在本論文中，我們完成一些以氧化物來當作電阻轉換層製備而成的電阻式隨機存取記憶體元件，並且探討他們的特性。
首先，在室溫下，我們研究以Ti/TaO2/Pt為架構的電阻式隨機存取記憶體的製備方式與特性。根據X光光電子能譜儀分析製備的TaOx薄膜，並分析從X光光電子能譜儀所獲得的資料後，可以確認此薄膜是以TaO2的化合方式組成。製備完成的元件，在100毫伏電壓的操作下，可在有著雙極性電阻轉換特性的直流操作下運作超過100次的次數，並且有著超過10000秒的穩定記憶特性。在set操作中，載子傳導機制一開始是由歐姆傳輸主導，然後轉為在高阻態的空間電荷限制機制。最後在低阻態中，傳導機制又再一次的轉為歐姆傳輸。
另一部分則是敘述在室溫下，鉭摻雜的氧化矽薄膜製備電阻式隨機存取記憶體的製備方式與特性。從電流-電壓圖可以發現，在高阻態中，電流傳導機制首先是由在Ta:SiOx薄膜中本質載子所導致的歐姆傳輸機制所主導，之後轉為空間電荷限制電流機制。而在低阻態中，從高電壓到低電壓，電流傳導機制依序為Fowler–Nordheim穿隧機制，然後是空間電荷限制電流機制，最後為歐姆傳輸機制所主導。此外，製備完成的電阻式記憶體有著良好的耐用性與可靠度。
另一方面，在室溫下，我們研究以Ti/In2O3:SiO2/Pt為架構的電阻式隨機存取記憶體的製備方式與特性。製備完成的元件，在100毫伏電壓的操作下，可在有著雙極性電阻轉換特性的直流操作下運作超過100次的次數，並且有著超過10000秒的穩定記憶特性。在高阻態中，利用分析電流-電壓圖的方式，可以發現載子傳導機制的不對稱現象，並且利用能帶圖的方式來進行解釋。此外可以發現，電阻轉換是由於氧離子的遷移所造成的。
接著，在室溫下，我們研究以Ni/ZnO/HfO2/Ni為架構的電阻式隨機存取記憶體的製備方式與特性。製備完成的元件，有著雙極性電阻轉換特性，並在reset操作中，具有多層記憶的特性。此外，在較高的reset偏壓下，存在著兩個不同的reset階段。在第二次的reset階段後，利用第二次的set操作，元件可以回到初始位置。從這兩個階段的電流-電壓量測曲線中可以發現，電流傳導是由氧離子的遷移並與氧空缺複合所導致的蕭基發射機制所主導。這個現象會打斷傳導的燈絲，所以載子傳導機制轉換為蕭基發射機制，也導致元件從低阻態，轉換為高阻態。
最後，在室溫下，我們研究以Ti/MgZnO/Pt為架構的電阻式隨機存取記憶體的製備方式與特性。利用不同的停止電壓，在reset操作中，此元件可以獲得四個不同的電阻狀態。在100毫伏電壓的操作下，這四個電阻狀態有著有著超過10000秒的穩定的記憶特性，並且在沒有太多的退化之下，彼此可以清楚的被分辨出來。隨著停止電壓從1伏電壓上升到1.5伏電壓，電流傳導機制皆是由蕭基發射機制所主導。此外，我們利用能帶圖的方式來解釋多層電阻態的現象。

In this dissertation, some kinds of resistive random access memory (RRAM) devices with various kinds of oxide-based materials as the resistive switching layers are fabricated and its characteristics are investigated.
First, the fabrication and characterization of a RRAM with a Ti/TaO2/Pt structure at room temperature are reported. According to the X-ray photoelectron spectroscopy (XPS) analysis of the deposited TaOx film and the data fitting of the XPS spectrum data, the deposited TaOx film was then confirmed to be in the TaO2 phase. The fabricated device exhibits bipolar resistance switching behavior over one hundred DC switching cycles and shows stable retention characteristics for over 104 s under a 100 mV stress. It is also found that the electrical conduction mechanism in set process is firstly dominated by Ohmic conduction and then transforms to the space-charge-limited process in the high resistance state. Finally, the conduction mechanism turns to Ohmic conduction again in low resistance state.
The other part is described the fabrication and analysis of the RRAM cell with Ta dopant into silicon oxide layer by co-sputtering at room temperature. From the I-V measurements, it is found that the current conduction in high resistive state is first dominated by Ohmic conduction caused by the intrinsic carriers in the Ta:SiOx thin film and then turned to space-charge-limited-current mechanism. In low resistance state, the current conduction mechanism from higher voltage to lower voltage are dominated by Fowler–Nordheim tunneling and then SCLC mechanism, and finally dominated by Ohmic conduction mechanism. Furthermore, it is found that the fabricated Ti/Ta:SiOx/Pt RRAM cell is durable and reliable.
Additionally, the fabrication and characterization of resistance switching for a RRAM with a Ti/In2O3:SiO2/Pt structure in room temperature are reported. It is found that the device exhibited bipolar resistance switching behavior over one hundred switching cycles and shows stable retention characteristics for over 104 sec under 100mV stress condition. The asymmetric phenomenon of the carrier conduction mechanism at high resistance state is also explored by fitting the I-V curves and explained by the schematic energy band diagram. It is also found that the switching behavior is due to the migration of oxygen ions.
Furthermore, the fabrication and characterization of RRAM with Ni/ZnO/HfO2/Ni structure at room temperature are reported. It is found that the proposed device exhibited bipolar switching behavior with multilevel characteristics in reset process and it exhibited two-step reset stage under high reset bias. By applying a 2nd set process after the transformation of the 2nd reset stage, it is found that the RRAM can return to the initial state. From I-V curves measured in these two reset stages, it is found that the current conduction is dominated by Schottky emission due to the migration of oxygen ions and recombination with oxygen vacancies. This reaction can break the conducting filament so the carrier transport mechanism transforms to Schottky emission. This also results in the simultaneous transformation from low resistance state to high resistance state.
Finally, the fabrication and characterization of RRAM with Ti/MgZnO/Pt structure at room temperature were reported. Four different resistive states are obtained by applying different stop voltages for the reset process. These four resistance states show good retention characteristics without any degradation and can be clearly distinguished from one another by more than 10,000 second under 100mV stress. The current transport mechanism is dictated by a Schottky emission as the stop voltage increases from 1 to 1.5 V. The mechanism of multilevel RS is investigated and band diagrams are used to explain the multilevel RS phenomenon associated with Ti/MgZnO/Pt RRAM devices.

[1] Y. Xie, “Modeling, architecture, and applications for emerging memory technologies,” IEEE Des. Test Comput., vol. 28, pp. 44-50, 2011.
[2] M. F. Hung, Y. C. Wu, J. J. Chang, Chang Liao, and K. Shu, “Twin thin-film transistor nonvolatile memory with an Indium-Gallium-Zinc-Oxide Floating Gate,” IEEE Electron Device Lett., vol. 34, pp. 75-77, 2013.
[3] D. Jiang, M. Zhang, Z. Huo, Q. Wang, J. Liu, Z. Yu, X. Yang, Y. Wang, B. Zhang, J. Chen, and M. Liu, “A study of cycling induced degradation mechanisms in Si nanocrystal memory devices,” Nanotechnology, vol. 22, 254009, 2011.
[4] N. Setter, D. Damjanovic, L. Eng, G. Fox, S. Gevorgian, S. Hong, A. Kingon, H. Kohlstedt, N. Park, and G. Stephenson, “Ferroelectric thin films: Review of materials, properties, and applications,” J. Appl. Phys., vol. 100, 051606, 2006.
[5] A. Ney and J. S. Harris, “Reconfigurable magnetologic computing using the spin flop switching of a magnetic random access memory cell,” Appl. Phys. Lett., vol. 86, 013502, 2005.
[6] T. C. Chong, L. P. Shi, R. Zhao, P. K. Tan, J. M. Li, H. K. Lee, X. S. Miao, A. Y. Du, and C. H. Tung, “Phase change random access memory cell with superlattice-like structure,” Appl. Phys. Lett., vol. 88, 122114, 2006.
[7] H. S. P. Wong, H. Y. Lee, S. Yu, Y. S. Chen, Y. Wu, P. S. Chen, B. Lee, F. T. Chen, and M. J. Tsai, “Metal-Oxide RRAM,” Proc. IEEE, vol. 100, pp. 1951-1970, 2012.
[8] G. Muller, T. Happ, M. Kund, G. Y. Lee, N. Nagel, and R. Sezi, “Status and outlook of emerging nonvolatile memory technologies,” in IEEE Intl. Electron Devices Meeting, 2004, pp. 567-570.
[9] T. W. Hickmott, “Low-frequency negative resistance in thin anodic oxide films,” J. Appl. Phys., vol. 33, 2669, 1962.
[10] R. Waser and M. Aono, “Nanoionics-based resistive switching memories,” Nature Mater., vol. 6, pp. 833-840, 2007.
[11] R. Waser, R. Dittmann, G. Staikov, and K. Szot, “Redox‐based resistive switching memories–nanoionic mechanisms, prospects, and challenges,” Adv. Mater., vol. 21, pp. 2632-2663, 2009.
[12] W. Y. Chang, Y. T. Ho, T. C. Hsu, F. Chen, M. J. Tsai, and T. B. Wu, “Influence of crystalline constituent on resistive switching properties of TiO2 memory films,” Electrochem. Solid State Lett., vol. 12, pp. H135-H137, 2009.
[13] S. Maikap, D. Jana, M. Dutta, and A. Prakash, “Self-compliance RRAM characteristics using a novel W/TaOx/TiN structure,” Nanoscale Res. Lett., vol. 9, 292, 2014.
[14] S. Seo, M. J. Lee, D. H. Seo, E. J. Jeoung, D. S. Suh, Y. S. Joung, I. K. Yoo, I. R. Hwang, S. H. Kim, I. S. Byun, J. S. Kim, J. S. Choi, and B. H. Park, “Reproducible resistance switching in polycrystalline NiO films,” Appl. Phys. Lett., vol. 85, pp. 5655-5657, 2004.
[15] M. J. Lee, Y. Park, D. S. Suh, E. H. Lee, S. Seo, D. C. Kim, R. Jung, B. S. Kang, S. E. Ahn, and C. B. Lee, “Two series oxide resistors applicable to high speed and high density nonvolatile memory,” Adv. Mater., vol. 19, pp. 3919-3923, 2007.
[16] D. Panda, C. Y. Huang, and T. Y. Tseng, “Resistive switching characteristics of nickel silicide layer embedded HfO2 film,” Appl. Phys. Lett., vol. 100, 112901, 2012.
[17] H. Y. Lee, P. S. Che, T. Y. Wu, Y. S. Che, C. C. Wan, P. J. Tzen, C. H. Lin, F. Chen, C. H. Lien, and M. J. Tsai, “Low power and high speed bipolar switching with a thin reactive Ti buffer layer in robust HfO2 based RRAM,” in Tech. Dig. IEEE Int. Electron Devices Meeting, 2008, pp. 1-4.
[18] S. Y. Wang, C. W. Huang, D. Y. Lee, T. Y. Tseng, and T. C. Chang, “Multilevel resistive switching in Ti/CuxO/Pt memory devices,” J. Appl. Phys., vol. 108, 114110, 2010.
[19] C. Yoshida, K. Tsunoda, H. Noshiro, and Y. Sugiyama, “High speed resistive switching in Pt/TiO2/TiN film for nonvolatile memory application,” Appl. Phys. Lett., vol. 91, 223510, 2007.
[20] W. C. Chien, Y. C. Chen, E. K. Lai, Y. Y. Lin, K. P. Chang, Y. D. Yao, P. Lin, J. Gong, S. C. Tsai, and C. H. Lee, “High-speed multilevel resistive RAM using RTO WOX,” in International Conference on Solid State Devices and Materials (SSDM), 2009, pp. 1206-1207.
[21] M. Terai, Y. Sakotsubo, S. Kotsuji, and H. Hada, “Resistance Controllability of Ta2O5/TiO2 Stack ReRAM for Low-Voltage and Multilevel Operation,” IEEE Electron Device Lett., vol. 31, pp. 204-206, 2010.
[22] T. M. Tsai, K. C. Chang, T. C. Chang, Y. E. Syu, S. L. Chuang, G. W. Chang, G. R. Liu, M. C. Chen, H. C. Huang, S. K. Liu, Y. H. Tai, D. S. Gan, Y. L. Yang, T. F. Young, B. H. Tseng, K. H. Chen, M. J. Tsai, C. Ye, H. Wang, and S. M. Sze, “Bipolar resistive RAM characteristics induced by nickel incorporated into silicon oxide dielectrics for IC applications,” IEEE Electron Device Lett., vol. 33, pp. 1696-1698, 2012.
[23] K. C. Chang, T. M. Tsai, T. C. Chang, Y. E. Syu, S. L. Chuang, C. H. Li, D. S. Gan, and S. M. Sze, “The effect of silicon oxide based RRAM with tin doping,” Electrochem. Solid State Lett., vol. 15, pp. H65-H68, 2012.
[24] Y. T. Chen, T. C. Chang, J. J. Huang, H. C. Tseng, P. C. Yang, A. K. Chu, J. B. Yang, H. C. Huang, D. S. Gan, M. J. Tsai, and S. M. Sze, “Influence of molybdenum doping on the switching characteristic in silicon oxide-based resistive switching memory,” Appl. Phys. Lett., vol. 102, 043508, 2013.
[25] K. C. Chang, T. M. Tsai, T. C. Chang, Y. E. Syu, C. C. Wang, S. L. Chuang, C. H. Li, D. S. Gan, and S. M. Sze, “Reducing operation current of Ni-doped silicon oxide resistance random access memory by supercritical CO2 fluid treatment,” Appl. Phys. Lett., vol. 99, 263501, 2011.
[26] W. K. Hsieh, K. T. Lam, and S. J. Chang, “Asymmetric resistive switching characteristics of In2O3:SiO2 cosputtered thin film memories,” J. Vac. Sci. Technol. B, vol. 32, 020603, 2014.
[27] 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, “Improvement of resistive memory switching in NiO using IrO2,” Appl. Phys. Lett., vol. 88, 232106, 2006.
[28] Z. Fang, H. Y. Yu, W. J. Liu, Z. R. Wang, X. A. Tran, B. Gao, and J. F. Kang, “Temperature instability of resistive switching on HfOx-based RRAM devices,” IEEE Electron Device Lett., vol. 31, pp. 476-478, 2010.
[29] W. C. Chien, Y. C. Chen, E. K. Lai, Y. D. Yao, P. Lin, S. F. Horng, J. Gong, T. H. Chou, H. M. Lin, M. N. Chang, Y. H. Shih, K. Y. Hsieh, R. Liu, and C. Y. Lu, “Unipolar switching behaviors of RTO WOX RRAM,” IEEE Electron Device Lett., vol. 31, pp. 126-128, 2010.
[30] S. Yu and H.-S. P. Wong, “Compact modeling of conducting-bridge random-access memory (CBRAM),” IEEE T. Electron Dev., vol. 58, pp. 1352-1360, 2011.
[31] S. M. Lin, J. Y. Tseng, T. Y. Su, Y. C. Shih, J. S. Huang, C. H. Huang, S. J. Lin, and Y. L. Chueh, “Tunable multilevel storage of complementary resistive switching on single-step formation of ZnO/ZnWOx bilayer structure via interfacial engineering,” Acs Appl. Mater. Inter., vol. 6, pp. 17686-17693, 2014.
[32] A. Sawa, “Resistive switching in transition metal oxides,” Mater. Today, vol. 11, pp. 28-36, 2008.
[33] M. Janousch, G. I. Meijer, U. Staub, B. Delley, S. F. Karg, and B. P. Andreasson, “Role of oxygen vacancies in Cr-doped SrTiO3 for resistance-change memory,” Adv. Mater., vol. 19, pp. 2232-2235, 2007.
[34] H. A. Fowler, J. E. Devaney, and J. G. Hagedorn, “Growth model for filamentary streamers in an ambient field,” IEEE T. Dielect. El. In., vol. 10, pp. 73-79, 2003.
[35] M. Fujimoto, H. Koyama, M. Konagai, Y. Hosoi, K. Ishihara, S. Ohnishi, and N. Awaya, “TiO2 anatase nanolayer on TiN thin film exhibiting high-speed bipolar resistive switching,” Appl. Phys. Lett., vol. 89, 223509, 2006.
[36] T. C. Chang, F. Y. Jian, S. C. Chen, and Y. T. Tsai, “Developments in nanocrystal memory,” Mater. Today, vol. 14, pp. 608-615, 2011.
[37] W. R. Chen, T. C. Chang, P. T. Liu, P. S. Lin, C. H. Tu, and C. Y. Chang, “Formation of stacked Ni silicide nanocrystals for nonvolatile memory application,” Appl. Phys. Lett., vol. 90, 112108, 2007.
[38] G. Asano, H. Morioka, H. Funakubo, T. Shibutami, and N. Oshima, “Fatigue-free RuO2/Pb(Zr,Ti)O3/RuO2 capacitor prepared by metalorganic chemical vapor deposition at 395 °C,” Appl. Phys. Lett., vol. 83, pp. 5506-5508, 2003.
[39] S. Y. Wang, D. Y. Lee, T. Y. Huang, J. W. Wu, and T. Y. Tseng, “Controllable oxygen vacancies to enhance resistive switching performance in a ZrO2-based RRAM with embedded Mo layer,” Nanotechnology, vol. 21, 495201, 2010.
[40] M. K. Yang, J. W. Park, T. K. Ko, and J. K. Lee, “Bipolar resistive switching behavior in Ti/MnO2/Pt structure for nonvolatile memory devices,” Appl. Phys. Lett., vol. 95, 042105, 2009.
[41] I. C. Yao, D. Y. Lee, T. Y. Tseng, and P. Lin, “Fabrication and resistive switching characteristics of high compact Ga-doped ZnO nanorod thin film devices,” Nanotechnology, vol. 23, 145201, 2012.
[42] L. Zhang, R. Huang, M. Zhu, S. Qin, Y. Kuang, D. Gao, C. Shi, and Y. Wang, “Unipolar TaOx-based resistive change memory realized with electrode engineering,” IEEE Electron Device Lett., vol. 31, pp. 966-968, 2010.
[43] A. Prakash, S. Maikap, H. C. Chiu, T. C. Tien, and C. S. Lai, “Enhanced resistive switching memory characteristics and mechanism using a Ti nanolayer at the W/TaOx interface,” Nanoscale Res. Lett., vol. 9, pp. 1-9, 2013.
[44] H. K. Yoo, B. S. Kang, and S. B. Lee, “Forming time of conducting channels in double-layer Pt/Ta2O5/TaOx/Pt and single-layer Pt/TaOx/Pt resistance memories,” Thin Solid Films, vol. 540, pp. 190-193, 2013.
[45] J. M. Sanz and S. Hofmann, “Auger-electron spectroscopy and x-ray photoelectron-spectroscopy studies of the oxidation of polycrystalline tantalum and niobium at room-temperature and low oxygen pressures,” Journal of the Less-Common Metals, vol. 92, pp. 317-327, 1983.
[46] S. G. Park, M. K. Blanka, and Y. Nishi, “Impact of oxygen vacancy ordering on the formation of a conductive filament in TiO2 for resistive switching memory,” IEEE Electron Device Lett., vol. 32, pp. 197-199, 2011.
[47] N. Lu, L. Li, P. Sun, M. Wang, Q. Liu, H. Lv, S. Long, and M. Liu, “A novel method of identifying the carrier transport path in metal oxide resistive random access memory,” J Phys. D Appl. Phys., vol. 48, 065101, 2015.
[48] N. Lu, L. Li, P. Sun, M. Wang, Q. Liu, H. Lv, S. Long, W. Banerjee, and M. Liu, “Carrier-transport-path-induced switching parameter fluctuation in oxide-based resistive switching memory,” Materials Research Express, vol. 2, 046304, 2015.
[49] R. Dong, D. S. Lee, W. F. Xiang, S. J. Oh, D. J. Seong, S. H. Heo, H. J. Choi, M. J. Kwon, S. N. Seo, M. B. Pyun, M. Hasan, and H. Hwang, “Reproducible hysteresis and resistive switching in metal-CuxO-metal heterostructures,” Appl. Phys. Lett., vol. 90, 042107, 2007.
[50] M. Fujimoto, H. Koyama, S. Kobayashi, Y. Tamai, N. Awaya, Y. Nishi, and T. Suzuki, “Resistivity and resistive switching properties of Pr0.7Ca0.3MnO3 thin films,” Appl. Phys. Lett., vol. 89, 243504, 2006.
[51] M. H. Lin, M. C. Wu, C. H. Lin, and T. Y. Tseng, “Resistive switching characteristics and mechanisms of Pt-embedded SrZrO3 memory devices,” J. Appl. Phys., vol. 107, 124117, 2010.
[52] C. Y. Liu, Y. H. Huang, J. Y. Ho, and C. C. Huang, “Retention mechanism of Cu-doped SiO2-based resistive memory,” J Phys. D Appl. Phys., vol. 44, 205103, 2011.
[53] S. H. Liu, W. L. Yang, Y. H. Lin, C. C. Wu, and T. S. Chao, “Novel ion bombardment technique for doping limited Cu source in SiOx-based nonvolatile switching layer,” IEEE Electron Device Lett., vol. 34, pp. 1388-1390, 2013.
[54] M. C. Chen, T. C. Chang, C. T. Tsai, S. Y. Huang, S. C. Chen, C. W. Hu, S. M. Sze, and M. J. Tsai, “Influence of electrode material on the resistive memory switching property of indium gallium zinc oxide thin films,” Appl. Phys. Lett., vol. 96, 262110, 2010.
[55] W. J. Chun, A. Ishikawa, H. Fujisawa, T. Takata, J. N. Kondo, M. Hara, M. Kawai, Y. Matsumoto, and K. Domen, “Conduction and valence band positions of Ta2O5, TaON, and Ta3N5 by UPS and electrochemical methods,” J. Phys. Chem. B, vol. 107, pp. 1798-1803, 27 2003.
[56] J. G. S. Moo, Z. Awaludin, T. Okajima, and T. Ohsaka, “An XPS depth-profile study on electrochemically deposited TaOx,” J Solid State Electr, vol. 17, pp. 3115-3123, 2013.
[57] S. M. Sze and K. K. Ng, Physics of Semiconductor Devices, 3rd ed. Hoboken NJ: Wiley, 2006, pp. 227-229.
[58] J. Lu, T. C. Chang, Y. T. Chen, J. J. Huang, P. C. Yang, S. C. Chen, H. C. Huang, D. S. Gan, N. J. Ho, Y. Shi, and A. K. Chu, “Enhanced retention characteristic of NiSi2/SiNx compound nanocrystal memory,” Appl. Phys. Lett., vol. 96, 262107, 2010.
[59] Y. S. Fan, P. T. Liu, L. F. Teng, and C. H. Hsu, “Bipolar resistive switching characteristics of Al-doped zinc tin oxide for nonvolatile memory applications,” Appl. Phys. Lett., vol. 101, 052901, 2012.
[60] D. Y. Lee and T. Y. Tseng, “Forming-free resistive switching behaviors in Cr-embedded Ga2O3 thin film memories,” J. Appl. Phys., vol. 110, 114117, 2011.
[61] P. C. Yang, T. C. Chang, S. C. Chen, Y. S. Lin, H. C. Huang, and D. S. Gan, “Influence of bias-induced copper diffusion on the resistive switching characteristics of a SiON thin film,” Electrochem. Solid State Lett., vol. 14, pp. H93-H95, 2011.
[62] J. J. Huang, T. C. Chang, P. C. Yang, Y. T. Chen, H. C. Tseng, J. B. Yang, S. M. Sze, A. K. Chu, and M. J. Tsai, “Influence of forming process on resistance switching characteristics of In2O3/SiO2 bi-layer,” Thin Solid Films, vol. 528, pp. 31-35, 2013.
[63] C. W. Hsu, T. H. Hou, M. C. Chen, I. T. Wang, and C. L. Lo, “Bipolar Ni/TiO2/HfO2/Ni RRAM with multilevel states and self-rectifying characteristics,” IEEE Electron Device Lett., vol. 34, pp. 885-887, 2013.
[64] Y. H. Tseng, C. E. Huang, C. Kuo, Y. D. Chih, and C. J. Lin, “High density and ultra small cell size of contact ReRAM (CR-RAM) in 90nm CMOS logic technology and circuits,” in IEDM Tech. Dig., 2009, pp. 1-4.
[65] Y. Bai, H. Wu, Y. Zhang, M. Wu, J. Zhang, N. Deng, H. Qian, and Z. Yu, “Low power W: AlOx/WOx bilayer resistive switching structure based on conductive filament formation and rupture mechanism,” Appl. Phys. Lett., vol. 102, 173503, 2013.
[66] W. Y. Chang, Y. C. Lai, B. WuTai, S. F. Wang, F. Chen, and M. J. Tsai, “Unipolar resistive switching characteristics of ZnO thin films for nonvolatile memory applications,” Appl. Phys. Lett., vol. 92, 022110, 14 2008.
[67] N. Xu, L. Liu, X. Sun, X. Liu, D. Han, Y. Wang, R. Han, J. Kang, and B. Yu, “Characteristics and mechanism of conduction/set process in TiN/ZnO/Pt resistance switching random-access memories,” Appl. Phys. Lett., vol. 92, 232112, 2008.
[68] H. Yong, C. Kyoungah, and K. Sangsig, “Characteristics of multilevel bipolar resistive switching in Au/ZnO/ITO devices on glass,” Microelectron Eng., vol. 88, pp. 2608-2610, 2011.
[69] W. K. Hsieh, K. T. Lam, and S. J. Chang, “Characteristics of tantalum-doped silicon oxide-based resistive random access memory,” Mat. Sci. Semicon. Proc., vol. 27, pp. 293-296, 2014.
[70] W. K. Hsieh, K. T. Lam, and S. J. Chang, “Bipolar Ni/ZnO/HfO2/Ni RRAM with multilevel characteristic by different reset bias,” Mat. Sci. Semicon. Proc., vol. 35, pp. 30-33, 2015.
[71] C. C. Shih, K. C. Chang, T. C. Chang, T. M. Tsai, R. Zhang, J. H. Chen, K. H. Chen, T. F. Young, H. L. Chen, J. C. Lou, T. J. Chu, S. Y. Huang, D. H. Bao, and S. M. Sze, “Resistive switching modification by ultraviolet illumination in transparent electrode resistive random access memory,” IEEE Electron Device Lett., vol. 35, pp. 633-635, 2014.
[72] S. Kim, H. Moon, D. Gupta, S. Yoo, and Y. K. Choi, “Resistive switching characteristics of sol–gel zinc oxide films for flexible memory applications,” IEEE T. Electron Dev., vol. 56, pp. 696-699, 2009.
[73] J. Y. Li, S. P. Chang, H. H. Lin, and S. J. Chang, “High responsivity MgxZn1-xO film UV photodetector grown by RF sputtering,” IEEE Phontic Tech. L., vol. 27, pp. 978-981, 2015.
[74] T. H. Wu, I. C. Cheng, C. C. Hsu, and J. Z. Chen, “UV photocurrent responses of ZnO and MgZnO/ZnO processed by atmospheric pressure plasma jets,” J. Alloy Compd., vol. 628, pp. 68-74, 2015.
[75] S. Gao, C. Song, C. Chen, F. Zeng, and F. Pan, “Dynamic processes of resistive switching in metallic filament-based organic memory devices,” J. Phys. Chem. C, vol. 116, pp. 17955-17959, 2012.
[76] S. Gao, F. Zeng, F. Li, M. Wang, H. Mao, G. Wang, C. Song, and F. Pan, “Forming-free and self-rectifying resistive switching of the simple Pt/TaOx/n-Si structure for access device-free high-density memory application,” Nanoscale, vol. 7, pp. 6031-6038, 2015.
[77] Y. Hou, Z. Mei, H. Liang, D. Ye, C. Gu, X. Du, and Y. Lu, “Annealing Effects of Ti/Au Contact on n-MgZnO/p-Si Ultraviolet-B Photodetectors,” IEEE T. Electron Dev., vol. 60, pp. 3474-3477, 2013.