在本論文中，首先針對以聚甲基丙烯酸甲酯(PMMA)和聚甲基丙烯酸羥乙酯(PHEMA)製作之兩種有機非揮發性電阻式記憶體，作詳細的電特性及記憶體轉換特性的探討。由實驗結果得知兩種元件的電流在OFF狀態時，都是以熱產生自由載子 (Thermally generated free carriers)和空間電荷侷限電流 (Space charge limited current)這兩種理論模型作為傳導，當元件切換到ON狀態後，載子則是以歐姆定律的型式流動，而這兩種元件的ON/OFF轉換特性都是由燈絲傳導機制(Filamentary conduction)所造成，其機制可由元件轉換到ON狀態的限制電流和轉換到OFF狀態前的最高電流的線性關係所證明。這兩種元件都有不錯的狀態切換的能力(~500次)和開關電流比(~104)，而元件都可以在一萬秒內保持穩定的ON和OFF狀態。
然而以硒化鎘/硫化鋅無機量子點(CdSe/ZnS QDs)來製作記憶體元件是本論文的研究重點，元件的做法是將量子點先溶於PMMA溶液，再以旋轉塗佈的方式製作，當PMMA和量子點的溶質比為2:1時，元件有最大的電流比(208.3)，而在元件的有機層上沉積一層氟化鋰(LiF)時，可以改善元件良率的問題，當LiF厚度為1.5奈米時，元件有最大的良率(71.4 %)。由記憶體特性的量測中可知元件有不錯的穩定性，ON和OFF狀態都可以持續穩定維持一萬秒，而元件重複寫入和抹除的能力和設定的操作電壓有關，當寫入、抹除、讀取電壓分別設在4、10和0.1伏特時，元件的切換次數可以超過4000次，而開關電流比大約在160，因此此量子點元件有不錯的記憶體特性。

In the thesis, the resistive switching devices of metal/insulator/metal (MIM) structure with poly(2-hydroxyethyl methacrylate) PHEMA and poly(methyl methacrylate) PMMA have been fabricated and characterized. The operation mechanisms of the fabricated devices are analyzed by theoretical models. The conduction mechanisms of both of the PHEMA- and PMMA-devices at OFF state are attributed to the thermally generated free carriers and space charge limited current, while the current transport at ON state appears to abide the Ohm's Law. The switching behaviors observed in both devices are due to the filamentary conduction mechanism, which can be confirmed by the relationship between the turn-on compliance current and turn-off current. The PHEMA- and PMMA-devices demonstrate a good switching property (~500 cycles), large on/off current ratio (~104). Moreover, the ON and OFF state current are stable for 104 seconds at a reading voltage of +1 V.
Additionally, this article also presents nonvolatile memory property on a single active layer formed by spin coating the blend solution of the inorganic semiconductor CdSe/ZnS quantum dots (QDs) and PMMA. The largest on/off current ratio (208.3) is observed in the devices with blends of 2 wt% PMMA and 1 wt% QDs which thickness is 100 nm. LiF buffer layer has been deposited on blend layer, which can improve the yield rate of the fabricated devices. When the thickness of LiF is equal to1.5 nm, the yield rate of the memory devices is the largest (71.4%). ON and OFF state current of the devices are stable for 104 s with +1 V reading voltage. In addition, the rewritable/re-erasable (switching) ability and On/Off current ratio of the device are associated with the write/erase voltage. The writing, erasing and reading voltage equal to 4, 10 and 0.1 V, respectively, the switching ability can be up to 4000 times and On/Off current ratio is about 160 with +1 V reading voltage. Therefore, the device with QDs shows excellent memory properties.

Bibliography-Chapter 1
[1] Q. Ling, D. Liaw, C. Zhu, D. S. Chan, E. Kang, K. Neoh, “Polymer electronic memories: Materials, devices and mechanisms,” Polymer, vol. 33, issue 10, pp. 917–978, Oct. 2008.
[2] Waser R., “Nanoelectronics and information technology: advanced electronic materials and novel devices. 2nd ed.,” Weinheim: Wiley-VCH; 2005
[3] R. F. Service, “Next-generation technology hits an early midlife crisis,” Science, vol. 302, pp. 556-557, Oct. 2003
[4] R. Compano, “Trends in nanoelectronics,” Nanotechnol., vol. 12, no. 2, pp. 85-88, Apr. 2001
[5] L.E. Yu, S.Kim, M. K. Ryu, S. Y.Choi, and Y. K.Choi, “Structure Effects on Resistive Switching of Al/TiOx/Al Devices for RRAM Applications,” IEEE Electron Device Lett., vol. 29, no. 4, pp. 331, Apr. 2008.
[6] The International Technology Roadmap for Semiconductors (ERD_ERM_2010 FINAL Report Memory Assessment ITRS), p. 19
[7] I. G. Baek, D. C. Kim, M.J. Lee, H. -J. Kim, E. K. Yim, M. S. Lee, J. E. Lee, S. E. Ahn, S. Seo, J. H. Lee, J. C. Park, Y. K. Cha, S. O. Park, H. S. Kim, I. K. Yoo, U-In Chung, J. T. Moon, B. I. Ryu, “Multi-layer cross-point binary oxide resistive memory (OxRRAM) for post-NAND storage application,” Int. Electron Devices Meet., pp. 750-753, Dec. 2005
[8] Y. T. Tsai, T. C. Chang, C. C. Lin, S. C. Chen, C. W. Chen, S. M. Sze, F. S. Yeh, T. Y. Tseng, “Influence of Nanocrystals on Resistive Switching Characteristic in Binary Metal Oxides Memory Devices,” Electrochem. Solid-State Lett., vol. 14, issue 3, pp. 135-138, 2011
[9] S. Seo, M. J. Lesse, 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,” Appl. Phys. Lett., vol. 85, no. 23, pp. 5655–5657, Dec. 2004.
[10] L. E. Yu, S. Kim, M. K. Ryu, S. Y. Choi, and Y. K. Choi, “Structure effects on resistive switching of Al/TiOx/Al devices for RRAM applications,” IEEE Electron Device Lett., vol. 29, no. 4, pp. 331–333, Apr. 2008.
[11] A. Chen, S. Haddad, Y.-C. Wu, T.-N. Fang, Z. D. Lan, S. Avanzino, S. Pangrle, M. Buynoski, M. Rathor, W. Cai, N. Tripsas, C. Bill, M. VanBuskirk, and M. Taguchi, “Non-volatile resistive switching for advanced memory applications,” Int. Electron Devices Meet., pp. 746–749. , Dec. 2005
[12] A. Beck, J. G. Bednorz, C. Gerber, C. Rossel, and D. Widmer, “Reproducible switching effect in thin oxide films for memory applications,” Appl. Phys. Lett., vol. 77, no. 1, pp. 139–141, Jul. 2000.
[13] S. Q. Liu, N. J. Wu, and A. Ignatiev, “Electric-pulse-induced reversible resistance change effect in magnetoresistive films,” Appl. Phys. Lett., vol. 76, no. 19, pp. 2749–2751, Mar. 2000
[14] S. F. Karg, G. I. Meijer, J. G. Bednorz, C. T. Rettner, A. G. Schrott, E. A. Joseph, C. H. Lam, M. Janousch, U. Staub, F. La Mattina, S. F. Alvarado, D. Widmer, R. Stutz, U. Drechsler, D. Caimi, “Transition-metal-oxide-based resistance-change memories,” IBM J. Res and Dev, vol. 52, no. 4, pp. 481-492, Jul. 2008
[15] A. Sawa, T. Fujii, M. Kawasaki, and Y. Tokura, “Colossal Electro-Resistance Memory Effect at Metal/La2CuO4 Interfaces,” Jpn. J. Appl. Phys., vol 44, pp. 1241-1243, Sep. 2005
[16] B. Mukherjee and A. J. Pal, “Multilevel conductance and memory in ultrathin organic films,” Appl. Phys. Lett., vol. 85, pp. 2116-2118, Jul. 2004
[17] L. Ma, S. Pyo, J. Ouyang, Q. Xu, and Y. Yang, “Nonvolatile electrical bistability of organic/metal-nanocluster/organic system,” Appl. Phys. Lett., vol 82, pp. 1419-1421, Jan. 2003
[18] T. Oka ,and N. Nagaosa, “Interfaces of Correlated Electron Systems: Proposed Mechanism for Colossal Electroresistance,” Phys. Rev. Lett., vol 95, pp. 266403-266406, Dec. 2005
[19] S. Kim, and Y. K. Choi, “A Comprehensive Study of the Resistive Switching Mechanism in Al/TiOx/TiO2/Al-Structured RRAM,” IEEE Trans. Electron Devices, vol. 56, no. 12, pp. 3049-3054, Dec. 2009
[20] T. Fujii, M. Kawasaki, A. Sawa, H. Akoh, Y. Kawazoe, and Y. Tokura, “Hysteretic current-voltage characteristics and resistance switching at an epitaxial oxide Schottky junction SrRuO3/SrTi0.99Nb0.01O3,” Appl. Phys. Lett., vol. 86, no. 1, pp. 012107-012109, Jan. 2005
[21] A. Sawa, T. Fujii, M. Kawasaki, and Y. Tokura, “Hysteretic current-voltage characteristics and resistance switching at a rectifying Ti/Pr0.7Ca0.3MnO3 interface,” Appl. Phys. Lett., vol. 85, no. 18, pp. 4073–4075, Nov. 2004
[22] M. Mitkova, Y. Wang, and P. Boolchand, “Dual chemical role of Ag as an additive in chalcogenide glasses,” Phys. Rev. Lett., vol. 83, no. 19, pp. 3848–3851, Nov. 1999
[23] A. Odagawa, H. Sato, I. H. Inoue, H. Akoh, M. Kawasaki, and Y. Tokura, “Colossal electroresistance of a Pr0.7Ca0.3MnO3 thin film at room temperature,” Phys. Rev. B, vol. 70, no. 22, pp. 224403-224406, Dec. 2004
[24] C. H. Tu, Y. S. Lai, and D. L. Kwon, “Memory Effect in the Current–Voltage Characteristic of 8-Hydroquinoline Aluminum Salt Films,” IEEE Electron Dev. Lett., Vol. 27, no. 5, pp. 354-356, May 2006
[25] J. Kevorkian, M. M. Labes, D. C. Larson, and D. C. Wu, “Bistable switching in organic thin films,” Discuss. Faraday Soc., vol. 51, pp.139-143, 1971
[26] L. Ma, J. Liu, and Y. Yang, “Organic electrical bistable devices and rewritable memory cells,” Appl. Phys. Lett., Vol. 80, no. 16, pp. 2997-2999, Feb. 2002
[27] J. Wu, L. P. Ma, and Y. Yang, “Single-band Hubbard model for the transport properties in bistable organic/metal nanoparticle/organic devices,” Phys. Rev. B, vol. 69, no. 11, pp. 115321-115328, Mar. 2004
[28] L. D. Bozano, B. W. Kean, V. R. Deline, J. R. Salem, and J. C. Scott, “Mechanism for bistability in organic memory elements,” Appl. Phys. Lett., vol. 84, no.4, pp. 607-609, Jan. 2004
[29] P. Y. Lai, “Investigation and characterization of Au nanoparticles incorporated polymer thin films for nonvolatile resistance random access memories,” Department of Materials Science and Engineering, p. 5, 2010
[30] Y. S. Lai, C. H. Tu, D. L. Kwong, J. S. Chen, “Bistable resistance switching of poly(N-vinylcarbazole) films for nonvolatile memory applications,” Appl. Phys. Lett., vol. 87, no. 12, pp. 122101-122103, Sep. 2005
[31] W. L. Kwan, B. Lei, Y. Shao, S. V. Prikhodko, Noah Bodzin, and Y. Yang, “Direct observation of localized conduction pathways in photocross-linkable polymer memory,” J. Appl. Phys., vol. 105, no. 12, pp. 124516-124520, Jun. 2009
[32] S. Baek, D. Lee, J. Kim, S. H. Hong, O. Kim, and M. Ree, “Novel Digital Nonvolatile Memory Devices Based on Semiconducting Polymer Thin Films,” Adv. Funct. Mater., Vol. 17, no. 15, pp. 2637–2644, Oct. 2007
[33] A. Prakash, J. Ouyang, J. L. Lin, and Y. Yang, “Polymer memory device based on conjugated polymer and gold nanoparticles,” J. Appl. Phys., vol. 100, no. 5, pp. 054309-054313, Sep. 2006
[34] K. S. Yook , S. O. Jeon, C. W. Joo, J. Y. Lee, S. H. Kim, and J. Jang, “Organic bistable memory device using MoO3 nanocrystal as a charge trapping center,” Org. Electr., vol. 10, no. 1, pp. 48–52, Feb. 2009
[35] P. F. Lee, and J. Y. Dai, “Memory effect of an organic based trilayer structure with Au nanocrystals in an insulating polymer matrix,” Nanotechnol., vol. 21, no. 29, pp. 295706-295710, Jul. 2010
[36] S. H. Kang, C. K. Kumar, Z. Lee, V. Radmilovic, and E. T. Kim, “Effects of surface ligands on the charge memory characteristics of CdSe/ZnS nanocrystals in TiO2 thin film,” Appl. Phys. Lett., vol. 95, no. 18, pp. 183111-183113, Nov. 2009

Bibliography-Chapter 2
[1] Tyczkowski J., “Bistable switching in plasma-polymerized acrylonitrile films,” Thin Solid Films, vol. 199, no. 2, pp. 335-342, Apr. 1991
[2] D. Adler, “Amorphous semiconductors,” CRC Press (Cleveland, OH), 1971.
[3] D. A. Seanor, “Electrical properties of polymers,” Academic Press (New York), 1982
[4] H. S. Nalwa, “Ferroelectric Polymers: Chemistry: Physics, and Applications,” CRC Press (New York), pp. 1–62., 1995
[5] Q. Ling, D. Liaw, C. Zhu, D. S. Chan, E. Kang, and K. Neoh, “Polymer electronic memories: Materials, devices and mechanisms,” Polymer, vol. 33, no. 10, pp. 917–978, Oct. 2008
[6] S. M. Sze, “Physics of semiconductor devices”, second ed., Wiley (New York), p. 403, 1981
[7] P. Y. Lai, “Investigation and characterization of Au nanoparticles incorporated polymer thin films for nonvolatile resistance random access memories,” Department of Materials Science and Engineering, p. 5, 2010
[8] J. Kevorkian, M. M. Labes, D. C. Larson, and D. C. Wu, “Bistable switching in organic thin films,” Discuss. Faraday Soc., vol. 51, pp.139-143, 1971
[9] H. K. Henisch, and W. R. Smith, “Switching in organic polymer films,” Appl. Phys. Lett., vol. 24, no. 12, pp. 589-591, Jun. 1974
[10] T. Kaplan, and D. Adler D, “Electrothermal switching in amorphous semiconductors,” J. Non-Cryst. Solids, vol. 8–10, pp. 538-543, Jun. 1972
[11] W. L. Kwan, B. Lei, Y. Shao, S. V. Prikhodko, N. Bodzin, and Y. Yang, “Direct observation of localized conduction pathways in photocross-linkable polymer memory,” J. Appl. Phys., vol. 105, no. 12,pp. 124516-124520, Jun. 2009
[12] C. T. Lee, L. Z. Yu, and H. C. Chen, “Memory bistable mechanisms of organic memory devices,” Appl. Phys. Lett., vol. 97, no. 4, pp. 043301-043303, Jul. 2010
[13] Y. S. Lai, C. H. Tu, D. L. Kwong, and J. S. Chen, “Bistable resistance switching of poly(N-vinylcarbazole) films for nonvolatile memory applications,” Appl. Phys. Lett., vol. 87, no. 12, pp. 122101-122103, Sep. 2005
[14] D. M. Taylor, “Space charges and traps in polymer electronics,” IEEE Trans. Dielect. Electr. Insulation, vol. 13, no. 5, pp. 1063-1073, Oct. 2006
[15] L. D. Bozano, B. W. Kean, M. Beinhoff, K. R. Carter, P. M. Rice, and J. C. Scott, “Organic materials and thin-film structures for cross-point memory cells based on tapping in metallic nanoparticles,” Adv. Funct. Mater., vol. 15, no. 12, pp. 1933-1939, Dec. 2005
[16] H. T. Lin, Z. Pei, and Y. J. Chan, “Carrier transport mechanism in a nanoparticle- incorporated organic bistable memory device” IEEE Electron Device Lett., vol. 28, no. 7, pp. 569-571, Jul. 2007
[17] R. S. Potember, T. O. Poehler, and D. O. Cowan, “Electrical switching and memory phenomena in Cu-TCNQ thin films” Appl. Phys. Lett., vol. 34, no. 6, pp. 405-411, Mar. 1979
[18] J. P. Farges, “Organic conductors : fundamentals and applications”, Marcel Dekker (New York), 1994

Bibliography-Chapter 4
[1] T. W. Kim, S. H. Oh, H. Choi, G. Wang, H. Hwang,D. Y. Kim, and T. Lee, “Reversible switching characteristics of polyfluorene-derivative single layer film for nonvolatile memory devices,” Appl. Phys. Lett., vol. 92, no. 25, pp. 253308-253310, Jun. 2008
[2] X. D. Zhuang, Y. Chen, G. Liu, P. P. Li, C. X. Zhu, E. T. Kang, K. G. Noeh, B. Zhang, J. H. Zhu, and Y. X. Li, “Conjugated-polymer-functionalized graphene oxide: Synthesis and nonvolatile rewritable memory effect,” Adv. Mater., vol. 22, no. 15, pp. 1731-1735, Apr. 2010