們試著以N2O為濺鍍氣體製作p型之ZnCoO:N稀磁半導體。由於載子的補償效應，使得樣品的電阻率太大，而無法判斷其電性與量出載子濃度之大小。然而，根據結構與光學之量測結果，我們依然可以確定Co2+與N3-離子均成功地取代了Zn2+與O2-離子的位置。至於磁性方面，僅有Co濃度較低之樣品具有室溫鐵磁性，而濃度較高者則呈現順磁性。因此，我們認為其室溫鐵磁機制適合以BMP模型解釋之，且其磁性質與ZnCoO中Co原子的濃度有密切之關係。
最後，我們歸納所有實驗結果，認為ZnCoO的磁性機制可來自兩種不同的鐵磁機制。束縛磁極子與載子引致機制分別適用於絕緣與導電之ZnCoO薄膜。

In this study, we grew n-type ZnCoO, ZnCoO:Al, and p-type ZnCoO: N, ZnCoO:(Al, N) thin films by using rf magnetron co-sputtering system, and investigated the structural, electrical, optical and magnetic properties to clarify the origin of room temperature ferromagnetism (RTFM) of ZnO-based diluted magnetic semiconductor.
Five parts are included in this experiment. The first part is the fabrication of Zn1-xCoxO thin films and investigations of the physical properties. The Zn1-xCoxO thin films were fabricated in Ar atmosphere by rf magnetron co-sputtering system. According to the results of the structural and optical measurements, the Co2+ ions successfully substituted Zn2+ ions sites of ZnO, proving that rf magnetron co-sputtering system can effectively fabricate ZnO-based diluted magnetic semiconductors. The results of magnetic and electrical measurements respectively present paramagnetism and n-type conduction with electron concentration of 10^19 cm^-3.
In the second part, in order to raise the n-type carrier concentration of ZnCoO, a series of ZnCoO:Al with different Al concentration were produced. The results of experiments show that Al-doping indeed promotes the carrier concentration but it has a solubility limit of 6 at.%. Besides, only the ZnCoO:Al with high carrier concentration has room temperature ferromagnetism.
In the third part, we fabricated Co doped and (Co, N) co-doped ZnO thin films, and compared the physical properties of them. The sputtering gas of pure argon was used for the ZnCoO film; two other different gases (a mixture of Ar and N2 (gas flow-ratio is 15:5 sccm) and a pure N2) were used for ZnCoO:N films. Without N-doping, the films showed n-type electrical conduction. Upon N-doping, the films became poorly conductive and even exhibited p-type conduction for pure N2 sputtering-gas. Paramagnetism was observed in the film with no N-doping (ZnCoO), but superparamagnetism and then a mixture of ferromagnetism plus paramagnetism were observed with increasing N-doping.
In the fourth part, in order to raise the hole-concentration of ZnCoO, we used the Al-N method to fabricate p-type ZnCoO:(Al, N) thin films, and compared the physical properties with the n-type ZnCoO:Al thin films. The results show that the carrier concentrations of ZnCoO:Al and ZnCoO:(Al, N) are 5.34×10^20 cm^-3 and 5.27×10^13 cm^-3 respectively. Both films possess RTFM, but only the ZnCoO:Al exhibits anomalous Hall-effect signals.
In the fifth part, we tried to do p-type Zn1-xCoxNyO1-y diluted magnetic semiconductor by using N2O for sputtering gas. Due to the charge compensation, the resistances of samples were too large to determine the conduction type and obtain the carrier concentration. However, we still can confirm that Co2+ and N3- ions successfully substitute Zn2+ and O2- sites for the films by structural and optical measurements. In the case of magnetic property, only the film with lower atomic concentration of cobalt possesses RTFM, and the other films with higher Co concentration present paramagnetism. We consider the mechanism of RTFM is suitable to be explained by BMP model, and the ferromagnetism is sensitive to the cobalt content of ZnCoO films.
Finally, we summarize all the results of experiments and suggest that there are two distinct ferromagnetic mechanisms that can give rise to ferromagnetism in ZnO:Co. The magnetic polarons and carrier-mediated exchange mechanisms are suitable in insulating and conductive ZnCoO films respectively.

Chapter 1
[1] S. A. Wolf et al., Science 294, 1488-1495 (2001).
[2]黃榮俊、許華書，物理雙月刊，26期4卷2004年8月，p.599.
[3]胡裕民，物理雙月刊，26期4卷2004年8月，p.587.
[4]盧志權, 工業材料雜誌, 169, 117 (2001).
[5] S. J. Pearton, C. R. Abernathy, D. P. Norton, A. F. Hebard, Y. D. Park, L. A. Boatner, J. D. Budai, Mat. Science and Eng., R40, 137 (2003).
[6] H. Ohno, Science 281, 951 (1998).
[7] H. Munekata, H. Ohno, S. von Molnar, A, Segmuller, L. L. Chang, and L. Esaki, Phys. Rev. Lett. 63, 1849 (1989).
[8] S. Koshihara, A. Oiwa, M. Hirasawa, S. Katsumoto, Y. Iye, C. Urano, H. Takagi, and H. Munekata, Phys. Rev. Lett. 78, 4617 (1997).
[9] T. Dietl, H. Ohno, F. Matsukura, J. Cibert, D. Ferrand, Science 287, 1019 (2000).
[10] S. Sonoda, S. Shimizu, T. Sasaki, Y. Yamamoto, H. Hori, J. Cryst. Growth 237–239, 1358 (2002).
[11] K. Sato and H. Katayama-Yoshida, Jpn. J. Appl. Phys., Part 2 39, L555 (2000).
[12] K. Sato and H. Katayama-Yoshida, Physica B 308-310, 904 (2001).
[13] K. Sato and H. Katayama-Yoshida, Semicond. Sci. Technol. 17, 367 (2002).
[14] K. Ueda, H. Tabata, and T. Kawai, Appl. Phys. Lett. 79, 988 (2001).
[15] J. M. D. Coey, M. Venkatesan, and C. B. Fitzgerald, Nat. Mater. 4, 173 (2005).
[16] A. J. Behan, A. Mokhtari, H. J. Blythe, D. Score, X. H. Xu, J. R. Neal, A. M. Fox, and G. A. Gehring, Phys. Rev. Lett. 100, 047206 (2008).
Chapter 2
[1] T. Dietl, H. Ohno, F. Matsukura, J. Cibert, D. Ferrand, Science 287, 1019 (2000).
[2] C. Zener, Phys. Rev. 82, 403 (1951).
[3] Y. Fukuma, F. Odawara, H. Asada, and T. Koyanagi Phys. Rev. B 78, 104417 (2008).
[4] J. M. D. Coey, M. Venkatesan, and C. B. Fitzgerald, Nat. Mater. 4, 173 (2005).
[5] W. F. L. Brown, J. Appl. Phys. 30, 130S (1959).
[6] W. T. Coffey, Yu. P. Kalmykov, and J. T. Waldron, The Langevin Equation (World Scientific, Singapore, 1996).
[7] Weil, Gruner, and Deschamps, Comp. Rend. 244, 2143 (1957).
[8] A. Knappwost, Z. Elektrochem. 61, 1328 (1957).
[9] R. Hahn and E. Kneller, Z. Metallk. 49, 426 (1958).
[10] A. E. Berkowitz and P. J. Flanders, J. Appl. Phys. 30, 111S (1959).
[11] Ü. Özgür, et al., J. Appl. Phys. 98, 041301 (2005).
[12] Y. Liu, C. R. Goria, S. Liang, N. Emanetoglu, Y. Lu, H. Shen and M. Wraback, J. Electron. Mater. 29, 69 (2000).
[13] Y. Chen, D. M. Bagnall, H.-J. Koh, K.-T. Park, K. Hiraga, Z.-Q. Zhu, and T. Yao, J. Appl. Phys. 84, 3912 (1998).
[14] R. D. Vispute et al., Appl. Phys. Lett. 73, 348 (1998).
[15] M. Kasuga and S. Ogawa, Jpn. J. Appl. Phys., Part 1 22, 794 (1983).
[16] J. G. E. Gardeniers, et al., J. Appl. Phys. 83,7844 (1998).
[17] T. Minami,H. Sato, H. Nanto, and Takata , Jpn. J. Appl. Phys., Part 2 24, L781 (1985).
[18] W. Walukiewicz, Phys. Rev. B 50, 5221 (1994).
[19] M. Joseph, H. Tabata, and T. Kawai, Jpn. J. Appl. Phys., Part 2 38, L1205 (1999).
[20] J. K. Furdyna, et al., J. Appl. Phys. 64, R29 (1988).
[21] H. Ohno, T. Dietl, Phys. Rev. Lett. 68, 2664 (1992).
[22] H. Ohno, A. Shen, F. Matsukura, A. Oiwa, A. Endo, S. Katsumoto, and Y. Iye, Appl. Phys. Lett. 69, 363 (1996).
[23] K. Sato, and H. Katayama-Yoshida, Jpn. J. Appl. Phys. 40, L334-L336 (2001).
[24] K. Ueda, H. Tabata, and T. Kawai, Appl. Phys. Lett. 79, 988 (2001).
[25] J. H. Kim, H. Kim, D. Kim, Y. E. Ihm, and W. K. Choo, J. Appl. Phys. 92, 6066 (2002).
[26] Z. Yin, N. Chen, C. Chai, and F. Yang, J. Appl. Phys. 96, 5093 (2004).
[27] A. J. Behan, A. Mokhtari, H. J. Blythe, D. Score, X-H. Xu, J. R. Neal, A. M. Fox, and G. A. Gehring, Phy. Rev. Lett. 100, 047206 (2008).
Chapter 3
[1] M Joshi, et al., Indian Journal of Fibre & Textile Research 33, 304-317 (2008).
[2] J. Tauc, “Amorphous and Liquid Semiconductors”, Plenum, London, (1974).
[3] E. A. David, and N. F. Mott, Philosophical Magazine, 22, 903 (1970).
[4] S.R. Reddy et al., Thin Solid Films 143, 113 (1986).
Chapter 4
4-1
[1] K. Ueda, H. Tabata, and T. Kawai, Appl. Phys. Lett. 79, 988 (2001).
[2] J. M. D. Coey, M. Venkatesan, and C. B. Fitzgerald, Nat. Mater. 4, 173 (2005).
[3] A. J. Behan, A. Mokhtari, H. J. Blythe, D. Score, X. H. Xu, J. R. Neal, A. M. Fox, and G. A. Gehring, Phys. Rev. Lett. 100, 047206 (2008).
[4] S. Ye, V. Ney, T. Kammermeier, K. Ollefs, S. Zhou, H. Schmidt, and A. Ney, J. Phys.: Cof. Ser. 200, 05234 (2010).
[5] Y. Z. Yoo, T. Fukumura, Z. Jin, K. Hasegawa, M. Kawasaki, P. Ahmet, T. Chikyow, and H. Koinuma , J. Appl. Phys. 90, 4246, (2001).
[6] L. Daheron, R. Dedryvere, H. Martinez, M. Menetrier, C. Denage, C. Delmas, and D. Gonbeau, Chem. Mater. 20, 583, (2008).
[7] X. J. Liu, C. Song, F. Zeng, and F. Pan, Thin Solid Films 516, 8757, 2008.
4-2
[1] H. Ohno, Science 281, 951 (1988.)
[2] T. Zhu, W. S. Zhan, W. G. Wang and J. Q. Xiao, Appl. Phys. Lett. 89,022508 (2006).
[3] N. Khare, M. J. Kappers, M. Wei, M. G. Blamire and J. L. MacManus-Driscoll J L, Adv. Mater. 18, 1449 (2006).
[4] H. T. Lin, T. S. Chin, J. C. Shih, et al., Appl. Phys. Lett. 85, 621 (2004)
[5] X. C. Liu, E. W. Shi, Z. Z. Chen, et al., Appl. Phys. Lett. 88, 252503 (2006).
[6] Y. Z. Yoo, T. Fukumura, Z. Jin, K. Hasegawa, M. Kawasaki, P. Ahmet, T. Chikyow, and H. Koinuma, J. Appl. Phys. 90, 4246 (2001).
[7] J. Alaria, H. Bieber ,S. Colis , et al., Appl. Phys. Lett. 88, 112503 (2006).
4-3
[1] K. Sato and H. K-Yoshida, Jpn. J. Appl. Phys. 40, L334 (2001).
[2] X.-L. Li, Z.-Y. Quan, X.-H. Xu, H.-S. Wu, and G. A. Gehring, IEEE Trans. Magn. 44, 2648 (2008).
[3] S. G. Yang, A. B. Pakhomov, S. T. Hung, and C. Y.Wong, IEEE Trans. Magn. 38, 2877 (2002).
[4] H.-J. Lee, C. H. Park, S.-Y. Jeong, K.-J. Yee, C. R. Cho, M.-H. Jung,
and D. J. Chadi, Appl. Phys. Lett. 88, 062504 (2006).
[5] H.-T. Lin, T.-S. Chin, J.-C. Shih, S.-H. Lin, T.-M. Hong, R.-T. Huang, F.-R. Chen, and J.-J. Kai, Appl. Phys. Lett. 85, 621 (2004).
[6] M. H. F. Sluiter, Y. Kawazoe, P. Sharma, A. Inoue, A. R. Raju, C. Rout, and U. V. Waghmare, Phys. Rev. Lett. 94, 187204-1–187204-4, (2005).
[7] P. Cao, D. X. Zhao, J. Y. Zhang, D. Z. Shen, Y. M. Lu, X. W. Fan, and X. H. Wang, Phys. B, vol. 392, 255 (2007).
[8] J. Lu, Z. Ye, L. Wang, J. Huang, and B. Zhao, Mater. Sci. Semicond. Processing 5, 491 (2003).
[9] M. Futsuhara, K. Yoshioka, and O. Takai, Thin Solid Films 317, 322 (1998).
[10] X. J. Liu, C. Song, F. Zeng, and F. Pan, Thin Solid Films 516, 8757 (2008).
[11] Y. Z. Yoo, T. Fukumura, Z. Jin, K. Hasegawa,M. Kawasaki, P. Ahmet, T. Chikyow, and H. Koinuma, J. Appl. Phys 90, 4246 (2001).
[12] L. Daheron, R. Dedryvere, H. Martinez, M. Menetrier, C. Denage, C. Delmas, and D. Gonbeau, Chem. Mater. 20, 583 (2008)
[13] J. M. Bian, X. M. Li, C. Y. Chang, W. D. Yu, and X. D. Gao, Appl. Phys. Lett. 85, 4070 (2004).
[14] Y. Lee and T. Han, Jpn. J. Appl. Phys. 43, 7477 (2004).
[15] J. M. D. Coey, M. Venkatesan, and C. B. Fitzgerald, Nat. Mater. 4, 173 (2005).
[16] T. Dietl, H. Ohno, F. Matsukura, J. Cibert, and D. Ferrand, Science 287, 1019 (2000).
[17] K. R. Kittilstved and D. R. Gamelin, J. Amer. Chem. Soc. 127, 5292 (2005).
4-4
[1] K.R. Kittilstved, N.S. Norberg, D.R. Gamelin, Phys. Rev. Lett. 94, 147209 (2005).
[2] Q. Xu, L. Hartmann, H. Schmidt, H. Hochmuth, M. Lorenz, Y. Liu, J. Appl. Phys. 101, 063918 (2007).
[3] J.M.D. Coey, M. Venkatesan, C.B. Fitzgerald, Nat. Mater. 4, 173 (2005).
[4] K.R. Kittilstved, W.K. Liu, D.R. Gamelin, Nat. Mater. 5, 291 (2006).
[5] H.-T. Lin, T.-S. Chin, J.-C. Shih, S.-H. Lin, T.-M. Huang, F.-R. Chen, J.-J. Kai, Appl. Phys. Lett. 85, 621 (2004).
[6] M.H.F. Sluiter, Y. Kawazoe, P. Sharma, A. Inoue, A.R. Raju, C. Rout, U.V. Waghmare, Phys. Rev. Lett. 94, 187204 (2005).
[7] P. Cao, D.X. Zhao, J.Y. Zhang, D.Z. Shen, Y.M. Lu, Z.W. Fan, X.H. Wang, Physica B 392, 255 (2007).
[8] T. Yamamoto, H. Katayama-Yoshida, Jpn. J. Appl. Phys. 38, L166 (1999).
[9] L. Daheron, R. Dedryvere, H. Martinez, M. Menetrier, C. Denage, C. Delmas, D. Gonbeau, Chem. Mater. 20 (2008) 583.
[10] J.F. Moulder, W.F. Stickle, P.E. Sobol, K.D. Bomben, Handbook of X-ray photoelectron spectroscopy, in: J. Chastain, R.C. King Jr (Eds.), Physical Electronics, pp. 42–88 (1995).
[11] N.O. Korsunska, L.V. Borkovska, B.M. Bulakh, L.Yu. Khomenkova, V.I. Jushnirenko, I.V. Markevish, J. Lumin. 102-103, 733 (2003).
[12] S.A. Studenikin, N. Golego, M. Cocivera, J. Appl. Phys. 84, 2287 (1998).
[13] F.H. Leiter, H.R. Alves, N.G. Romanov, D.M. Hoffmann, B.K. Meyer, Physica B 340–342, 201 (2003).
[14] K. Thonke, Th. Gruber, N. Teofilov, R. Schonfelder, A. waag, R. Sauer, Physica B 308–310, 945 (2001).
[15] D.C. Look, D.C. Reynolds, C.W. Litton, R.L. Jones, D.B. Eason, G. Cantwell, Appl. Phys. Lett. 81, 1830 (2002).
[16] Y. Lee, J.C. Lee, C.W. Su, IEEE Trans. Magn. 46, 1565 (2010).
[17] Y.H. Lee, T.C. Han, J.C.A. Huang, J. Appl. Phys. 93, 8462 (2003).
[18] H. Ohno, J. Magn. Magn. Mater. 200, 110 (1999).
[19] H. Toyosaki, T. Fukumura, Y. Yamada, K. Nakajima, T. Chikyow, T. Hasegawa, H. Koinuma, M. Kawasaki, Nat. Mater. 3, 221 (2004).
[20] S.R. Shinde, S.B. Ogale, J.S. Higgins, H. Zheng, A.J. Millis, V.N. Kulkarni, R. Ramesh, R.L. Greene, T. Venkatesan, Phys. Rev. Lett. 92, 166601 (2004).
[21] Q. Zu, H. Schmidt, S. Zhou, K. Potzger, M. Helm, H. HOchmuth, M. Lorentz, A. Setzer, P. Esquinazi, C. Meinecke, M. Grundmann, Appl. Phys. Lett. 92, 082508 (2008).
[22] Z.H. Zhang, X. Wang, J.B. Xu, S. Muller, C. Ronning, Q. Li, Nat. Nanotechnol. 4, 523 (2009).
4-5
[1] H, Ohno, A. Shen, F. Matsukura, A.Oiwa, A.Endo, S. Katsumoto, and Y. Iye, Appl. Phys. Lett. 69, 363 (1996).
[2] K. Sato and H. K-Yoshida, Jpn. J. Appl. Phys. 40, L334 (2001).
[3] H.-T. Lin, T.-S. Chin, J.-C. Shih, S.-H. Lin, T.-M. Huang, F.-R. Chen, J.-J. Kai, Appl. Phys. Lett. 85, 621 (2004).
[4] M.H.F. Sluiter, Y. Kawazoe, P. Sharma, A. Inoue, A.R. Raju, C. Rout, U.V. Waghmare, Phys. Rev. Lett. 94, 187204 (2005).
[5] P. Cao, D.X. Zhao, J.Y. Zhang, D.Z. Shen, Y.M. Lu, Z.W. Fan, X.H. Wang, Physica B 392, 255 (2007).
[6] Y. Z. Yoo, T. Fukumura, Z. Jin, K. Hasegawa, M. Kawasaki, P. Ahmet, T. Chikyow, and H. Koinuma, J. Appl. Phys. 90, 4246 (2001).
[7] X. J. Liu, C. Song, F. Zeng, F. Pan, Thin Solid Films 516, 8757 (2008).
[8] Y. H. Lee and T. C. Han, and J. C. A. Huang, J. Appl. Phys. 93, 8462 (2004).
[9] J. M. D. Coey, M. Venkatesan, and C. B. Fitzgerald, Nat. Mater. 4, 173 (2005).