本論文利用高頻電容及阻抗頻譜來探討氧化鎂系統磁性穿隧接面之磁電傳輸行為，其目的在同時討論絕緣層紋理和界面品質對穿隧磁阻變化之影響。摻雜4Å金屬鎂於下電極層鈷鐵合金及絕緣層氧化鎂的磁性穿隧接面樣品有助於提升穿隧磁阻率(0.76%到4%)，利用高頻電容及阻抗頻譜討論絕緣層紋理氧化鎂和絕緣層及電極層間界面的介電貢獻，並且利用X-ray反射率和高解析電子顯微鏡來檢測絕緣層及界面問題。
摻雜4Å金屬鎂於下電極層鈷鐵合金及絕緣層氧化鎂之間有助提升絕緣層氧化鎂遲豫頻率和減少界面缺陷，由X-ray反射率和高解析電子顯微鏡也可以佐證高頻界面部分結果。故摻雜4Å金屬鎂於氧化鎂系統磁性穿隧接面中絕緣層和下電極層之間可有效提升磁阻率，主要原因是來自於改善氧化鎂絕緣層和界面條件。

In this thesis, we have systematically investigated the electrical- and magneto-transport properties in MgO-based magnetic tunnel junctions (MTJs), due to Mg doping at the bottom interface, by complex- capacitance (CC) and –impedance (CI) technique. We focus on the sample with/without inserting 4Å Mg discontinuous layer between the bottom CoFe electrode layer and the MgO barrier layer. The tunnel magnetoresistance (TMR) of MTJs with Mg doping shows a apparent increase to ~4%, compared to only 0.76% TMR ratio of MTJs without Mg doping. The corresponding CI and CC spectra with/without Mg doping MTJs are also measured and analyzed by the equivalent circuit model. The analysis indicates inserting 4Å Mg discontinuous layer between the bottom CoFe layer and the MgO barrier layer not only can improve barrier quality, but also decrease interfacial defects. Furthermore, we also use the X-ray reflectivity and high-resolution transmission electron microscopy to confirm the improvement of barrier texture and interfacial conditions. Therefore, we conclude the enhancement of TMR ratio due to 4 Å Mg doping could be related to the improvement of the bottom interfacial smoothness as well as the increase of textured MgO.

第一章
[1] S. Maekawa and U. G¨afvert, IEEE Trans. Magn. 18, 707 (1982).
[2] T, Miyazaki and N. J. Tezuka, J. Magn. Magn. Mater. 139, L231 (1995).
[3] J. S. Moodera, L. R. Kinder, T. M. Wong and R. Meservey, Phys. Rev. Lett. 74, 3273 (1995).
[4] M. Tsunoda, K. Nishikawa, S. Ogata, and M. Takahashi, Appl. Phys. Lett. 80, 3135 (2002)
[5] D. Wang, C. Nordman, J. M. Daughton, Z. Qian, and J. Fink, IEEE Trans. Magn. 40, 2269 (2004).
[6] J. Mathon and A. Umerski, Phys. Rev. B 63, 220403, (2001).
[7] S. S. P. Parkin, C. Kaiser, A. Panchula, P. M. Rice, B. Hughes, M. Samant and S. H. Yang, Nat. Mater. 3, 862 (2004).
[8] K. Tsunekawa, D. D. Djayaprawira, M. Nagai, H. Maehara, S. Yamagata, N. Watanabe, S. Yuasa, Y. Suzuki, and K. Ando, Appl. Phys. Lett. 87, 072503 (2005).
[9] J. Hayakawa, S. Ikeda, Y. M. Lee, F. Matsukura, and H. Ohno, Appl. Phys. Lett. 89, 232510 (2006).
[10] A. C. C. Yu, R. Doole, A. Petford-Long and T. Miyazaki, Jpn. J. Appl. Phys. 40 5058 (2001).
[11] S. Yuasa, T. Nagahama, A. Fukushima, Y. Suzuki, K. Ando, Nat. Mater., 3, 868 (2004).
[12] S. Yuasa, A. Fukushima, H. Kubota, Y. Suzuki, and K. Ando, Appl. Phys. Lett. 89, 042505 (2006).
[13] T. Dimopoulos, G. Gieres, J. Wecker, N. Wiese, Y. Luo and K. Samwer, J. Appl. Phys. 98, 073705 (2005).
[14]D. D. Djayaprawira, K. Tsunekawa, M. Nagai, H. Maehara, S. Yamagata, N. Watanabe, S. Yuasa, Y. Suzuki, and K. Ando, Appl. Phys. Lett. 86, 092502 (2005).
[15] K. Tsunekawa, D. D. Djayaprawira, S. Yuasa, M. Nagai1, H. Maehara, S. Yamagata, E. Okada, N. Watanabe, Y. Suzuki and K. Ando,IEEE Trans. Magn.42,2(2006)
[16] G. X. Miao, K. B. Chetry, A. Gupta, W. H. Butler, K. Tsunekawa, D. Djayaprawira and G. Xiao, J. Appl. Phys. 99, 08T305(2006)
[17] J. C. Read, P. G. Mather and R. A. Buhrman, Appl. Phys. Lett. 90, 132503(2007)
[18] J. C. A. Huang and C. Y. Hsu, Appl. Phys. Lett. 85, 24(2004)
[19] J. C. A. Huang and C. Y. Hsu, J. Appl. Phys. 98,064901(2005)

第二章
[1] M.N. Bibich, J.M.,A.Fert, F.Nugyen van Dau, F.Petroff, P.Eienne, G.Creuzt, A. Friendeich, and J.Chzels, Pys, Rev. Lett. Vol.61, 2472(1988)
[2] R. Von. Helmot, J. Wecker, B. Holzapfel, L. Schultz and K. Samwer,Phys. Rev. Lett. 71, 2331 (1993).
[3] S. Jin, T. H. Tiefel, M. McCormack, R. A. Fastnacht, R. Ramesh and L. H. Chen, Science, 264, 413 (1994)
[4] S. Jin, T. H. Tiefel, M. McCormack, H. O. M. Bryan, L. H. Chen and R. Ramesh, App. Phys. Lett. 67, 577 (1995).
[5] M. Jullière, Phys. Lett. A 54 (1975) 225; M. Jullière, Thesis of Rennes University, No. B368/217, Rennes, (1975)
[6]Chelkowski, A.,”Dielectric Physics”, Polish Scientific Publishers, New York, (1980)

第三章
[1] 顏君乘、黃榮俊, 高真空退火處理對氧化釩薄膜磁性與結構的研究,成大物理碩士論文(2004)。
[2] http://www.ncku.edu.tw/%7Efacility/facility/index.htm,成功大學貴重儀器中心(2007)。
[3] http://140.116.176.21/www/technique/SOP_nano/SOP-(TEM-2010).doc,成功大學微奈米中心(2007)。