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Tan, Scott H. (Scott Howard). "Neuromorphic computing systems : crystalline resistive random access memory." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127915.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, May, 2020<br>Cataloged from the official PDF of thesis.<br>Includes bibliographical references (pages 129-142).<br>Neuromorphic computing is a promising approach for efficient electronics by shaping computer hardware like the human brain. At the core of neuromorphic architectures are artificial synapses, which store conductance states to weight collections of electrical spikes according to Kirchoff's laws and Ohm's law. This thesis presents Silicon (Si)-based crystalline resistive random-access memory (crystalline RRAM) artificial synapses for neuromorphic computing. The main scaling bottleneck is poor temporal and spatial uniformity of artificial synapses. To the best of the author's knowledge, crystalline RRAM reported in this thesis have the lowest switching variations compared to other RRAM types. Controlling metal movement in resistive switching materials is extremely challenging. This thesis demonstrates two strategies to improve nanoscale control in crystalline RRAM: 1) intrinsic semiconductor regulation and 2) active metal alloying.<br>The first strategy relies on using defects to regulate resistive switching. Epitaxially-grown Silicon-Germanium (SiGe) on Si permits resistive switching via dislocations. Defect-selective chemical etching can increase ON/OFF ratio while maintaining low variations. The second approach to improve crystalline RRAM is active metal alloying. Pure silver (Ag) exhibits high mobility in Si due to thermodynamic repulsion between Ag and Si. Thermodynamic instability of Ag in Si induces poor weight stability, especially in low conductance states. This thesis demonstrates that adding a small amount of copper (Cu) to pure Ag can enhance weight stability because Cu can act as a bridge between Ag and Si to alleviate thermodynamic repulsion. Convolutional filtering and weight storage with 32 x 32 crystalline RRAM crossbar arrays are experimentally demonstrated using this approach. While these results are extremely promising, 2D crossbar scaling is limited by sneak currents.<br>Stacking artificial synapses in 3D could maximize scaling potential. However, 3D crystalline RRAM cannot be fabricated with single-crystalline materials that require high growth temperatures. Poly-crystalline Si could form 3D crystalline RRAM, however, resistive switching performance is inferior to single-crystalline RRAM, possibly due to free bonds. This thesis demonstrates hydrogen passivation can fix this problem. Hydrogenated doped poly-crystalline/micro-crystalline Si are presented as suitable materials for 3D neuromorphic computing cores. To conclude this thesis, monolithic character classifiers with micro-crystalline imaging and computing units are designed.<br>by Scott H. Tan.<br>Ph. D.<br>Ph.D. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Chowdhury, Madhumita. "NiOx Based Resistive Random Access Memories." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1325535812.
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Parks, Jared D. "Hardware Authentication Enhancement of Resistive Random Access Memory Physical Unclonable Functions." Thesis, Northern Arizona University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10253956.
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<p> Advancements in microprocessors and sensor technologies have led to many innovations in the Internet of Things (IoT). These developments have both improved the quality of life for individuals and led to a need for securing users' information. This is especially true in devices such as pacemakers, cars, and credit cards, which can provide information that can harm users. To protect users from hackers who want this information, Physical Unclonable Functions (PUFs) can be used. Memory-based PUF are especially useful, as they can be readily implemented on most systems without much effort or additional hardware. This device is also unique in that it is very difficult to clone and hackers will have a hard time reading the contents of the device. Resistive Random Access Memory (ReRAM) PUFs in particular provide a similar manufacturing process to current Flash technologies, making them easily integrated into current technologies. On top of being similar to manufacture, ReRAM devices are also lower power than flash, allowing them to be used in low power devices such as Radio Frequency Identification Tags. While this is an advantage, ReRAM devices are currently limited in use since they vary greatly in different operating conditions. In this paper, a statistical model is proposed to account for shifts that occur at different temperatures. To generate the model, a mean square error linear regression analysis was performed, and found that these devices can be loosely represented as mean shifted Gaussian distributions at different temperatures. This model allows for a better understanding of how the system will perform during the challenge response pair authentication process. It was also found that the error rate can be reduced to near zero using this method, but may need improvement due to the limitations of this data-set. These limitations can be seen with the bit error rate, however these were improved using multi-state soft decoding. This process compared a ternary and eight state grouping, which allows for a better understanding of how each cell affects the array. Along with the statistical model the system will have minimal burden on the servers during the challenge response process, as it is computationally simple. Future works will include an implementation of this system to further allow ReRAM to become a more powerful technology, and help innovate the IoT.</p>
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Long, Branden Michael. "Fabrication and Characterization of HfO2 Based Resistive Random Access Memory Devices." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1365166054.
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Valverde, Lucas. "Conception de cellules bipolaires commutables pour la technologie « Resistive Random Access Memory »." Mémoire, Université de Sherbrooke, 2014. http://hdl.handle.net/11143/6041.
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Avec le développement des technologies portables, les mémoires de type flash sont de plus en plus utilisées. Les compétences requises pour répondre au marché florissant augmentent chaque année. Cependant, les technologies actuelles sont basées sur l’intégration de transistors. Leurs performances impliquent un long temps d’écriture et des tensions d’opérations importantes.
La technologie Resistive Random Access Memory (RRAM) permet de répondre aux problématiques liées aux mémoires de type flash. La simplicité de fabrication de ces mémoires permet une forte densité d’intégration à faible coût. Également, les performances attendues par cette technologie dépassent les performances actuelles de Dynamic Random Access Memory (DRAM).
Les études réalisées actuellement au sein de la communauté scientifique permettent de déterminer les meilleures performances selon le choix des matériaux. Les premières études se concentraient sur l’oxyde de titane TiO2 en tant qu’isolant, puis avec l’augmentation de l’intérêt envers cette technologie le nombre d’oxydes étudiés s’est élargi. Les dispositifs conventionnels utilisent une couche d’oxyde comprise entre deux électrodes métalliques. En augmentant la densité de dispositifs dans des circuits en matrices croisées, l’isolation entre les points mémoires n’est pas garantie et les courants de fuites deviennent un facteur limitant. Pour éviter ces problèmes, le contrôle de chaque cellule est réalisé par un transistor, on parle d’architecture 1T1R avec n transistors nécessaires pour n points mémoires.
En 2008 Dubuc[1] propose un nouveau procédé de fabrication: le procédé nanodamascène. En adaptant ce procédé, et en disposant deux cellules dos à dos, nous créons un composant qui ne nécessite plus de transistor de contrôle [2]. Cela permet, en outre, de réduire les courants de fuite et simplifie l’adressage de chaque cellule. Les dispositifs sont incorporés dans une couche offrant une surface planaire. Il n’y a pas de limite technique à la superposition des couches, ce qui permet une haute densité d’intégration dans le Back-end-of-line du CMOS (Complementary Metal Oxyde Semiconductor), offrant de nouveaux horizons à la technologie RRAM.
Suivant les éléments précédents, mon projet de maîtrise a pour objectif de démontrer la possibilité de fabriquer des cellules RRAM en utilisant le procédé nanodamascène. Ce développement implique la fabrication, pour la première fois, de dispositifs micrométriques de type croisés et planaires en utilisant des architectures dont la fabrication est maîtrisée au sein du laboratoire. Cela permettra de mettre au point les différentes procédés de fabrication pour les deux types de dispositifs, de se familiariser avec les techniques de caractérisation électrique, d’acquérir des connaissances sur les matériaux actifs, et proposer des premiers dispositifs RRAM.
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Zhuo, Yiqian Victor. "Resistive switching in tantalum oxide for emerging non-volatile memory applications." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648887.
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Cheng, You-Wei, and 鄭又瑋. "Oxide-Based Resistive Random Access Memory." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/52860599754950649604.
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碩士<br>國立交通大學<br>顯示科技研究所<br>98<br>In this thesis, we demonstrate inorganic resistive random access memory (RRAM) using sputtered SiO2 thin films, and investigate the influences of electrical characteristics
of the devices with various post-annealing conditions. The results show that devices with RTA treatment can exhibit better electrical characteristics, especially in the significant improvement of endurance. We also analyze carrier transport behaviors in the high conductance state of devices and propose carrier transport mechanisms under different RTA treatments.
In addition, we fabricate two different structures of organic RRAM: AlOx/Alq3 bi-layer and Alq3/MoO3/Alq3 tri-layer structures. It is found that interface defects at the
AlOx/Alq3 interface dominate the resistive switching of organic RRAM using the bi-layer structure, and the high ON/OFF current ratio near 106 is obtained; the switching behavior of organic RRAM using the tri-layer structure originate from carrier confinement barriers produced by the difference of energy bands between the nano-structure MoO3 and Alq3 layers, and this devices exhibit a high ON/OFF current ratio about 104 and provide many write-read-erase-read cycles.
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Chiu, I.-Chen, and 邱依宸. "Research of Transparent Resistive Random Access Memory." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/q5tdy2.
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Hsu, Meng-Yin, and 許孟尹. "Shallow Trench Isolation Sidewall edge Resistive Random Access Memory Integrated Nonvolatile Static Random Access Memory." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/k76znp.
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Chen, Yi-jiun, and 陳怡均. "Characterization of Amorphous Carbon Resistive Random Access Memory." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/5xr43a.
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博士<br>國立中山大學<br>機械與機電工程學系研究所<br>102<br>The increasing demand for flash memory densities by scaling dimension is a formidable challenge due to physical limitations. Recently, carbon-based resistive random access memory (RRAM) exhibits to be a promising candidate for high density and low power consumption. In this study, the resistive switching property of amorphous carbon material was investigated for RRAM application.
In this study, the amorphous carbon films were prepared by RF megetron sputtering and PECVD methods. The RRAM devices were constructed by an amorphous carbon layer between Pt top and TiN bottom electrodes. A bias was applied to the bottom electrode (TiN), and the top electrode (Pt) was grounded during the electrical measurement. Based on material characterization and electrical analysis, it is found that the switching of high and low resistive state (HRS and LRS) of sputtered carbon RRAM is attributed to hydrogenation and dehydrogenation reactions of C-C double bonds and hydrogen ions. After an electroformation, a sp2 carbon dominated filament was formed in the carbon layer. Appling a negative bias, hydrogen ions are attracted by electrical field and reacted with C-C conjugated double bonds, leading the transformation of conductive sp2 structure in to insulated sp3 structure. In contrast, hydrogen atoms in the sp3 structure are repelled into Pt electrode by a positive bias, which results the transformation of sp2 carbon. In addition, the experiment result of DLC RRAM also shows the same electron transport mechanism to the sputtered RRAM. Therefore, the resistance switching (RS) mechanism of amorphous carbon is concluded to hydrogen reacting with C-C double bonds.
Furthermore, the influences of Pt electrode and TiN electrode on the RS mechanism of amorphous carbon RRAM were investigated by two devices with HfO2 and DLC stacking, DLC-T RRAM (Pt/DLC/HfO2/TiN) and DLC-B RRAM (Pt/HfO2/DLC/TiN). By contrast, RS mechanism of DLC-T RRAM is similar to DLC RRAM. It demonstrates that the RS occurs in DLC layer near Pt electrode, which is consistent with the hydrogen induced RS model. Further, DLC-B RRAM is consistent to the RS model of graphine-oxide RRAM, that after a forming process, oxygen atoms in HfO2 are attracted by the positive electrical filed and then move to TiN electrode, in which oxygen ions absorb and eliminate with sp2 carbon (C-C conjugated double bonds), resulting to the RS in DLC-B RRAM.
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Hong, Yi-Siang, and 洪義翔. "Crystalline CuO Nanowire Based Resistive Random Access Memory." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/54332879744083613472.
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碩士<br>國立交通大學<br>材料科學與工程學系所<br>102<br>For the development of high density memory arrays of resistive random access memory (RRAM), nanowires provide the potential to reduce the device size to overcome the limitation of conventional lithography. In this work, copper oxide nanowires(NWs) were synthesized and served as the building block for 1-D RRAM nanodevice. The phase of Copper oxide was identified to be CuO by selected area electron diffraction (SAED) patterns and energy dispersive spectrometer (EDS). In addition, we fabricated the Au/Ti/CuO NW/Ti/Au RRAM nanodevices by electron-beam lithography system. The unipolar measurement demonstrated that the RESET process was resulted from Joule-heating effect. Also, the fitting result showed the conducting mechanism of LRS is space charge limited current(SCLC). From the HRTEM observation, we found the Cu2O phase generated from cathode to anode around the surface of nanowire, which result from the higher concentration of oxygen vacancies segregated at surface. The oxygen vacancies path contributed to the resistive switching behavior, which was confirmed by Electron Energy Loss Spectrum (EELS). Furthermore, we replaced the top electrode by silver which further enhanced the resistive switching properties. In this study, the switching mechanism was be confirmed by I-V measurement, HRTEM, and EELS. The result would be beneficial to improve the switching properties of nonvolatile memory device at nanoscale.
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Hsu, Kai-Hsiang, and 許凱翔. "SPICE Modeling for Bipolar Resistive Random-Access Memory." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/87398208717222433409.
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碩士<br>國立宜蘭大學<br>電子工程學系碩士班<br>101<br>Since its introduction in 1988 by Toshiba, NAND flash nonvolatile memory has undergone an unprecedented growth, becoming one of today’s technology drivers. Although NAND flash memory has scaled to 1x-nm feature size, shrinking cell sizes to reduce the number of electrons stored on the floating gate results in ultimate scaling challenges.
As the existing technology is facing severe challenges, in this thesis, we focus on exploring a new generation of memory devices, Resistive Random Access Memory (RRAM),and develop a compact SPICE model using Verilog-A. The resistance of a bipolar RRAM can be changed by applying forward and reverse biases, and such physical phenomenon must be accounted for in the model. We successfully simulate electrical conduction and heat transfer in the conductive filament, and propose an RC circuit to describe the time-dependent characteristic in reset process. As RRAM technology is emerging, our model can be used to design MLC memory circuits and improve the efficiency of programming strategies.
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Kao, Kung-Kai, and 高公鍇. "The Study on HfO2 Resistive Random Access Memory." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/67173071485578905086.
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碩士<br>國立清華大學<br>電子工程研究所<br>98<br>In recent year, non-volatile memory has become more and more important in our life. However, as the CMOS scaling goes on, we need faster, smaller, and less power consume’s memory to use in portable merchandises. Under this condition, resistive switching random access memory (RRAM) has strong potential among next generation non-volatile memory candidates. Hence, our study will focus on RRAM and its applications.Among so many RRAM materials, we decide using HfO2 to be our dielectric layer and Ti as top electrode TiN as bottom electrode. It is because HfO2 has been broadly used in COMS process and Ti, TiN also wieldy used in via as adhesion layer and stopping layer. So our material can directly compatible with CMOS process without any other contaminations issue.Our study can be divided to two parts: one is basic HfO2 RRAM characteristic the other is studying the possibility of HfO2 RRAM application in multi-level operations. Finally, by using changetemperature technique, we can abstract the defect levels , erase/programming times ,power consumptions and device operation behavior under different compliance current. Hoping our study will give other researchers help and contributions to RRAM.
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Mei, Chin Yu, and 梅晉瑜. "A Study of Novel Resistive Random Access Memory." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/62397841353791957521.
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碩士<br>國立清華大學<br>電子工程研究所<br>101<br>Recently, a kaleidoscope range of high-technology electronic products-including smart phone, tablet, and laptop- have long time hungered for an alternative for mass data storage application. The mainstream NVM that dominate the market nowadays, Flash, have suffered from a spectrum of challenges--current leakage, ultra-high apply voltage, and, most important, scale possibility. These barrier, paradoxically, serve as catalyst for full-bloom investigation on new memory technology, especially resistive random access memory, RRAM.
In this dissertation, we propose a novel embedded RRAM structure that is fabricated by advanced 28nm high-k metal gate (HKMG ) CMOS logic process.This memory cell is fully compatible with CMOS logic process without any extra process flow or mask. This RRAM owns small resistive switching area and unipolar characteristics, which ensure promising candidate of high density application like cross-point array. The DC analyses demonstrate the low voltage operation and high program speed, optimizing the set/reset supply voltage as well. The set/resetdisturb test, continuous read test and 150oC and 85oCbaking for 500 hours retention test, ultimately, prove highly endurance and no reliability concern which guarantee this memory cell as the candidate for next generation.
We, moreover, discuss the cell characteristics and structure along withthe characteristics of DC and AC analyses, reliability results and CMOS compatibility issue to fully understand the HKMG RRAM and to optimize the RRAM performance.
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黃建元. "A Contact Resistive Random Access Memory Based True Random Number Generator." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/85553721471604883853.
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碩士<br>國立清華大學<br>電子工程研究所<br>100<br>With the popularization of the Internet, data transmission has become more convenient and highly mobile. In order to prevent data theft, data encryption system is essential to modern communication chips. A stable and True Random Number Generator (TRNG) is a key element to ensure the security of transmitted data.
TRNG based on the trapping and de-trapping process in the oxide defects has been proposed in recent years. Generating random numbers using electron trapping has several advantages. First, as the source of this random process occurs naturally, hence the resulting random number is aperiodic. In addition, the output is generally insensitive to temperature. Random number generator circuits depend on random latching of inverter pair can subject to mismatch effects. In a MOSFET, random telegraph noise (RTN) refers to the drain current fluctuation (ID-RTN) as a result of the change in the amount of carriers flowing from source to drain. These RTN signals with discrete drain current levels is generally very small and can lead to misleading results after amplifications.
In this paper, we proposed a TRNG based on the RTN signals found in the contact resistive random access memory (CRRAM) device. As reported in previous studies, the resistance levels of both the high and low resistance states are subject to high RTN, leading to large read current noises as a results of electron trapping in the conductive pathway. These RTN signals from the embedded CRRAM cells is much larger than ID-RTN, which allows CRRAM to be more appropriate source for generating true random number for encryption circuitry.
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Prasad, Om, and Om Kumar Prasad. "Resistive Switching Characteristics of Co-doped ZnO Transparent Resistive Random Access Memory." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/84615410656940555687.
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碩士<br>國立交通大學<br>電機資訊國際學程<br>103<br>In this thesis, various Cobalt doped Zinc oxide (Co: ZnO) thin film as a resistive switching layer for transparent resistive switching random access memory (T-RRAM) devices was investigated. The influence of Co doping concentrations (0, 2 and 5 mol%) on structural and electrical properties of Co-doped ZnO T-RRAM have been studied. Co doped Zinc Oxide was synthesized using oxide mixing and calculation methods to fabricate sputter target. X-ray diffraction analysis indicated that the undoped and doped ZnO and Co: ZnO thin film has a hexagonal wurtzite structure with (002) preferential orientation crystalline nature. The maximum average crystallite size of Co: ZnO were 55.47 nm at a concentration of 2%, indicating that the crystallinity of doped powders were improved after doping. Approximately 38 nm thick of Co: ZnO films were deposited on the ITO / glass substrate using RF-magnetron suppter. ITO top electrode was deposited in order to fabricate sandwich structures. The optical transmittance exhibits that all undoped and doped devices are fully transparent (approximately 85% in the visible wavelength region) and demonstrate bipolar switching behavior. Resistive switching performance was enhanced after doping 2 mol% of Co. Good endurance of 4500 DC stable switching cycles with a resistance ratio of HRS/LRS about 20 times are achieved at a low operating voltage and data retention up to 104 sec in room temperature have achieved. The conduction mechanism of Co: ZnO RRAM was also discussed. These results indicate that Co: ZnO resistive layer is a promising candidate for the transparent resistive switching device. It has good potential for next generation non-volatile applications and as an embedded in transparent electronic devices.
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Ciou, Jian-Fa, and 邱健發. "Study on Diamond-Like Carbon Resistive Random Access Memory." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/r744cu.
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碩士<br>國立中山大學<br>機械與機電工程學系研究所<br>102<br>In recent study, C doped SiO2 was found as a dielectric layer exhibiting a very good RRAM performance. The resistive switching mechanism of C:SiO2 RRAM are different from the other kinds of metal oxide filament like device switching by oxygen ions. Therefore, this thesis applied PECVD DLC film as the dielectric layer to study the RRAM, to discuss its resistive switching characteristics. From the I-V fitting of DLC RRAM has found that comparing to C:SiO2 RRAM there are two new conduction mechanism of Frenkle-Poole emission in Low Resistance State and Schottky emission in High Resistance State. Since there is no oxygen ions existing in DLC film, the resistive switching mechanism of DLC RRAM should be different from which due to oxygen ions in metal oxides RRAM. In this thesis a hydrogen ions model is proposed to explain the resistive switching mechanism. For comparison, an additional experiment, in which a DLC RRAM is fabricated with adding hydrogen during sputtering Pt electrode to make extra more hydrogen ions deposited in Pt electrode. From IV analysis is found that the resistance of HRS increased significantly indicating that more hydrogen ions reacted with carbon induced higher-impedance state by more C-H bonds transformed from C=C bonds. Furthermore, a double-stacked RRAM structure of Pt/DLC/HfO2/TiN is fabricated to check this model. The I-V analysis shows that the resistive switching of RRAM takes place in DLC layer near Pt electrode, and it is suggested that the switching mechanism is due to the reaction of oxidation-reduction by hydrogen ions. While an opposite stack structure RRAM with Pt/HfO2/DLC/TiN reveals a resistive switching mechanism taking place near TiN electrode, and the switching mechanism is suggested the HRS due to the oxygen ions stretching the π bond between two carbon atoms causing the enlarging the length of π bond. From the experiments varying by temperature from 300~360 K, it is found that HRS resistance decreases as the temperature increases, This result shows a hydrogenating reaction occurred with endothermic reaction with the positive formation energy. On contrast, the Pt/HfO2/DLC/TiN RRAM shows an exothermic reaction with negative formation energy for the oxygen adsorption model of switching mechanism. From these experiments, the hydrogen model is consistent with the switching mechanism of DLC RRAM.
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Ke, Meng Hsuan, and 柯孟萱. "Improvement of HfO2-based Bipolar Resistive Random Access Memory." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/67113035360281105921.
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碩士<br>國立清華大學<br>電子工程研究所<br>102<br>The resistive RAM has advantages of simple structure, high density, fast switching speed, low power operation, and reliable retention. Furthermore, some RRAMs are friendly for CMOS integration. Thus, RRAM has a great potential as mainstream memories in the future.
In this thesis, TiN/Ti/HfO2/TiN RRAM structure was fabricated and studied. Thin Ti layer was inserted between top electrode and hafnium oxide, which can absorb oxygen atoms from dielectric layer. This Ti layer can greately enhance the performance of the RRAM by serving as an oxygen reservoir to fullfill the supply and demand of oxygen in HfO2 layer. The effects of four experiment structure and process parameters on the performance of RRAM were studied in this thesis: active region size、thickness of dielectric layer、annealing temperature、annealing time. The annealing temperature and time plays an ctitica role in this device fabrication.
The layer structure of Resistive RAM device studied in this thesis was TiN/Ti/HfO2/TiN, with Ti thickness of 10 nm and HfO2 thickness of 10 nm. By applying post metal annealing at 500⁰C for 4 minutes, RRAM with low operation voltage (<1V), reliable switching endurance (>10^6cycles), high ON/OFF ratio (>10^2) ,and good retention(>5×10^4s) can be achieved.
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Chan, Yi Chun, and 詹宜竣. "Gadolinium oxide based transparent resistive random access memory study." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/77715164221664958916.
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碩士<br>長庚大學<br>電子工程學系<br>98<br>In recent years, resistive random access memory has been widely researched, based on its low operation voltage、short write/erase time、long storage time、nondestructive readout、multi-bit storage and simple structure will be as a candidate for next generation nonvolatile memory. In this thesis, we use pulsed laser deposition to deposit the gadolinium oxide as our resistive layer, combining with the transparent electrode “ITO” to carry out the full transparent resistive random access memory. However, according to some literature, whether the resistive layer is polycrystalline or not will influence our resistive switching properties. In this thesis, we varied the substrate temperature as RT, 200oC, 300oC during depositing Gd2O3 films, with material instrument such as SEM, XRD, and TEM, we could analyze the properties of thin films. At last, we use semiconductor I-V instrument to measure the resistive switching of our device. The electrical device properties of this three different deposition temperature, the effects of compliance currents, and the operation voltages are also analyzed. In addition, we also measure the reliability of our device, the result shows an excellent retention time. According to the data we see, the endurance of ITO/ Gd2O3 (300oC)/ITO demonstrates more than 2000 times, which is related to whether crystalline of film or not. However, the resistive switching properties of unipolar are not good enough. Hence, we should still investigate the resistive switching of unipolar. Based on the further research, it is expected that TRRAM can be as the next generation memory.
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Wu, Che-Wei, and 吳哲維. "Low Voltage Operation Circuits for Resistive Random Access Memory." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/05177432460856435698.
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Huang, Jian-shiou, and 黃建修. "Material Exploration and Applications in Resistive Random Access Memory." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/86874690476378587023.
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博士<br>國立清華大學<br>材料科學工程學系<br>101<br>Fast-emerging next-generation nonvolatile memories include resistive random access memory (ReRAM), phase-change random access memory (PRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FeRAM). In this dissertation, our purpose were the development of new functional material and novel structure for ReRAM application, aiming to improve the memristive characteristics.
The first topic of this dissertation focuses on the electric induced resistive switching phenomena based on Cu-doped amorphous SiOx functional films (SCuO). Electrical switching of resistive memory is highly interface-dependent. We studied such a switching of Cu-doped amorphous SiOx thin-films in sandwich stacks Cu/SCuO/Pt. The stacks were prepared using radio frequency sputtering except Cu co-doping which utilized direct current (DC) power from 2 W to 15 W. We characterized electrical switching behavior by a Keithley 4200 semiconductor analyzer. Cu/SCuO/Pt devices with Cu-doping at DC-sputter 2 W exhibit the best switching performance showing reproducible forming-free and non-polar switching. The endurance is more than 102 cycles, electrical resistance ratio more than 10, and operating voltages as low as: ±0.75 V for SET and ±0.45 V for RESET. The switching mechanism of Cu/SCuO/Pt stacks is explained based on both filamentary conduction and diffusion of Cu ions/atoms in SiOx. Both ‘temperature coefficient of electrical resistance’ and ‘bonding status’ at different depth-profiles as analyzed by using X-ray photoelectron spectroscopy provide robust evidences of the mechanisms. Cu-doped amorphous SiOx thin-films are thus potential for resistive memory.
The second topic of this dissertation focuses on the electric induced resistive switching phenomena based on Zn-doped amorphous SiOx films, (SZO). We demonstrated dual resistive switching capability of SZO films. Both mono-stable selector-switching and bi-stable memristive switching are tuning via Zn-doping content and appropriate operation conditions. Voltages of selector-switching in Pt/SZO/ITO stacks can be noticeably modulated by varying Zn-doping. The selector-switching is stable for more than 100 cycles with a resistance ratio of 104 at voltages within +3 V. Stable memristive switching is obtainable by current-controlled RESET and voltage-controlled SET. We found that selector-switching arises from generalized trap-assisted tunneling of electrons provided by zinc addition. The dual-switching-mode of SZO is proposed to facilitate implementation of cross-bar RRAM.
The third topic of this dissertation, aims at developing a cost-effective method for ReRAM application. Cyclic voltammetry deposition (CV-D) was applied to deposit ZnO films on indium-tin-oxide (ITO) glass. The result is much superior coverage of the CV-D thin films as compared to those obtained by conventional electrochemical deposition. The Pt/CV-D ZnO/ITO devices in which ZnO prepared by CV-sweeping within ± 0.9 V for 6 cycles then fix-potential-deposited at - 0.75 V for 300 s show reproducible forming-free bipolar switching operation at voltages ≤ ±1 V. The cycle-life is at least 200 cycles. The electrical conduction belongs to space-charge-limited-current conduction mechanism, which is fitted to extract carrier mobility 0.97 cm2/Vs and carrier concentration 8.6x1018 cm-3. Gradient oxygen bonding status in ZnO film, typical of cyclic voltammetry deposition, was found to facilitate the electrical switching at low voltages.
In the fourth topic of this dissertation, is to work out a simplest ReRAM configuration based on single layer transparent conducting oxides (TCO). Bias-polarity-induced transformation of point contact resistive switching memory is demonstrated on three kinds of TCO layers, including tin-doped indium oxides (ITO), fluorine-doped tin oxides (FTO), and aluminum-doped zinc oxides (AZO) as conducting electrode as well as memristive material by the controllably electrical field simultaneously. Voltage-controlled SET and current-controlled RESET were utilized to obtain much more stable endurance results. The special RS behavior based on the TCO single layer provides a new material selection and the simplest geometry to realize the highest stacking density at development of three dimensional (3D) point-contact ReRAM application.
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Ho, Ying-Hao, and 何英豪. "The Resistive Switching Characteristics of Resistive Random Access Memory made with SiOx films." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/39143810495692342321.
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Ho, Jen-Yen, and 何任晏. "Influence of Transient Current of Resistive Switching onCharacteristics of Resistive Random Access Memory." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/49079731262447276907.
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碩士<br>國立高雄應用科技大學<br>電子工程系<br>99<br>The Pt/NiO/Pt device and the Cu/SiO2/Pt device were prepared to investigate the resistive switching behavior. The switching behavior of the Pt/NiO/Pt device was dominated by the filament model with a thermochemical reaction while that of the Cu/SiO2/Pt device was due to the filament model with an electrochemical reaction. Transient currents were observed during the forming and the SET process, which was due the discharge of the parasitic capacitors. The parasitic capacitance included the system capacitance and the device capacitance. A large transient current may cause hard breakdown or damage during the forming and the SET process. Therefore, a read resistance was adopted to monitor the transient current. The peak current decreased with a decrease of switching voltage or an increase of series resistance. A circuit model was also adopted to simulate the transient currents at several nodes. The transient currents were simulated with several element values to evaluate the influence of read resistance, load resistance, device capacitance, and device resistance on the peak current. In addition, several methods were proposed to decrease the peak current.
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Ming-YungYu and 游銘永. "Resistive Random Access Memory with ALD Aluminum Oxide Dielectric Layer." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/86225f.
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碩士<br>國立成功大學<br>微電子工程研究所<br>103<br>In this thesis, aluminum oxide thin film, deposited by an atomic layer deposition (ALD) system, is utilized as the dielectric film for the fabrication of resistive random access memory (RRAM) with a titanium (Ti) layer as the top electrodes and platinum (Pt) as the bottom electrodes. The RRAM with a metal-insulator-metal (MIM) structure of Ti/Al2O3/Pt is switched between the high resistance state (HRS; OFF state) and its low resistance state (LRS; ON state) by the external electrical stimulation. The HRS or LRS are probed by applying a low applied voltage across two counter electrodes and measuring its conduction current.
It is observed that the Ti/Al2O3/Pt structure shows good ON/OFF conduction current ratio 〉103 with measured, retention time 〉104 s and switching cycles 〉10 times. The trap-controlled space charge limit current (SCLC) might have dominated the conduction current of the HRS while the conduction current of the LRS might be dominated by the Ohmic conduction.
Al2O3 is known as a high-k material, with a dielectric constant k=10, a large energy band gap (9 eV), high breakdown strength (5-10 MV cm-1) and has good thermal and chemical stability. When oxygen ions migrate to the top electrode by external electrical stimulation, the conductive filamentary channel composed of oxygen vacancy is stable in the Al2O3 thin film. Therefore, Al2O3 and some other binary metal oxide thin films are suitable dielectric materials for RRAM.
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CHEN, WEI-JHOU, and 陳韋州. "Characteristics of Polyvinylpyrrolidone Doped ZnO Nanorods Resistive Random Access Memory." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/g738n6.
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碩士<br>修平科技大學<br>電機工程碩士班<br>105<br>The first ,ZnO thin film were prepared on flexible stainless steel (FSS) substrates by means of sol-gel method and spin coating technology followed by rapid thermal annealing treatment(RTA). After, adopt an approach of hydrothermal growth Polyvinylpyrrolidone doped ZnO nanorods and growth ZnO nanorods. And then spin-coated a layer of insulating layer on the nanorods. Finally, use of Thermal Evaporation Deposition of electrode so that the formation of random access memory MIM structure.
The resulting ZnO nanorods and PVP doped ZnO nanorods random access memory devices were found to exhibit bipolar resistive switching characteristics. Switching between high resistance state (HRS) and low resistance state (LRS) could be achieved at a very low threshold voltage of 1.46 V and1.48 V for a long conducting channel of 500 nm exhibiting a very low electric field PVP is shown to be faster than the undoped PVP the current is relatively high. The results indicate the application potentials of the doped PVP zinc oxide nanorods is better than that of the undoped PVP zinc oxide nanorods and the resistance ratio is also higher. Has the potential to become the next generation of nonvolatile memory.
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Feng, Li-Wei, and 馮立偉. "Fabrication and Characterization of FeOx Based Resistive Random Access Memory." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/35187264706058711755.
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博士<br>國立交通大學<br>電子研究所<br>99<br>With the arrival of Digital Age, nonvolatile memory (NVM) plays an important role in portable electronic products, such as the mobile phone, digital camera, and notebook computer. Floating gate composed nonvolatile memories have been widely applied in electronic devices in recent years, but it has many drawbacks, including high operation voltage, low operation speed, and poor endurance. Moreover, as the device dimensions are continuously scaled down, the floating gate composed memory faces the challenge of thin tunneling oxide that causes an unsatisfactory retention time. Consequently, resistive random access memory (RRAM) is one promising candidate to substitute for conventional floating gate memory. As for RRAM, the digital data can be stored in two memory states with high and low resistivities, ON-state and OFF-state, respectively. The two memory states can be easily switched by voltage biases or pulses, which enhance the possibility of the application in circuit level. Therefore, the topic of this thesis discusses this advanced nonvolatile memory devices by fabricating and characterizing iron-based RRAM devices and, furthermore, proposes the methods to improve the characteristics of the proposed devices for NVM applications. The proposed iron-based RRAM device was fabricated by a structure of TiN/SiO2/FeOx/Fe, where the FeOx is a thin transition layer at the SiO2/Fe interface and produced spontaneously during the plasma-enhanced tetraethyl orthosilicate oxide deposition process due to the ease of oxidation of iron atoms. The basic idea of the proposed structure is that the resistive switching effect is associated with the existence of nonstoichiometric materials, so the thin FeOx transition layer produced by partially oxidizing the iron electrode surface exhibits a richer nonstoichiometry property because of containing the compositions varied from Fe-rich FeOx (close to Fe electrode) to oxygen-rich FeOx (close to SiO2 layer). Moreover, in order to clarify the detailed mechanism of resistive switching effects, a method of adding platinum (Pt) into Fe electrode, which affects oxidation and diffusion characteristics of Fe layer, was also proposed by a TiN/SiO2/FeOx/FePt structure. In addition, observation of bubble effects occurred at the top electrode after biasing highly opposite polarity voltage stresses as well as the electrode area dependence of resistance values also provides another indirect method to clarify the mechanism of resistive switching effects.
Moreover, the influence of thermal annealing treatments on the FeOx resistance switching behaviors was also researched because of the thermal sensitivity of the iron oxide layer. The distinct reduction of memory switching parameters in forming voltage, set/reset voltages, and even their dispersions was obtained after annealing. The cause was also discussed by XPS, TEM, and XRD analyses. Additionally, statistical electrical results, including set/reset current, set/reset voltage and set/reset power, also help for understanding the mechanism of resistive switching effects.
Furthrmore, multiple resistance states were easily observed to obtain in our proposed FeOx-contained structure by justifying the sweeping voltage during the reset process region and the compliance current during the set process region, which allow more bits to be stored per cell for application. Moreover, extraction of statistical results, such as set/reset voltage, set/reset current and set/reset power, further provides more details to clarify the mechanism of the FeOx-contained resistive switching behaviors.In the final part of this dissertation, the conclusions and the suggested future works are presented.
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Hsia, Kuo-Yi, and 夏國譯. "Development of Three-Dimensional Vertical Resistive-Switching Random Access Memory." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/48705960735646915595.
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碩士<br>國立交通大學<br>電子研究所<br>101<br>In this thesis, the vertical structure with hafnium oxide and amorphous silicon resistive switching layers were prepared and studied. There are three main studies in this thesis. First, Ni/a-Si/n+ poly Si crossbar devices show a uniform set/reset voltage distribution due to corner effect. The second part is the results and discussion of vertical RRAM. In third part, we fabricate and analysis of the bilayer vertical RRAM.
From the electrical measurements of vertical RRAM, we find that HRS/LRS ratio are stable over 1 order. Retention test showed that our samples could remain 104s without degradation at 25℃ and 125℃. In addition, the bilayer vertical RRAM cells are compatible with 2 bits operation.
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Chang, Min-Ku, and 張銘庫. "Performance and Characteristics of LaAlO3-based Resistive Random Access Memory." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/99764578676213710377.
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碩士<br>中華大學<br>電機工程學系碩士班<br>102<br>The mainstream of non-volatile NAND flash memory will encounter a serious bottleneck when the feature size is down to 16 nm. Now the major manufacturers turn to 3D device or resistive random access memory (RRAM) which has more latent capacity. Both of them are bound to become the emphases for development of the next generation. The resistive random access memory (RRAM) caused considerable attention due to the characteristics of low-power consumption, low-cost productivity, high-speed operation, high-density integration and high-reliability device. However, the switching mechanisms of RRAM are not clear yet.
In this study, we used Lanthanum Aluminate (LaAlO3) as the main structure, and optimized the condition through the modulation of different thickness and different metals. There are three main parts of this paper. The first part used TaN/LaAlO3/TaN as the main structure. We studied the characteristics of RRAM through the modulation of the LaAlO3 thickness from 5 nm, 10 nm, 20 nm, and 30 nm by as-deposited, and different annealing conditions under 300℃, 400℃ and unannealing. The second part is different the thickness of Ti/LaAlO3/Ti from 20 nm, 30 nm and follow by the same annealing conditions. The third part is different the thickness of Al/LaAlO3/Al from 20 nm, 30 nm and follow by the same annealing conditions.
The Al/LaAlO3/Al devices exhibited excellent memory performances, including low operation current, low switching voltage (set/reset, -1.35/0.95 V), multi-bit storage characteristics, reproducible resistive switching, and reliable data retention at 100℃. The LaAlO3 RRAM shows the bipolar resistive switching property.
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Chen, Chan-Cheng, and 陳展承. "Electrical properties of NiO bipolar Resistive Random Access Memory (RRAM)." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/02010823156764631397.
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碩士<br>國立臺灣大學<br>物理研究所<br>100<br>In this thesis, a resistive random-access memory was fabricated by using the nickel oxide, grown by thermal evaporation followed by an annealing process at different temperatures, as the dielectric layer sandwiched between the p-type silicon substrate and the aluminum contact. Atomic force microscopy and X-ray diffraction analysis were carried out for the investigation on the surface morphology and the crystalline structure of the grown nickel oxide, respectively.
It was revealed that the annealing temperature and the oxygen flow were crucial to the electrical property of the nickel oxide layer. From the experimental results, it was found that the values of high-resistive and low-resistive states will increase with the incremental annealing temperature but decrease with the increasing oxygen flow rate at the optimized annealing temperature.
It was also observed that the surface morphology is the key factor for stabilizing the operation of the resistive random-access memory. The results indicated that a nickel oxide film with a rougher surface morphology will greatly improve the lifetime and the reliability of the device.
Resistive random-access memory is presently a developing subject for solid state devices and aimed to replace dynamic random-access memory and flash memory. The results in this thesis indicate that the stability and persistence of the resistive random-access memory devices will be the fundamental challenges for its future development.
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Chang, Huan-Lin, and 張環麟. "Physical Mechanisms and SPICE Modeling of Resistive Random Access Memory." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/35930855196141283758.
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博士<br>國立臺灣大學<br>電子工程學研究所<br>99<br>In this dissertation, SPICE models of phase change random access memory (PCM) and resistive random access memory (RRAM) are developed. The physical mechanism of RRAM is studied in particular in Chapter 4. Two appendixes are included for crosstalk reduction of dual PAs using laser treatment and EUV degradation study of SiGe heterojunction bipolar transistors.
In Chapter 2, the improved SPICE macromodel of the PCM solves critical prob-lems in the phase change circuit to produce accurate I-V curve with clearly modeled snapback behavior. The R-I curve is also in good agreement with the measured data. In Chapter 3, the compact SPICE model of PCM using Verilog-A accurately describes the I-V curve and provides a fundamental model R-I curve for quick verification of a large memory array with peripheral circuits. The advanced model R-I curve shows improved accuracy as it addresses the gradual resistance transition.
In Chapter 4, the thickness of Ti layer should be carefully designed because it de-termines the maximum amount of the oxygen vacancies to be generated in RRAM. In Chapter 5, SPICE model plays a bridging role between device fabrication and circuit implementation in any mature technology. In this chapter, we have demonstrated the making of a parameterized SPICE model for RRAM using subcircuit method. For future scaling of the RRAM, it is critical to understand the physics behind the switching phenomenon and put it into the SPICE model. In Chapter 6, we use the programming language of Verilog-A to develop a compact SPICE model of RRAM for memory circuit design. A two-level switching RRAM model is achieved with nine SPICE parameters. Verification of the proposed model are first done in 2x2 array and then by 1 kbit array with memory peripheral circuits.
Appendix A: A cost-effective isolation technique using laser treatment is proposed to suppress the undesired crosstalk between dual power amplifiers (PAs). Laser treat-ment not only reduces the small signal coupling between dual PAs but also enhances the linearity of the PA under dual-PA operation mode.
Appendix B: The effects of extreme ultraviolet (EUV) radiation on SiGe hetero-junction bipolar transistors (HBTs) are studied for the first time. The post-EUV base current increase is due to enhanced hole recombination by EUV-induced genera-tion-recombination traps in the depletion region.
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Shih, Yi-Hong, and 施怡宏. "A Novel FinFET Logic Compatible Via Resistive Random Access Memory." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/su2rfm.
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LIN, YU-SHENG, and 林裕勝. "Study of Copper Oxide-based Resistive Random Access Memory Devices." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/u3z6q9.
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碩士<br>國立雲林科技大學<br>電子工程系<br>107<br>In this study, copper oxide films were deposited using radio frequency magnetron sputtering as resistive switching active layers. This thesis is divided into two parts. First, top electrode dependence of the resistive switching characteristics of the CuO-based RRAM devices was investigated. The results indicate that the conduction filaments of the Al/CuO/ITO RRAM device are composed of copper cations. The resistive switching behavior could be significantly improved because of the spontaneous formation of an AlxOy interfacial layer between the Al/CuO interface. The 300 °C-annealed Al/CuO/ITO RRAM device exhibits a resistive window of ~10^3. Second, to obtain the optimal CuO resistive switching layer, the as-fabricated CuO layers were annealed in ambient at temperatures of 250 °C, 300 °C, 350 °C, and 400 °C. The results show that the resistive switching characteristics of the 350 °C-annealed Al/CuO/ITO RRAM device was significantly improved. The resistive window was enlarged to 10^5.
The surface morphology and the thickness of the CuO films were studied by using field emission scanning electron microscope (SEM). Ultraviolet-visible spectroscopy was used to obtain the transmittances and optical bandgaps of the CuO films. The chemical composition of the CuO films were characterized by using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The crystallinities of the CuO films were examined by X-ray diffraction (XRD). The electrical characteristics of the Al/CuO/ITO RRAM devices were measured using a Keysight B1500A semiconductor device analyzer.
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Chu, Chun-An, and 朱俊安. "HfOx-based Resistive Random Access Memory for neuromorphic computing application." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/ccvue3.
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碩士<br>國立交通大學<br>電子研究所<br>107<br>Due to that the device toward more powerful, Artificial Intelligence (AI) computing become more and more popular. Neuromorphic computing is one of the most popular model of AI computing. By simulating the weight update of synapses between the neuro cells when the human brain accepts outside signal, we can use a new way to update the hardware condition instead of software. It is expected that the AI computing become much faster and much lower power consumption.
According to oxygen vacancy rich layer model and low oxygen vacancy mobility model, we add AlOx layer between TiOx and HfOx for improving the device’s performance. Based on TEM and EDX analyses, we find that Al doped into HfOx layer to form HfAlOx compound film. Based on such the oxygen vacancy mobility of HfAlOx layer formation, would lead to narrow the second filament. Through experiments, 1nm thick AlOx layer employed in the TiN/TiO/HfAlOx/TiN device exhibits the best property. Such device obtains excellent properties such as faster speed device (both set and reset pulse width is 1us) with good nonlinearity (3.39 for potentiation and 2.87 for depression behavior) and best nonlinearity (2.15 for potentiation and 1.52 for depression behavior with 10us pulse width) with 500 conductance states and retention with more than 104 s.
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Murali, Santosh. "Investigation of bipolar resistive switching in zinc-tin-oxide for resistive random access memory." Thesis, 2011. http://hdl.handle.net/1957/26622.
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Resistive random access memory (RRAM) is a non-volatile memory technology based on resistive switching in a dielectric or semiconductor sandwiched between two different metals. Also known as memristors, these devices are potential candidates for a next-generation replacement for flash memory. In this thesis, bipolar resistive switching is reported for the first time in solution-deposited zinc-tin-oxide (ZTO). The impact of the compliance current on device operation, including the SET and RESET voltages, pre-SET, RESET and post-RESET currents, the resistance ratio between the low and high resistance states, retention, and the endurance, is investigated for an isolated Al dot/ZTO/Ir blanket device and for Al/ZTO/Pt crossbar RRAM devices. A gradual forming process is devised to improve device stability and performance. It is found that the device performance depends critically on the compliance current density that is used to limit the breakdown conduction during the SET operation. In addition, it was found that the conduction and switching mechanisms are consistent with the filament model of formation and rupture of conductive filaments.<br>Graduation date: 2012
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MEKALA, BHOOLAXMI, and 朴美佳. "Resistive Switching Characteristics of Multi-level Resistive Random Access Memory with ZrO2 buffer layer." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/gzb2a7.
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碩士<br>國立交通大學<br>電機資訊國際學程<br>105<br>Non-volatile memory technology plays a significant role in the market of electronics
products. It is widely used in mobile phone, digital camera, portal storage devices, MP3
players and so on. Currently, flash memories dominating the nonvolatile memories due to
their key properties. However, the data is stored by injecting the charge carriers in floating
gate. This will results degradation of oxide, so it encounter a serious technical challenge while
scaling down of the oxide thickness. Therefore, it is essential to find the scalability, viable
alternatives for this memory. Several non-volatile memories based on different concepts have
aroused such as Magnetoresistive RAM (MRAM), Phase change RAM (PRAM) and
Resistive RAM (RRAM). Compared with other types, RRAM shows relatively high speed,
simple structure and the lowest power consumption. Therefore, RRAM are potential
candidates for future conventional non-volatile memory to overcome the physical and
technological limitations.
The RRAM has a simple structure metal/insulator/metal (MIM) structure. These nano
devices are nonvolatile, and can store data in form of both low resistance state (LRS) and high
resistance state (HRS) in nanoseconds. The other incentives are its low operating voltage,
high endurance and integration in crossbar arrays.
In this thesis, the I-V switching characteristics of the ZrO2 based RRAM devices are
investigated and compared to the performance of similar devices from the literature in order
to confirm process viability. The Ni/ZrO2/TaN RRAM devices have synthesized and bipolar
switching observed. This RRAM device can be set from high- to low-resistance state (HRS to
LRS) with power consumption 5.19μW (reset power 7.70μW and set power 40.43μW) as
compliance current is 1mA and set voltage is 3V. Multi-level resistance states have realized
with power consumption of 0.128mW, 30.75μW and 50.19μW for level1, level2 and level3
respectively. Multi level resistance states have examined at different temperatures 25˚C, 50˚C,
75˚C and 100˚C. As temperature increases, the LRS and HRS increases and results into more
power consumption due to leakage current. Moreover, good endurance and retention
characteristic have achieved. Good electrical endurance characteristics has obtained up to 125
switching cycles, and good retention with a small HRS/LRS decay for 104 sec has measured
at 85˚C. Device to device uniformity and resistance window have significantly improved as
compared with the devices from the literature.
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CHEN, TZU-HSIANG, and 陳子翔. "Polarization Characteristics and Resistive Switching Mechanism of Molybdenum Oxide Resistive Random Access Memory Devices." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/bxjxjz.
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碩士<br>國立雲林科技大學<br>電子工程系<br>107<br>In this thesis, the polarization characteristics of sol-gel MoO<sub>3</sub> semiconductors have been investigated. The dipoles in the bulk MoO<sub>3</sub> are turned to form a built-in electric field, which is opposite to the applied electric field. The I-V characteristic reveals that the negative differential resistance (NDR) effect occurs at -1.2 V in the negative bias region and about at 1 V in the positive bias region where the built-in electric field is equal to the applied electric field. However, the electrical characteristics obtained from different scanning directions are different due to the presence of built-in electric fields. The memory windows (R<sub>HRS</sub>/R<sub>LRS</sub>) of the device are approximately 10<sup>2</sup>. Also, stability testing indicates that the memory can be repetitively operated over 5 x 10<sup>2</sup> cycles.
The electrical characteristics of the MoO<sub>3</sub>/ITO were measured using a tungsten probe contact along with a Keysight B1500A. The voltage cycles were applied to the tungsten contact, while the ITO electrode was grounded. The chemical structure and crystallinity of the MoO<sub>3</sub> thin film were characterized by X-ray photoelectron spectroscopy (XPS). The variation of the content of Mo<sup>6+</sup> and Mo<sup>5+</sup> in the bulk MoO<sub>3</sub> was analyzed. The crystallinity was investigated by X-ray diffraction (XRD), and it was found that the crystal structure of MoO<sub>3</sub> thin film changed from amorphous to the hexagonal structure after the annealing process. Field-emission scanning electron microscopy (FE-SEM) was used to observe the surface morphology and the thickness of the MoO<sub>3</sub> thin films. The analyses mentioned above can evidence the proposed resistive switching and carrier conduction mechanism of the MoO<sub>3</sub> RRAM.
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Chung, Yueh-Ting, and 鍾岳庭. "Traps Induced Reliability Issues in Resistive Random Access Memory and SONOS Flash Memory." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/00401619937660067709.
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博士<br>國立交通大學<br>電子工程學系 電子研究所<br>104<br>This dissertation will focus on major reliability issues in random access memory (RRAM) and SONOS flash memory induced by traps in a dielectric. Statistical characterization of SET-disturb failure time in an RRAM crossbar array, random telegraph noise (RTN) and single program charge induced Vt retention loss in SONOS are performed. Monte-Carlo simulation model and numerical simulation model are also developed to corroborate our characterization results.
In Chapter 1, first, the evolution of the nonvolatile memory technology in recent years and the major reliability concerns are addressed. Second, the applications and the reliability issues of an RRAM crossbar array will be demonstrated. Also, the impact of single charge phenomenon in SONOS flash memory will be pointed out. The organization of this dissertation will be given in this chapter.
In Chapter 2, a new degradation mode with respect to write-disturb failure time due to SET/RESET cycling in a tungsten oxide resistive random access memory is reported. In a crossbar array memory, we find that a write-disturb failure time in high resistance state reduces suddenly by several orders of magnitude after certain SET/RESET cycles. Although a memory window still remains after the degradation, the occurrence probability of over-SET state increases significantly. To investigate this new degradation mode, we perform constant voltage stress in HRS to characterize trap generation in a switching dielectric by measuring a stress-induced leakage current and low-frequency noise. The constant voltage stress is to emulate high-field stress and thus trap creation in SET/RESET cycling. We find that a low-field current in HRS via trap-assisted tunneling in a rupture region increases gradually in both constant voltage stress and SET/RESET cycling stress. The high-field stress-generated traps, unlike SET-induced oxygen vacancies, cannot be annihilated by RESET operation and are held responsible for a RESET endurance failure. A three dimensional Monte Carlo model based on a percolation concept of oxide breakdown is developed to simulate a SET-disturb failure time. Our model includes both stress-generated traps and SET-disturb induced oxygen vacancies. The model can well explain observed abrupt and drastic SET-disturb lifetime degradation, which is attributed to the formation of a conductive percolation path of stress-generated traps.
In Chapter 3, two more factors affecting SET-disturb failure time (f) including resistance window in operation and SET-disturb voltage are investigated. The dependence of f on resistance window in operation is characterized. We find that f is greatly affected by the current level of LRS. The strong LRS dependence of f is attributed to a small Weibull slope of f. In addition, we perform statistical characterizations of f at different SET-disturb voltages. A relationship between f and a SET-disturb voltage in a stressed cell is given.
Statistical characterization of two-level random telegraph noise (RTN) amplitude distribution in a hafnium oxide resistive memory has been performed in Chapter 4. We find that two-level RTN in HRS exhibits a large amplitude distribution tail, as compared to LRS. To investigate an RTN trap position in a hafnium oxide film, we measure the dependence of electron capture and emission times of RTN on applied read voltage. A correlation between an RTN trap position and RTN amplitude is found. Owing to a non-uniform distribution of oxygen vacancy after a RESET process, RTN traps near the cathode are responsible for an RTN large-amplitude tail in HRS mostly.
In Chapter 5, a Vt retention distribution tail in a Multi-Time-Program (MTP) SONOS memory is investigated. We characterize a single program charge loss induced Vt in NOR-type multi-level SONOS cells (MLC). Our measurement shows that (i) a single charge loss induced Vt exhibits an exponential distribution in magnitudes, which is attributed to a random program charge induced current path percolation effect and (ii) the standard deviation of the exponential distribution depends on a program charge density and increases with a program Vt level in a MLC SONOS. In addition, we measure a Vt retention distribution in a 512Mb MTP SONOS memory and observe a significant Vt retention tail. A numerical Vt retention distribution model including the percolation effect and a Poisson distribution based multiple charge loss model is developed. Our model agrees with the measured Vt retention distribution in a 512Mb SONOS well. The observed Vt tail is realized mainly due to the percolation effect.
Finally, conclusions are made and future work is described in Chapter 6.
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Huang, Yu-Chih, and 黃昱智. "Study on the Copper-Based Resistive Random-Access-Memory (RRAM) Devices." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/538d89.
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博士<br>國立交通大學<br>電子工程學系 電子研究所<br>102<br>In this thesis, five methods to enhance the resistive switching characteristic of metallic conductive types RRAM have been proposed, including pyramid-structured copper active electrodes, oxidized copper active electrodes, Cu-Ti alloy active electrodes, oxidized Cu-Ti alloy active electrodes, and Cu-doped TiO2 resistive switching layers with inert electrodes.
The pyramid structure fabricated with the potassium hydroxide (KOH) anisotropically etched (100) silicon substrate has been deposited with a copper film as the bottom electrode of the programmable metallization cell (PMC) memory to significantly improve the resistive switching characteristics. As compared with the conventional flat copper electrode, this pyramid-structured electrode exhibited the set/reset voltage as low as 1/0.6 V and superior endurance of 2400 cycles at the set/reset voltages of −5/+3 V for the voltages pulsewidth of 1 μs. The high performance of this PMC could be attributed to high local electrical fields at the tips of the pyramid structure, resulting in the formation of the narrower conductive filaments that facilitate the lower operation voltage and better endurance.
In order to reduce the copper content in the resistive switching layers, the RRAM cells with the oxidized copper has been deposited as the electrode. The sample possessed the better stability and larger memory window as compared to the conventional non-oxidized copper electrode ones. It was conjectured that the diluted copper atomic concentrations of the oxidized copper electrodes were favorable to reduce the excess residual copper atoms in the TiO2 layers. Therefore, the oxidized copper electrode samples could exhibited the lower OFF-state current with the larger on/off state current ratio (memory window) of 3 orders (103) and the better endurance as high as 1000 cycles than the conventional non-oxidation copper electrode ones of 1.7 orders and 400 cycles.
Furthermore, the programmable metallization cell (PMC) memory devices with Cu-Ti alloy films as the bottom electrodes have been shown to exhibit a larger memory window of 2.3 orders and better endurance of 1000 cycles as compared to the conventional pure copper electrode ones. It was conjectured that the Cu-Ti alloy electrodes could obtain the appropriate amount of copper atoms to format and rupture the conductive filaments in the resistive switching layer.
Moreover, the devices with oxidized Cu-Ti alloy bottom electrodes have been also shown to achieve the a superior memory windo as high as 3 orders and endurance of 3000 cycles as compared to conventional pure copper and non-oxidized Cu-Ti alloy electrodes ones. It was conjectured that the oxidized Cu-Ti alloys could control the Cu cations from the Cu and Cu2O to the appropriate amount to achieve the most favorable resistive switching characteristics.
In addition, the resistive RRAM cells with Cu-doped TiO2 film between two Pt inert electrodes were produced in this work, and these devices could achieve a lower required programming voltage of –0.7 V and higher endurance of about 1000 cycles at the programming/erasing voltage of –5 V/+3 V for the pulse width of 1 μs, as compared with the conventional Pt/TiO2/Cu ones. It was conjectured that the distribution of Cu sources in the Cu-doped TiO2 (TiO2 : Cu) resistive switching film facilitated the formation of sharp and narrow conductive filaments since the Cu sources were redox more easily to form the filaments. The proposed Pt/TiO2:Cu/Pt sample could thus achieve a lower DC programming voltage than the conventional one. Moreover, it was conjectured that the better endurance of the Pt/TiO2:Cu/Pt sample was due to the lower amount of residual Cu atoms in the TiO2 layer from the ruptured narrower filaments during the erasing process. This was because the increase in the amount of Cu atoms was limited by the inert Pt electrode when there were uniformly distributed Cu sources and there was no Cu electrode.
Finally, the summary and conclusions as well as the future prospects for the further research were also proposed.
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Lin, Wen Zhang, and 林文章. "A Reliability-aware Write Termination Scheme for Resistive Random Access Memory." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/3k59pp.
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Huang, Yi-Jen, and 黃義仁. "Architectures design and characterization of low power resistive random access memory." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/qfr7y7.
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博士<br>國立臺灣大學<br>電子工程學研究所<br>105<br>Recently, the rapid development of nonvolatile memory technology has enabled a great revolution of digital technology including mobile phone, display panel, USB flash drivers, digital cameras and computer. However, the charge-based flash memories will face formidable device scaling challenges. In order to have more compatible storage devices for future electronic device applications, resistive random access memory (RRAM) is the most promising candidate to replace the charge-based flash memories due to its advantages, such as high-speed operation, low power consumption, high endurance, and CMOS compatible. More importantly, the simple structure of RRAM makes it feasible to be integrated into the 3D horizontal (3D-HRAM) and vertical (3D-VRAM) cross-point arrays to realize the high storage density. Nonetheless, RRAM technology has not yet begun to replace the mainstream flash technology which is mainly delayed by programing power consumption, small memory window, poor reliability and serious sneak current problems in the crossbar memory arrays. Therefore, the objective of the research is to improve the performance of the RRAM devices by several reliable designs as below.
1. Dual-functional Memory and Threshold Resistive Switching Based on the Push-Pull Mechanism of Oxygen Ions
The combination of nonvolatile memory switching and volatile threshold switching functions of transition metal oxides in crossbar memory arrays is of great potential for replacing charge-based flash memory in very-large-scale integration. Here, the resistive switching material structure, (amorphous TiOx)/(Ag nanoparticles)/(polycrystalline TiOx), fabricated on the textured-FTO substrate with ITO as the top electrode exhibits both the memory switching and threshold switching functions. When the device is used for resistive switching, it is forming-free for resistive memory applications with low operation voltage (<±1V) and self-compliance to current up to 50 μA. Therefore, the operation voltage and current are significantly reduced. When it is used for threshold switching, the low threshold current (-Ith = -2 μA and Ith = 0.1 μA, at -Vth = -0.8 V and Vth = 0.4 V) is beneficial for improving the sneak current problem in crossbar memory arrays.
2. Low-Power Resistive Random Access Memory by Confining the Formation of Conducting Filaments
In order to further improve the power consumption, memory window, uniformity and reliability of RRAM device in section 1, a resistive switching material structure, TiOx/silver nanoparticles/TiOx/AlTiOx, fabricated between the fluorine-doped tin oxidebottom electrode and the indium tin oxide top electrode is demonstrated. The device exhibits excellent memory performances, such as low operation voltage (<±1 V), low operation power (Pset = ~10 μW and Preset = ~0.65μW), small variation in resistance (The relative fluctuations of HRS and LRS are 3.5% and 7.6%), reliable data retention, and a large memory window (~300). The stable bottom AlTiOx barrier layer in the device structure limits the formation of conducting filaments; therefore, the current and power consumption of device operation are significantly reduced.
3. Graphene/h-BN Heterostructures for Vertical Architecture of RRAM Design
Because the 3D-HRAM requires critical lithography and other process for every stacked layer, and this fabrication cost overhead increases linearly with the number of stacks. Here, it is demonstrated that the 2D materials-based vertical RRAM structure composed of graphene plane electrode/multilayer h-BN insulating dielectric stacked layers, AlOx/TiOx resistive switching layer and ITO pillar electrode exhibits reliable device performance including forming-free, low power consumption (Pset = ~2 μW and Preset = ~0.2 μW), and large memory window (> 300). Owing to the ultrathin-insulating dielectric layer (~2 nm) and naturally high thermal conductivity characteristics of h-BN, the proposed vertical RRAM exhibits huge potential for future ultra high-density memory integration and per-bit lithography cost reduction by increasing the stacked layers.
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梁凱迪. "Synthesis and Characterization of Single CuOx Nanowire Resistive Random Access Memory." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/01285241540291707857.
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Tsai, Yu-Ting, and 蔡侑廷. "Fabrication and Electrical Characterization of Advanced Resistive Random Access Memory Devices." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/88164418384807083016.
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博士<br>國立交通大學<br>電子研究所<br>100<br>In conventional memory devices, poly-silicon is used as the “floating-gate” to store charge. However, the conventional floating-gate non-volatile memory device has faced the challenge of reliability due to the requirement of down-scaling device. The scaled tunneling oxide is difficult to prevent the stored charge in the floating-gate from tunneling back into the Si-substrate. To improve the retention time of conventional floating-gate memories, several novel memory devices have been proposed. The resistive switching random access memories (RRAMs) have advantages of low power consumption, high-density integration, and high speed operation as one of the next-generation nonvolatile memory candidates.
In the thesis, the influence of top electrode material on the resistive switching properties of MnO2-based memory film using Pt as a bottom electrode was investigated. In comparison with Pt/ MnO2/Pt and Al/ MnO2/Pt devices, the Ti/ MnO2/Pt device exhibits resistive switching current–voltage (I–V ) curve, which can be traced and reproduced more than 105 times only showing a little decrease of resistance ratio between high and low resistance states. Furthermore, transmission electron microscopy analyses are used to confirm the crystalline structure of MnO2 on Pt bottom electrode. Secondary ion mass spectrometry reveals a change of oxygen distribution in MnO2 thin film due to material characteristic of variant top electrodes. We suggest that the interface between MnO2 and electrodes play an important role on the resistive switching behaviors.
Then, we use the above mentioned optimize electrode composition on the DyMn2O resistive switching memory device. A negative differential resistance (NDR) phenomenon was first found at the forming process and resistive switching I-V curve. By applying approach voltage, dual resistive switching characteristics can coexist in on memory device. The typical switching effect could be attributed to the formation and rupture of the conducting filament in DyMn2O5 films. The parasitic switching behavior can be observed in the specific operation condition. Dual bipolar resistance switching behaviors of filament-type and interface-type can coexist in the devices by appropriate voltage operation. In addition, the relationship between filament-type and interface-type switching behaviors were studied
In addition, HfO2 which is a popular resistive switching material is investigated for multi-level non-volatile memory applications. We develop a gradual soft breakdown technology combine with the different temperature measurement system to extract the temperature coefficient of the different resistance state. The results indicate as the compliance current increases, the transportation mechanism switches from hopping (semiconductor-like) to ohmic conduction (metal-like). Due to hopping barrier decreases, the ρ become lower before the critical compliance current of 300uA. When the compliance current becomes larger than 300uA, the electrons go through a metal-like conducting path. As the compliance current become larger, the corresponding filament area A become larger to make more electron can transport though the metal filament. The formation of filament of HfO2 RRAM should be divided into two steps, the purification and the reproduction.
Besides, nonvolatile memory characteristics of Ti/Al2O¬3/Pt embedded with Ni nanocrystals is investigated in order to improve the behavior of RRAM. The cross-section TEM and XPS results shows that the formation of Ni nanocrystals after the 500℃ annealing. The device characteristics of RRAM can be stabilized by embedding nanocrystals. It is due to the conductive path can be confined through the nanocrystals instead of forming randomly in the device which is without nanocrystals. Therefore, the structure with embedded nanocrystals can be applied in next generation nonvolatile memory application.
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Liu, Chun-Chih, and 劉峻志. "Characterization of Resistive Random Access Memory Devices Based on Al2O3/TiO2." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/01300858097947120937.
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碩士<br>國立交通大學<br>電子研究所<br>100<br>With the technology development, the nonvolatile memory (NVM) plays an important role in our daily life. The flash memory is considered as the mainstream. However, due to the further scaling limitation, it faces serious challenges, such as high operation voltage, low program/erase (P/E) speed, etc.
The resistive random access memory (RRAM) shows a great potential for the next generation NVM application, due to its low operation voltage, high P/E speed, low power and simple structure, etc.
In this thesis, we propose a RRAM device using Al2O3/TiO2 as the resistive materials, and also investigate the effect of different top electrode (Nickel, Titanium). The RRAM device characteristics, such as I-V curve, data retention, endurance and conduction mechanism, etc., are investigated. The work function of the Nickel (Ni) is about 5.2 eV, while the work function of the Titanium (Ti) is about 4.3 eV. The top electrode with different work function may have influences for the electrical properties. This Al2O3/TiO2 RRAM device exhibits good memory characteristics, showing a great promise in future scalable memory application.
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Wu, Hsin-Han, and 吳欣翰. "Assembly of Reliability Measurement System for Resistive Random Access Memory Devices." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/15917059911075640634.
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碩士<br>國立交通大學<br>材料科學與工程學系所<br>101<br>Resistive random access memory (RRAM) has been recognized as the next-generation nonvolatile memory and its reliability is one of the key issues to access the device performance. In this study, personal computer, Keithley 2400 I-V sourcemeter and Agilent 81110a pulse generator are adopted as the main hardware of the reliability measurement system whereas the data acquisition is accomplished via the LabVIEW programming language. The system operates based on the timeline concept instead of using the switching box commonly seen in other multi-instruments measurements.
The system established in this study can be divided into three subsystems including: (1) automatically double-sweeping I-V curve measurement system which commands Keithley 2400 sourcemeter into four individual voltage sweep steps. It may automatically read out the electrical properties including RHRS, RLRS, VSET and VRESET when LabVIEW collects the raw I-V-R data; (2) semi-automatic endurance measurement system which may precisely control the output signals from the pulse generator based on the timeline concept and subsequently provide the resistivity-cycle profiles and the I-V curves; (3) automatic long-time retention measurement system which sets the starting point of timeline by Agilent 81110a and controls the interval time between two resistivity-read command of Keithley 2400 so as to record the long-time retention property of RRAM devices.
The advantages of the whole system include cross-brand instrument integration, high degree of freedom of measurement, convenience of data analysis and low assembly cost. However, the endurance system can only be semi-automatic since the abandon of switch box inevitably requires the manual circuit exchange during I-V measurement.
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Pan, Hsin Wei, and 潘信瑋. "A Novel Resistive Random Access Memory in FinFET CMOS Logic Technology." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/58689841857559825349.
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碩士<br>國立清華大學<br>電子工程研究所<br>103<br>Recently ,due to the rapidly developing of commercial electronics, the demands of fast and mass storage devices increase. Flash memory dominates the market of nonvolatile memory. However with the technology scaling down, flash memory come up with many challenge, such as inadequate charge storage, high operation voltage and physical limit, which urges the study of novel nonvolatile memory. In which, RRAM is the most promising candidate for the next generation.
In this studies, we propose a novel FINFET Dielectric (FIND) RRAM, which is fully compatible with FinFET CMOS logic process without extra mask or additional process flow. The cell size of the FIND RRAM is only 0.07632μm2, which is highly competitive. The electrical analysis shows low operation voltage and short switching time. Moreover, excellent set/reset disturb immunity and data retention at 150oC for 1000 hours further prove its superior reliability.
In this dissertation, a highly dense 1kb NOR-type FIND RRAM array is successfully demonstrated.. Without the requirement of extra masks, this cell featuring fast operation speed, extremely small and outstanding reliability and scalability is one of the promising solutions for nonvolatile memory in the near future.
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Lin, Chih-Yang, and 林志洋. "Fabrication, Modification, and Characterization of Resistive Random Access Memory (RRAM) Devices." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/23014069235195776472.
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博士<br>國立交通大學<br>電子工程系所<br>96<br>With the arrival of Digital Age, nonvolatile memory (NVM) plays an important role for portable electronic products, such as the mobile phone, digital camera, and notebook computer. Flash memory is the mainstream among the nonvolatile memory devices nowadays, but it has many drawbacks, including high operation voltage, low operation speed, and poor endurance. In addition, when the device dimensions are continuously scaled down, the flash memory faces the challenge of thin tunneling oxide that causes an unsatisfactory retention time. Consequently, there are many proposals for new nonvolatile memories such as the ferroelectric random access memory (FeRAM), the magnetic random access memory (MRAM), and the resistive random access memory (RRAM). As for RRAM, the digital data can be stored in two memory states with high and low resistivities, ON-state and OFF-state, respectively. The two memory states can be easily switched by voltage biases or pulses, which enhance the possibility of the application in circuit level.
In the International Electron Devices Meeting (IEDM) in 2002, Sharp company reported that RRAM had advantages over both dynamic random access memory (DRAM) and flash memory due to its nonvolatility, simple device structure, and high operation speed. Thereafter, much attention devoted to the development of RRAM devices. Resistive switching phenomena have been observed in many materials, which can be roughly categorized into four groups (1) organic molecular materials, (2) solid state electrolytes (or called programmable metallization cell), (3) perovskite structures such as SrZrO3 (SZO), SrTiOx and Pr0.7Ca0.3MnO3, and (4) transition metal oxides (TMOs) such as NiO, TiO2, ZrO2, Cu2O, and etc.
There are still many important unresolved problems, including the original resistive switching mechanisms and the reliability issues (such as endurance test, reset failure, and variations of resistive switching parameters), which are all needed to be identified before realizing commercial applications. The major goals of the dissertation are to give more insights into these issues and find solutions to them.
The purpose of this research focuses on the fundamentals of the SZO- and ZrO2-based resistive switching memory devices. Based on the basic understandings, the SZO- and ZrO2-based memory device is modified to achieve the improvements in the device yield, reliability, and manufacturability for the next-generation nonvolatile memory application. We have proposed novel, simple, and effective manners by embedding a thin Cr layer and using Ti top electrode, which causes an inner space charge region and a self-aligned interface. No extra manufacture cost is needed to improve the device performance. Moreover, the self-aligned interface serves as a series resistance and an oxygen sink, which is demonstrated to be important for the enhancement of the device characteristics. In the final part of this dissertation, the conclusions and the suggested future works are presented.
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Chen, Ying-Chan, and 陳昱丞. "Bipolar Switching properties of HfO2 based Resistive Random Access Memory Devices." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/50170076258052413995.
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Wan-YingLi and 李宛頴. "The characteristics of AlN films for random resistive access memory application." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/30174454432663195206.
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碩士<br>國立成功大學<br>奈米科技暨微系統工程研究所<br>100<br>AlN thin films were deposited on Pt/Ti/SiO2/Si using radio-frequency magnetron sputtering technique and were followed by four different top electrodes (aluminum, silver, titanium, platinum) to evaluate the dependence of the resistive switching characteristics. Besides, the deposition time and the nitrogen content in the sputtering atmosphere were changed to obtain different thickness and constituent of AlN thin films separately. Through different experimental parameters, the influence of film thickness and defects on the resistive switching behavior were discussed. At last, the influence of post-annealing conditions on the electrical properties of AlN thin films were also investigated. Through analyzing the electrical resistive switching characteristics, set and reset voltage and on/off ratio, we tried to clarify the mechanism of resistance switching more clearly.
Several important results were found from above studies. First, the resistive switching came from electrons which hopped between the nitride related defects. Second, under high resistive state, the trap-controlled space charge limited current can be seen. Third, the composition of AlN film and post-annealing would change the number of nitride related vacancies. They made effects on forming voltage and the resistance ratios of the HRS and to LRS.
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Chang, You-Tai, and 張佑臺. "Schottky Diode Based Selector for High-Density Resistive Random Access Memory." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/54078011685915264326.
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碩士<br>國立清華大學<br>工程與系統科學系<br>101<br>Resistive random access memory(RRAM) is the hottest topic of nonvolatile memory studies. The advantages of RRAM are simple structure, fast switching speed, low voltage operation, easy for CMOS integration.
There are many applications of RRAM like cross-bar array for high density of cells or integrated with logic cells with the structure of 1 transistor + 1 RRAM(1T1R). The cross-bar array is the excellent idea to accomplish high density of memory cells array. But sneak current from cross-bar array must be avoided. There are some ways to avoid sneak current are known as 1 Selection device + 1 RRAM(1S1R), 1 diode + 1 RRAM(1D1R) or complementary resistive switching memory. The schottky diode of 1D1R cross-bar array are chosen with high integrating power with RRAM and simple structure. Finally, the ZrTiOx(ZTO) were used to be dielectric and the structure of TaN/ZTO/Ni/N-Si could have 10% of read windows with 100 word line or bit line number. For simple structure TaN/ZTO/Ni/N-Si is potential for RRAM array.
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Lai, Li-Ya, and 賴俐雅. "A High Efficiency Automatic Write Mechanism for Resistive Random Access Memory." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/y53rsr.
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