We focus on the fabrication and resistive switching characteristics of ZnO films for nonvolatile memory applications. The unipolar and bipolar resistive switching characteristics of highly (002)-oriented and columnar-grained ZnO thin films were observed, respectively. Based on the pad size effect and temperature dependence of LRS, it can be realized that the LRS is related to the conduction though local metallic filament. The top electrode material dependence on resistive switching characteristics of ZnO was also investigated. The existence of oxygen ions in electrode and ZnO films would play an important role in resistance switching behavior.
The influence of crystalline constituent on electrical and resistive switching properties of TiO2 was investigated. The leakage current in HRS is sensitive to the crystal phase composition of the TiO2 matrix; however, the current flowed through the films in LRS is hardly affected. Besides, the improvement of resistive switching characteristics in TiO2 films with embedded Pt nanocrystals was also investigated.
So far, the resistive switching behaviors have investigated not only in ZnO thin films, but also in ZnO nanorods (NRs). The distinct geometry of ZnO NRs leads to an excellent nonvolatile behavior with a narrow dispersion of HRS/LRS ratio due to the formation of straight and extensible conducting filaments along the direction of each vertically aligned ZnO NR.

本研究成功開發氧化鋅基電阻式記憶體之製程與元件特性，分別開發出具有單極性與雙極性電阻轉換特性之製程，均具有良好的操作特性與非揮發記憶特性。我們針對雙極性電阻轉換特性進一步探討，由電阻值對電極面積相關性以及對量測溫度相依性，推測其工作機制為局部導電的燈絲理論。我們亦探討電極材料對於氧化鋅基電阻式記憶體之影響性，研究發現選用具儲存氧離子或易氧化之電極材料是一大重要關鍵，其中以鉻電極具有最佳操作穩定性。
本研究亦開發二氧化鈦基電阻式記憶體之製程與元件特性，利用磁控濺鍍法鍍膜氣氛調控二氧化鈦薄膜之結晶結構，探討其對於電阻轉換特性之影響性。結果發現高電阻值受薄膜結晶結構影響，但低電阻值卻保持定值不變，推測工作機制為燈絲理論。此外，我們在二氧化鈦薄膜中加入白金奈米粒子，以此創新的奈米複合結構開發出更優異之電阻轉換特性。研究結果發現鑲埋白金奈米粒子之元件，其具有更穩定的操作特性，對於元件的耐久性與記憶特性大為提升。
本研究亦利用水熱法生成垂直陣列之奈米線，成功開發氧化鋅奈米線電阻式記憶體。 研究發現由於導電燈絲容易沿著奈米線表面垂直生成，故此奈米結構具有更佳電阻轉換穩定性。

Chapter 1 Introduction 1
Chapter 2 Literature review 4
2-1 Semiconductor Memory 4
2-2 Emerging non-volatile memory 7
2-2-1 FeRAM (Ferroelectric RAM) 7
2-2-2 MRAM (Magnetoresistive RAM) 8
2-2-3 PRAM (Phase-change RAM) 10
2-2-4 RRAM (Resistance RAM) 11
2-3 RRAM materials 16
2-3-1 Binary metal oxide 16
2-3-2 Perovskite structure 19
2-3-3 Organic materials 21
2-4 Resistive switching mechanisms 23
2-4-1 Conducting filament model 24
2-4-2 Interface-type conducting path 27
2-4-3 Cell size dependence of LRS 28
Chapter 3 Influence of crystalline constituent on resistive switching properties of TiO2 memory films 30
3-1 Introduction 30
3-2 Experimental process 31
3-3 Materials analysis 33
3-4 Resistive switching characteristics 36
3-5 Conduction mechanism 41
3-6 Influence of crystalline constituent on resistive switching mechanism 43
3-7 Conclusions 44
Chapter 4 Unipolar resistive switching characteristics of ZnO thin films 45
4-1 Introduction 45
4-2 Experimental process 46
4-3 Material analysis 47
4-4 Unipolar resistive switching characteristics 52
4-4-1 Unipolar resistive switching mode 52
4-4-2 Conduction mechanism 57
4-4-3 Unipolar resistive switching mechanism 60
4-5 Diode-like resistive switching characteristics 61
4-6 Conclusions 67
Chapter 5 Bipolar resistive switching characteristics of ZnO thin films 68
5-1 Introduction 68
5-2 Experimental process 69
5-3 Polarity of bipolar resistive switching characteristics 72
5-4 Current compliance effect in bipolar resistive switching behavior 76
5-5 Conduction mechanism 82
5-6 Bipolar resistive switching mechanism 90
5-7 Conclusions 94
Chapter 6 Effect of top electrode material on resistive switching stability of ZnO films 95
6-1 Introduction 95
6-2 Experimental process 98
6-3 Resistive switching characteristics of TE/ZnO/Pt capacitor 101
6-4 The influence of electrode materials on resistive switching stability 110
6-5 The electrode-related resistive switching mechanism 114
6-6 Conclusions 120
Chapter 7 Improvement of resistive switching characteristics in TiO2 thin films with embedded Pt nanocrystals 121
7-1 Introduction 121
7-2 Experimental process 122
7-3 Materials analysis 125
7-4 Improvement of resistive switching characteristics 127
7-5 Conclusions 135
Chapter 8 Resistive switching behaviors of ZnO nanorod layers 136
8-1 Introduction 136
8-2 Experimental process 137
8-3 Microstructure of ZnO NRL 138
8-4 Resistive switching characteristics of ZnO NRL 140
8-5 Resistive switching mechanism of ZnO NRL 145
8-6 Conclusions 148
Chapter 9 Summary 149
Reference 151
Appendix 158
A-1 Resistive switching characteristics in Pr0.7Ca0.3MnO3 thin films on LaNiO3-electrodized Si substrate 158
A-2 Unipolar and bipolar resistive switching characteristics in epitaxial BiFeO3 films 168
Publications list 179

1. C. Muller, IEEE Computer Society Annual Symposium on VLSI, 2008, 3.
2. C. H. Chen, Master thesis, National Tsing Hua University, 2009.
3. A. Sawa, Materials Today, 11, 28 (2008).
4. F. Chen, New Non-volatile Memory Workshop, 2008.
5. G. Muller, N. Nagel, C. U. Pinnow, and T. Röhr, Solid-State Circuits Conference, 2003, 37.
6. G. Muller, T. Happ, M. Kund, G. Y. Lee, N. Nagel, R. Sezi, Tech. Dig. - Int. Electron Devices Meet. 2004, 567.
7. 葉林秀、李佳謀、徐明豐、吳德和, 物理雙月刊(廿六卷四期), 607 (2004).
8. W. Y. Chang, J. H. Liao, Y. S. Lo, and T. B. Wu, Appl. Phys. Lett. 94, 172107 (2009).
9. W. Y. Chang, Y. C. Lai, T. B. Wu, S. F. Wang, F. Chen, and M. J. Tsai, Appl. Phys. Lett. 92, 022110 (2008).
10. R. Waser, R. Dittmann, G. Staikov, and K. Szot, Adv. Mater. 21, 2632 (2009).
11. M. J. Lee, S. Seo, D. C. Kim, S. E. Ahn, D. H. Seo, I. K. Yoo, I. G. Baek, D. S. Kim, I. S. Byun, S. H. Kim, I. R. Hwang, J. S. Kim, S. H. Jeon, and B. H. Park, Adv. Mater. 19, 73 (2007).
12. I. G Baek, M. S. Lee., S. Seo, M. J. Lee, D. H. Seo, D. S. Suh, J. C. Park, S. O. Park, H. S. Kim, I. K. Yoo, U. I. Chung, and J. T. Moon, Tech. Dig. - Int. Electron Devices Meet. 2004, 587.
13. M. J. Lee, C. B. Lee, S. Kim, H. Yin, J. Park, S. E. Ahn, B. S. Kang, K. H. Kim, G. Stefanovich, I. Song, S. W. Kim, J. H. Lee, S. J. Chung, Y. H. Kim, C. S. Lee, J. B. Park, I. G. Baek, C. J. Kim, and Y. Park, Tech. Dig. - Int. Electron Devices Meet. 2008, 85.
14. Z. Wei, Y. Kanzawa, K. Arita, Y. Katoh, K. Kawai, S. Muraoka, S. Mitani, S. Fujii, K.Katayama, M. Iijima, T. Mikawa, T. Ninomiya, R. Miyanaga, Y. Kawashima, K. Tsuji, A. Himeno, T. Okada, R. Azuma, K. Shimakawa, H. Sugaya, T. Takagi, R. Yasuhara, K. Horiba, H. Kumigashira, and M. Oshima, Tech. Dig. - Int. Electron Devices Meet. 2008, 293.
15. H. Y. Lee, P. S. Chen, T. Y. Wu, Y. S. Chen, C. C. Wang, P. J. Tzeng, C. H. Lin, F. Chen, C. H. Lien, and M. J. Tsai, Tech. Dig. - Int. Electron Devices Meet. 2008, 297.
16. Y. H. Tseng, C.-E. Huang, C. H. Kuo, Y. D. Chih, C. J. Lin, Tech. Dig. - Int. Electron Devices Meet. 2009, 109.
17. T. W. Hickmott, J. Appl. Phys. 33, 2669 (1962).
18. J. G. Simmons, and R. R. Verderber, Proc. R. Soc. London, Ser. A 77, 301 (1967).
19. J. F. Gibbons, and W. E. Beadle, Solid-State Electron. 7, 785 (1964).
20. B. J. Choi, D. S. Jeong, S. K. Kim, C. Rohde, S. Choi, J. H. Oh, H. J. Kim, C. S. Hwang, K. Szot, R. Waser, B. Reichenberg, and S. Tiedke, J. Appl. Phys. 98, 033715 (2005).
21. K. M. Kim, B.J. Choi, and C. S. Hwang, Appl. Phys. Lett. 90, 242906 (2007).
22. W. Y. Chang, Y. T. Ho, T. C. Hsu, F. Chen, M. J. Tsai, and T. B. Wu, Electrochem. Solid-State Lett. 12, H135 (2009).
23. D. S. Lee, H. J. Choi, H. J. Sim, D. H. Choi, H. S. Hwang, M. J. Lee, S. A. Seo, and I. K. Yoo, IEEE Electron Device Lett. 26, 719 (2005)
24. X. Wu, P. Zhou, J. Li, L. Y. Chen, H. B. Lv, Y. Y. Lin, and T. A. Tang, Appl. Phys. Lett. 90, 183507 (2007).
25. C. Y. Lin, C. Y. Wu, C. Y. Wu, T. C. Lee, F. L. Yang, C. M. Hu, and T. Y. Tseng, IEEE Electron Device Lett. 28, 366 (2007)
26. C. Y. Lin, C. Y. Wu, C. Y. Wu, and T. Y. Tseng, J. Appl. Phys. 102, 094101 (2007).
27. S. Y. Wang, D. Y. Lee, T. Y. Tseng, and C. Y. Lin, Appl. Phys. Lett. 95, 112904 (2009).
28. H. Y. Lee, P. S. Chen, T. Y. Wu, Y. S. Chen, F. Chen, C. C. Wang, P. J. Tzeng, C. H. Lin, M. J. Tsai, and C. H Lien, IEEE Electron Device Lett. 30, 703 (2009)
29. N. Xu, L. F. Liu, X. Sun, X. Y. Liu, D. D. Han, Y. Wang, R. Q. Han, J. F. Kang, and B. Yu, Appl. Phys. Lett., 92, 232112 (2008).
30. A. Chen, S. Haddad, Y. C. Wu, T. N. Fang, Z. Lan, S. Avanzino, S. Pangrle, M. Buynoski, M. Rathor, W. Cai, N. Tripsas, C. Bill, M. V. Buskirk, and M. Taguchi, Tech. Dig. - Int. Electron Devices Meet. 2005, 746.
31. C. H. Ho, E. K. Lai, M. D. Lee, C. L. Pan, Y. D. Yao, K. Y. Hsieh, R. Liu, and C. Y. Lu, Dig. Tech. Pap. - Symp. VLSI Technol., 2007, 228.
32. S. Muraoka, K. Osano, Y. Kanzawa, S. Mitani, S. Fujii, K. Katayama, Y. Katoh, Z. Wei, T. Mikawa, K. Arita, Y. Kawashima, R. Azuma, K. Kawai, K. Shimakawa, A. Odagawa, and T. Takagi, Tech. Dig. - Int. Electron Devices Meet. 2007, 779.
33. K. Tsunoda, K. Kinoshita, H. Noshiro, Y. Yamazaki, T. Iizuka, Y. Ito, A. Takahashi, A. Okano, Y. Sato, T. Fukano, M. Aoki, and Y. Sugiyama, Tech. Dig. - Int. Electron Devices Meet. 2007, 767.
34. Y. Tokura and Y. Tomioka, J. Magn. Magn. Mater. 200, 1 (1999).
35. A. Asamitsu, Y. Tomioka, H. Kuwahara, and Y. Tokura, Nature (London) 388, 50 (1997).
36. S.Q. Liu, N. J. Wu, and A. Ignatiev, Appl. Phys. Lett. 76, 2749 (2000).
37. A. Beck, J. G. Bednorz, Ch. Gerber, C. Rossel, and D. Widmer, Appl. Phys. Lett. 77, 139 (2000).
38. K. Szot, W. Speier, R. Carius, U. Zastrow, and W. Beyer, Phys. Rev. Lett. 88, 075508 (2002).
39. K. Szot, W. Speier, G. Bihlmayer, and R. Waser, Nat. Mater. 5, 312 (2006).
40. M. Janousch, G. I. Meijer, U. Staub, B. Delley, S. F. Karg, and B. P. Andreasson, Adv. Mater. 19, 2232 (2007).
41. C. Rossel, G. I. Meijer, D. Bremaud, and D. Widmer, J. Appl. Phys. 90, 2892 (2001).
42. C. Y. Liu, P. H. Wu, A. Wang, W. Y. Jang, J. C. Young, K. Y. Chiu, and T. Y. Tseng, IEEE Electron Device Lett. 26, 351 (2005).
43. C. C. Lin, B. C. Tu, C. C. Lin, C. H. Lin, and T. Y. Tseng, IEEE Electron Device Lett. 27, 725 (2006).
44. C. Y. Lin, M. H. Lin, M. C. Wu, C. H. Lin, and T. Y. Tseng, IEEE Electron Device Lett. 29, 1108 (2008).
45. D. S. Shang, L. D. Chen, Q. Wang, W. Q. Zhang, Z. H. Wu, and X. M. Li, Appl. Phys. Lett. 89, 172102 (2006).
46. M. Hasan, R. Dong, H. J. Choi, D. S. Lee, D. J. Seong, M. B. Pyun, and H. S. Hwang, Appl. Phys. Lett. 92, 202102 (2008).
47. L. P. Ma, J. Liu, S. M. Pyo, and Y. Yang, Appl. Phys. Lett. 80, 362 (2002).
48. L. P. Ma, J. Liu, and Y. Yang, Appl. Phys. Lett. 80, 2997 (2002).
49. K. Kinoshita, T. Tamura, M. Aoki, Y. Sugiyama, H. Tanaka, Appl. Phys. Lett. 89, 103509 (2006).
50. Y. M. Kim and J. S. Lee, J. Appl. Phys. 104, 114115 (2008).
51. S. C. Chae, J. S. Lee, S. Kim, S. B. Lee, S. H. Chang, C. Liu, B. Kahng, H. Shin, D. W. Kim, C. U. Jung, S. Seo, M. J. Lee, and T. W. Noh, Adv. Mater. 20, 1154 (2008).
52. D. S. Lee, D. J. Seong, I. H. Jo, F. Xiang, R. Dong, S. K. Oh, and H. S. Hwang, Appl. Phys. Lett. 90, 122104 (2007).
53. J. Y. Son, and Y. H. Shin, Appl. Phys. Lett. 92, 222106 (2008).
54. U. Russo, D. Ielmini, C. Cagli, and A. L. Lacaita, IEEE Trans. Electron Devices, 56, 186 (2009).
55. U. Russo, D. Ielmini, C. Cagli, A. L. Lacaita, S. Spiga, C. Wiemer, M. Perego, and M. Fanciulli, Tech. Dig. - Int. Electron Devices Meet. 2007, 775.
56. K. Tsubouchi, I. Ohkubo, H. Kumigashira, M. Oshima, Y. Matsumoto, K. Itaka, T. Ohnishi, M. Lippmaa, and H. Koinuma, Adv. Mater. 19, 1711 (2007)
57. S. Tsui, A. Baikalov, J. Cmaidalka, Y. Y. Sun, Y. Q. Wang, Y. Y. Xue, C. W. Chu, L. Chen, A. J. Jacobson, Appl. Phys. Lett. 85, 317 (2004).
58. X. Chen, N. J. Wu, J. Strozier, A. Ignatiev, Appl. Phys. Lett. 87, 233506 (2005).
59. A. Sawa, T. Fujii, M. Kawawaki, and Y. Tokura, Appl. Phys. Lett. 85,4073 (2004).
60. M. J. Rozenberg, I. H. Inoue, and M. J. Sanchez, Phys. Rev. Lett. 92, 178302 (2004).
61. M. Hasan, R. Dong, H. J. Choi, D. S. Lee, D. J. Seong, M. B. Pyun, and H. S. Hwang, Appl. Phys. Lett. 92, 202102 (2008).
62. D. Chen, E. H. Jordan, M. Gell, Surf. Coat. Technol. 202, 6113 (2008)
63. Q. Wang, D. S. Shang, Z. H. Wu, L. D. Chen, and X. M. Li, Appl. Phys. A 86, 357 (2007).
64. M. A. Lampert and P. Mark, Current Injection in Solids (Academic Press, New York 1970)
65. K. M. Kim, B. J. Choi, D. S. Jeong, and C. S. Hwang, Appl. Phys. Lett. 89, 162912 (2006).
66. K. M. Kim, B. J. Choi, Y. C. Shin, S. Choi, and C. S. Hwang, Appl. Phys. Lett. 91, 012907 (2007).
67. D. C. Kim, S. Seo, S. E. Ahn, D. S. Suh, M. J. Lee, B. H. Park, I. K. Yoo, I. G. Baek, H. J. Kim, E. K. Yim, J. E. Lee, S. O. Park, H. S. Kim, U. I. Chung, J. T. Moon, and B. I. Ryu, Appl. Phys. Lett. 88, 202102 (2006).
68. H. Tang, K. Prasad, R. Sanjines, P. E. Schmid, and F. Levy, J. Appl. Phys. 75, 2042 (1994).
69. C. Jagadish and S. Pearton, Zinc oxide bulk, thin films and nanostructures (Elsevier, 2006)
70. M. Villafuerte, S. P. Heluani, G. Juárez, G. Simonelli, G. Braunstein, and S. Duhalde, Appl. Phys. Lett. 90, 052105 (2007).
71. J. R. Yeargan, H. L. Taylor, J. Appl. Phys., 39, 5600 (1968).
72. P. Yeh, Optical Waves in Layered Media (Wiley, New York, 1988).
73. W. Guan, S. Long, Q. Liu, M. Liu, and W. Wang, IEEE Electron Device Lett. 29, 434 (2008).
74. Q. Liu, C. Dou, Y. Wang, S. Long, W. Wang, M. Liu, M. Zhang, and J. Chen, Appl. Phys. Lett. 95, 023501 (2009).
75. P. S. Xu, Y. M. Sun, C. S. Shi, F. Q. Xu, and H. B. Pan, Nucl. Instrum. Methods Phys. Res. B 199, 286 (2003).
76. P. T. Hsieh, Y C. Chen, K. S. Kao, and C. M. Wang, Appl. Phys. A: Mater. Sci. Process. 90, 317 (2007).
77. H. Kohlstedt, A. Petraru, K. Szot, A. Rüdiger, P. Meuffels, H. Haselier, R. Waser, and V. Nagarajan, Appl. Phys. Lett. 92, 062907 (2008).
78. B. Gao, B. Sun, H. W. Zhang, L. F. Liu, X. Y. Liu, R. Q. Han J. F. Kang, and B. Yu, IEEE Electron Device Lett. 30, 1326 (2009).
79. S. Seo, M. J. Lee, D. C. Kim, S. E. Ahn, B. H. Park, Y. S. Kim, I. K. Yoo, I. S. Byun, I. R. Hwang, S. H. Kim, J. S. Kim, J. S. Choi, J. H. Lee, S. H. Jeon, S. H. Hong, and B. H. Park, Appl. Phys. Lett. 87, 263507 (2005).
80. W. Y. Yang and S. W. Rhee, Appl. Phys. Lett. 91, 232907 (2007).
81. R. Yang, X. M. Li, W. D. Yu, X. D. Gao, D. S. Shang, X. J. Liu, X. Cao, Q. Wang, and L. D. Chen1, Appl. Phys. Lett. 95, 072105 (2009).
82. X. M. Chen, G. H. Wu, and D. H. Bao, Appl. Phys. Lett. 93, 093501 (2008).
83. S. Kim, H. Moon, D. Gupta, S. Yoo, and Y. K. Choi, IEEE trans. Electron Device 56, 696 (2009).
84. J. W. Seo, J. W. Park, K. S. Lim, J. H. Yang, and S. J. Kang, Appl. Phys. Lett. 93, 223505 (2008).
85. J. W. Seo, J. W. Park, K. S. Lim, S. J. Kang, Y. H. Hong, J. H. Yang, L. Fang, G. Y. Sung, and H. K. Kim, Appl. Phys. Lett. 95, 133508 (2009).
86. D. C. Kim, M. J. Lee, S. E. Ahn, S. Seo, J. C. Park, I. K. Yoo, I. G. Baek, H. J. Kim, E. K. Yim, J. E. Lee, S. O. Park, H. S. Kim, U. I. Chung, J. T. Moon, and B. I. Ryu, Appl. Phys. Lett. 88, 232106 (2006).
87. L. F. Liu, J. F. Kang, N. Xu, X. Sun, C. Chen, B. Sun, Y. Wang, X. Y. Liu, X. Zhang, and R. Q. Han, Jpn. J. Appl. Phys. 47, 2701 (2008).
88. W. Guan, S. Long, R. Jia, and M. Liu, Appl. Phys. Lett. 91, 062111 (2007).
89. J. Y. Tseng, C. W. Cheng, S. Y. Wang, T. B. Wu, K. Y. Hsieh, and R. Liu, Appl. Phys. Lett. 85, 2595 (2004).
90. C. Rohde, B. J. Choi, D. S. Jeong, S. Choi, J. S. Zhao, and C. S. Hwang, Appl. Phys. Lett. 86, 262907 (2005).
91. C. W. Cheng, Y. C. Tseng, T. B. Wu, and L. J. Chou, J. Mater. Res. 19, 1043 (2004).
92. P. Yang, H. Yan, S. Mao, R. Russo, J. Johnson, R. Saykally, N. Morris, J. Pham, R. He, H. Choi, H. Adv. Func. Mater. 12, 323 (2002).
93. Z. L. Wang, Mater. Sci. Eng. R. 64, 33 (2009).
94. B. Yuhas, P. Yang, P. J. Am. Chem. Soc. 131, 3756 (2009).
95. W. Y. Chang, K. J. Cheng, J. M. Tsai, H. J. Chen, F. Chen, M. J. Tsai, T. B. Wu, Appl. Phys. Lett. 95, 042104 (2009).
96. S. M. Yu, B. Gao, H. B. Dai, B. Sun, L. F. Liu, X. Y. Liu, R. Q. Han, J. F. Kang, and B. Yu, Electrochem. Solid-State Lett. 13, H36 (2010).
97. S. I. Kim, J. H. Lee, Y. W. Chang, S. S. Hwang, K. H. Yoo, Appl. Phys. Lett. 93, 033503 (2008).
98. S. Baek, J. Song, S. Lim, Physica B 399, 101 (2007).
99. K. Vanheusden, W. L. Warren, C. H. Seager, D. R. Tallant, J. A. Voigt, and B. E. Gnade, J. Appl. Phys. 79, 7983 (1996).
100. L. E. Greene, M. Law, J. Goldberger, F. Kim, J. C. Johnson, Y. F. Zhang, R. J. Saykally, and P. D. Yang, Angew. Chem., Int. Ed. 42, 3031 (2003).