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Sample records for volatile memory device

  1. Flexible non-volatile memory devices based on organic semiconductors

    Science.gov (United States)

    Cosseddu, Piero; Casula, Giulia; Lai, Stefano; Bonfiglio, Annalisa

    2015-09-01

    The possibility of developing fully organic electronic circuits is critically dependent on the ability to realize a full set of electronic functionalities based on organic devices. In order to complete the scene, a fundamental element is still missing, i.e. reliable data storage. Over the past few years, a considerable effort has been spent on the development and optimization of organic polymer based memory elements. Among several possible solutions, transistor-based memories and resistive switching-based memories are attracting a great interest in the scientific community. In this paper, a route for the fabrication of organic semiconductor-based memory devices with performances beyond the state of the art is reported. Both the families of organic memories will be considered. A flexible resistive memory based on a novel combination of materials is presented. In particular, high retention time in ambient conditions are reported. Complementary, a low voltage transistor-based memory is presented. Low voltage operation is allowed by an hybrid, nano-sized dielectric, which is also responsible for the memory effect in the device. Thanks to the possibility of reproducibly fabricating such device on ultra-thin substrates, high mechanical stability is reported.

  2. Metal-organic molecular device for non-volatile memory storage

    Energy Technology Data Exchange (ETDEWEB)

    Radha, B., E-mail: radha.boya@manchester.ac.uk, E-mail: kulkarni@jncasr.ac.in; Sagade, Abhay A.; Kulkarni, G. U., E-mail: radha.boya@manchester.ac.uk, E-mail: kulkarni@jncasr.ac.in [Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India)

    2014-08-25

    Non-volatile memory devices have been of immense research interest for their use in active memory storage in powered off-state of electronic chips. In literature, various molecules and metal compounds have been investigated in this regard. Molecular memory devices are particularly attractive as they offer the ease of storing multiple memory states in a unique way and also represent ubiquitous choice for miniaturized devices. However, molecules are fragile and thus the device breakdown at nominal voltages during repeated cycles hinders their practical applicability. Here, in this report, a synergetic combination of an organic molecule and an inorganic metal, i.e., a metal-organic complex, namely, palladium hexadecylthiolate is investigated for memory device characteristics. Palladium hexadecylthiolate following partial thermolysis is converted to a molecular nanocomposite of Pd(II), Pd(0), and long chain hydrocarbons, which is shown to exhibit non-volatile memory characteristics with exceptional stability and retention. The devices are all solution-processed and the memory action stems from filament formation across the pre-formed cracks in the nanocomposite film.

  3. Non-volatile memory devices with redox-active diruthenium molecular compound

    Science.gov (United States)

    Pookpanratana, S.; Zhu, H.; Bittle, E. G.; Natoli, S. N.; Ren, T.; Richter, C. A.; Li, Q.; Hacker, C. A.

    2016-03-01

    Reduction-oxidation (redox) active molecules hold potential for memory devices due to their many unique properties. We report the use of a novel diruthenium-based redox molecule incorporated into a non-volatile Flash-based memory device architecture. The memory capacitor device structure consists of a Pd/Al2O3/molecule/SiO2/Si structure. The bulky ruthenium redox molecule is attached to the surface by using a ‘click’ reaction and the monolayer structure is characterized by x-ray photoelectron spectroscopy to verify the Ru attachment and molecular density. The ‘click’ reaction is particularly advantageous for memory applications because of (1) ease of chemical design and synthesis, and (2) provides an additional spatial barrier between the oxide/silicon to the diruthenium molecule. Ultraviolet photoelectron spectroscopy data identified the energy of the electronic levels of the surface before and after surface modification. The molecular memory devices display an unsaturated charge storage window attributed to the intrinsic properties of the redox-active molecule. Our findings demonstrate the strengths and challenges with integrating molecular layers within solid-state devices, which will influence the future design of molecular memory devices.

  4. Fabrication of spray-printed organic non-volatile memory devices for low cost electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Cha, An-Na [Soft Innovative Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101 Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do (Korea, Republic of); Professional Graduate School of Flexible and Printable Electronics and Polymer Materials Fusion Research Center, Chonbuk National University, 664-14, Deokjin-dong, Deokjin-gu, Jeonju-si, Jeollabuk-do 561-756 (Korea, Republic of); Ji, Yongsung [Soft Innovative Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101 Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do (Korea, Republic of); Lee, Sang-A [Soft Innovative Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101 Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do (Korea, Republic of); Department of Polymer-Nano Science and Technology, Chonbuk National University, 664-14 Duckjin-dong, Duckjin-gu, Jeonju 561-756 (Korea, Republic of); Noh, Yong-Young [Department of Energy and Materials Engineering, Dongguk University, 26 Pil-dong, 3-Ga, Jung-gu, Seoul 100-715 (Korea, Republic of); Na, Seok-In [Professional Graduate School of Flexible and Printable Electronics and Polymer Materials Fusion Research Center, Chonbuk National University, 664-14, Deokjin-dong, Deokjin-gu, Jeonju-si, Jeollabuk-do 561-756 (Korea, Republic of); Bae, Sukang; Lee, Sanghyun [Soft Innovative Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101 Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do (Korea, Republic of); Kim, Tae-Wook, E-mail: twkim@kist.re.kr [Soft Innovative Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology, San 101 Eunha-ri, Bongdong-eup, Wanju-gun, Jeollabuk-do (Korea, Republic of)

    2015-01-15

    Highlights: • PS:PCBM-based organic non-volatile memory devices was fabricated using spray printing. • The thickness of the film was controlled by adjusting the concentration of the PS:PCBM solutions. • The roughness of spray-printed films was poorer than that of the spin-coated film. • The minimum thickness of the printed film influenced the memory behavior more than the surface roughness. • The spray printed PS:PCBM showed excellent unipolar switching, reliability, retention, and endurance characteristics. - Abstract: We fabricated polystyrene (PS) and 6-phenyl-C61 butyric acid methyl ester (PCBM) based organic non-volatile memory devices using a spray printing technique. Due to the distinct operational properties of this technique, significant differences were observed in the macro- and microscopic features (e.g., the film quality and surface roughness) of the devices. The thickness of the film was successfully controlled by adjusting the concentration of the PS:PCBM solutions sprayed. Although the roughness of the spray-printed films was poorer than that of the spin-coated film, negligible differences were observed in the basic memory characteristics (e.g., the operation voltage range, turn on and off voltage, retention and endurance). In particular, the printing-based organic memory devices were successfully switched, as exhibited by the on/off ratio greater than two orders of magnitude at 0.3 V read voltage. The resistance state of all of the devices was maintained for more than 10{sup 4} s, indicating their non-volatile characteristics.

  5. A robust molecular platform for non-volatile memory devices with optical and magnetic responses.

    Science.gov (United States)

    Simão, Cláudia; Mas-Torrent, Marta; Crivillers, Núria; Lloveras, Vega; Artés, Juan Manuel; Gorostiza, Pau; Veciana, Jaume; Rovira, Concepció

    2011-05-01

    Bistable molecules that behave as switches in solution have long been known. Systems that can be reversibly converted between two stable states that differ in their physical properties are particularly attractive in the development of memory devices when immobilized in substrates. Here, we report a highly robust surface-confined switch based on an electroactive, persistent organic radical immobilized on indium tin oxide substrates that can be electrochemically and reversibly converted to the anion form. This molecular bistable system behaves as an extremely robust redox switch in which an electrical input is transduced into optical as well as magnetic outputs under ambient conditions. The fact that this molecular surface switch, operating at very low voltages, can be patterned and addressed locally, and also has exceptionally high long-term stability and excellent reversibility and reproducibility, makes it a very promising platform for non-volatile memory devices.

  6. MIEC (mixed-ionic-electronic-conduction)-based access devices for non-volatile crossbar memory arrays

    Science.gov (United States)

    Shenoy, Rohit S.; Burr, Geoffrey W.; Virwani, Kumar; Jackson, Bryan; Padilla, Alvaro; Narayanan, Pritish; Rettner, Charles T.; Shelby, Robert M.; Bethune, Donald S.; Raman, Karthik V.; BrightSky, Matthew; Joseph, Eric; Rice, Philip M.; Topuria, Teya; Kellock, Andrew J.; Kurdi, Bülent; Gopalakrishnan, Kailash

    2014-10-01

    Several attractive applications call for the organization of memristive devices (or other resistive non-volatile memory (NVM)) into large, densely-packed crossbar arrays. While resistive-NVM devices frequently possess some degree of inherent nonlinearity (typically 3-30× contrast), the operation of large (\\gt 1000×1000 device) arrays at low power tends to require quite large (\\gt 1e7) ON-to-OFF ratios (between the currents passed at high and at low voltages). One path to such large nonlinearities is the inclusion of a distinct access device (AD) together with each of the state-bearing resistive-NVM elements. While such an AD need not store data, its list of requirements is almost as challenging as the specifications demanded of the memory device. Several candidate ADs have been proposed, but obtaining high performance without requiring single-crystal silicon and/or the high processing temperatures of the front-end-of-the-line—which would eliminate any opportunity for 3D stacking—has been difficult. We review our work at IBM Research—Almaden on high-performance ADs based on Cu-containing mixed-ionic-electronic conduction (MIEC) materials [1-7]. These devices require only the low processing temperatures of the back-end-of-the-line, making them highly suitable for implementing multi-layer cross-bar arrays. MIEC-based ADs offer large ON/OFF ratios (\\gt 1e7), a significant voltage margin {{V}m} (over which current \\lt 10 nA), and ultra-low leakage (\\lt 10 pA), while also offering the high current densities needed for phase-change memory and the fully bipolar operation needed for high-performance RRAM. Scalability to critical lateral dimensions \\lt 30 nm and thicknesses \\lt 15 nm, tight distributions and 100% yield in large (512 kBit) arrays, long-term stability of the ultra-low leakage states, and sub-50 ns turn-ON times have all been demonstrated. Numerical modeling of these MIEC-based ADs shows that their operation depends on C{{u}+} mediated hole

  7. Non-volatile memories

    CERN Document Server

    Lacaze, Pierre-Camille

    2014-01-01

    Written for scientists, researchers, and engineers, Non-volatile Memories describes the recent research and implementations in relation to the design of a new generation of non-volatile electronic memories. The objective is to replace existing memories (DRAM, SRAM, EEPROM, Flash, etc.) with a universal memory model likely to reach better performances than the current types of memory: extremely high commutation speeds, high implantation densities and retention time of information of about ten years.

  8. Low-temperature process steps for realization of non-volatile memory devices

    NARCIS (Netherlands)

    Brunets, I.; Boogaard, A.; Aarnink, A.A.I.; Kovalgin, A.Y.; Wolters, R.A.M.; Holleman, J.; Schmitz, J.

    2007-01-01

    In this work, the low-temperature process steps required for the realization of nano-crystal non-volatile memory cells are discussed. An amorphous silicon film, crystallized using a diode pumped solid state green laser irradiating at 532 nm, is proposed as an active layer. The deposition of the subs

  9. Electric field mediated non-volatile tuning magnetism in CoPt/PMN-PT heterostructure for magnetoelectric memory devices

    Science.gov (United States)

    Yang, Y. T.; Li, J.; Peng, X. L.; Wang, X. Q.; Wang, D. H.; Cao, Q. Q.; Du, Y. W.

    2016-02-01

    We report a power efficient non-volatile magnetoelectric memory in the CoPt/(011)PMN-PT heterostructure. Two reversible and stable electric field induced coercivity states (i.e., high-HC or low-HC) are obtained due to the strain mediated converse magnetoelectric effect. The reading process of the different coercive field information written by electric fields is demonstrated by using a magnetoresistance read head. This result shows good prospects in the application of novel multiferroic devices.

  10. Towards the development of flexible non-volatile memories.

    Science.gov (United States)

    Han, Su-Ting; Zhou, Ye; Roy, V A L

    2013-10-11

    Flexible non-volatile memories have attracted tremendous attentions for data storage for future electronics application. From device perspective, the advantages of flexible memory devices include thin, lightweight, printable, foldable and stretchable. The flash memories, resistive random access memories (RRAM) and ferroelectric random access memory/ferroelectric field-effect transistor memories (FeRAM/FeFET) are considered as promising candidates for next generation non-volatile memory device. Here, we review the general background knowledge on device structure, working principle, materials, challenges and recent progress with the emphasis on the flexibility of above three categories of non-volatile memories.

  11. Emerging non-volatile memories

    CERN Document Server

    Hong, Seungbum; Wouters, Dirk

    2014-01-01

    This book is an introduction to the fundamentals of emerging non-volatile memories and provides an overview of future trends in the field. Readers will find coverage of seven important memory technologies, including Ferroelectric Random Access Memory (FeRAM), Ferromagnetic RAM (FMRAM), Multiferroic RAM (MFRAM), Phase-Change Memories (PCM), Oxide-based Resistive RAM (RRAM), Probe Storage, and Polymer Memories. Chapters are structured to reflect diffusions and clashes between different topics. Emerging Non-Volatile Memories is an ideal book for graduate students, faculty, and professionals working in the area of non-volatile memory. This book also: Covers key memory technologies, including Ferroelectric Random Access Memory (FeRAM), Ferromagnetic RAM (FMRAM), and Multiferroic RAM (MFRAM), among others. Provides an overview of non-volatile memory fundamentals. Broadens readers' understanding of future trends in non-volatile memories.

  12. Low-temperature LPCVD of Si nanocrystals from disilane and trisilane (Silcore®) embedded in ALD-alumina for non-volatile memory devices

    NARCIS (Netherlands)

    Brunets, I.; Aarnink, A.A.I.; Boogaard, A.; Kovalgin, A.Y.; Wolters, R.A.M.; Holleman, J.; Schmitz, J.

    2007-01-01

    Non-volatile memory devices are realized using CVD and ALD of all active layers in a cluster tool. The floating gate consists of silicon nanocrystals. A high nanocrystal density was obtained through an enhanced nucleation rate by using disilane (Si2H6) as well as trisilane (Si3H8, known as Silcore®)

  13. Combination of volatile and non-volatile functions in a single memory cell and its scalability

    Science.gov (United States)

    Kim, Hyungjin; Hwang, Sungmin; Lee, Jong-Ho; Park, Byung-Gook

    2017-04-01

    A single memory cell which combines volatile memory and non-volatile memory functions has been demonstrated with an independent asymmetric dual-gate structure. Owing to the second gate whose dielectric is composed of oxide/nitride/oxide layers, floating body effect was observed even on a fully depleted silicon-on-insulator device and the non-volatile memory function was measured. In addition, read retention characteristics of the volatile memory function depending on the non-volatile memory state were evaluated and analyzed. Further scalability in body thickness was also verified through simulation studies. These results indicate that the proposed device is a promising candidate for high-density embedded memory applications.

  14. Flexible non-volatile optical memory thin-film transistor device with over 256 distinct levels based on an organic bicomponent blend

    Science.gov (United States)

    Leydecker, Tim; Herder, Martin; Pavlica, Egon; Bratina, Gvido; Hecht, Stefan; Orgiu, Emanuele; Samorì, Paolo

    2016-09-01

    Organic nanomaterials are attracting a great deal of interest for use in flexible electronic applications such as logic circuits, displays and solar cells. These technologies have already demonstrated good performances, but flexible organic memories are yet to deliver on all their promise in terms of volatility, operational voltage, write/erase speed, as well as the number of distinct attainable levels. Here, we report a multilevel non-volatile flexible optical memory thin-film transistor based on a blend of a reference polymer semiconductor, namely poly(3-hexylthiophene), and a photochromic diarylethene, switched with ultraviolet and green light irradiation. A three-terminal device featuring over 256 (8 bit storage) distinct current levels was fabricated, the memory states of which could be switched with 3 ns laser pulses. We also report robustness over 70 write-erase cycles and non-volatility exceeding 500 days. The device was implemented on a flexible polyethylene terephthalate substrate, validating the concept for integration into wearable electronics and smart nanodevices.

  15. GaAs metal-oxide-semiconductor based non-volatile flash memory devices with InAs quantum dots as charge storage nodes

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Sk Masiul, E-mail: masiulelt@gmail.com; Chowdhury, Sisir; Sarkar, Krishnendu; Nagabhushan, B.; Banerji, P. [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Chakraborty, S. [Applied Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Sector-I, Kolkata 700 064 (India); Mukherjee, Rabibrata [Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302 (India)

    2015-06-24

    Ultra-thin InP passivated GaAs metal-oxide-semiconductor based non-volatile flash memory devices were fabricated using InAs quantum dots (QDs) as charge storing elements by metal organic chemical vapor deposition technique to study the efficacy of the QDs as charge storage elements. The grown QDs were embedded between two high-k dielectric such as HfO{sub 2} and ZrO{sub 2}, which were used for tunneling and control oxide layers, respectively. The size and density of the QDs were found to be 5 nm and 1.8×10{sup 11} cm{sup −2}, respectively. The device with a structure Metal/ZrO{sub 2}/InAs QDs/HfO{sub 2}/GaAs/Metal shows maximum memory window equivalent to 6.87 V. The device also exhibits low leakage current density of the order of 10{sup −6} A/cm{sup 2} and reasonably good charge retention characteristics. The low value of leakage current in the fabricated memory device is attributed to the Coulomb blockade effect influenced by quantum confinement as well as reduction of interface trap states by ultra-thin InP passivation on GaAs prior to HfO{sub 2} deposition.

  16. An overview of Experimental Condensed Matter Physics in Argentina by 2014, and Oxides for Non Volatile Memory Devices: The MeMOSat Project

    Science.gov (United States)

    Levy, Pablo

    2015-03-01

    In the first part of my talk, I will describe the status of the experimental research in Condensed Matter Physics in Argentina, biased towards developments related to micro and nanotechnology. In the second part, I will describe the MeMOSat Project, a consortium aimed at producing non-volatile memory devices to work in aggressive environments, like those found in the aerospace and nuclear industries. Our devices rely on the Resistive Switching mechanism, which produces a permanent but reversible change in the electrical resistance across a metal-insulator-metal structure by means of a pulsed protocol of electrical stimuli. Our project is devoted to the study of Memory Mechanisms in Oxides (MeMO) in order to establish a technological platform that tests the Resistive RAM (ReRAM) technology for aerospace applications. A review of MeMOSat's activities is presented, covering the initial Proof of Concept in ceramic millimeter sized samples; the study of different oxide-metal couples including (LaPr)2/3Ca1/3MnO, La2/3Ca1/3MnO3, YBa2Cu3O7, TiO2, HfO2, MgO and CuO; and recent miniaturized arrays of micrometer sized devices controlled by in-house designed electronics, which were launched with the BugSat01 satellite in June2014 by the argentinian company Satellogic.

  17. Laser Nanosoldering of Golden and Magnetite Particles and its Possible Application in 3D Printing Devices and Four-Valued Non-Volatile Memories

    Directory of Open Access Journals (Sweden)

    Jaworski Jacek

    2015-12-01

    Full Text Available In recent years the 3D printing methods have been developing rapidly. This article presents researches about a new composite consisted of golden and magnetite nanoparticles which could be used for this technique. Preparation of golden nanoparticles by laser ablation and their soldering by laser green light irradiation proceeded in water environment. Magnetite was obtained on chemical way. During experiments it was tested a change of a size of nanoparticles during laser irradiation, surface plasmon resonance, zeta potential. The obtained golden - magnetite composite material was magnetic after laser irradiation. On the end there was considered the application it for 3D printing devices, water filters and four-valued non-volatile memories.

  18. Securing non-volatile memory regions

    Science.gov (United States)

    Faraboschi, Paolo; Ranganathan, Parthasarathy; Muralimanohar, Naveen

    2013-08-20

    Methods, apparatus and articles of manufacture to secure non-volatile memory regions are disclosed. An example method disclosed herein comprises associating a first key pair and a second key pair different than the first key pair with a process, using the first key pair to secure a first region of a non-volatile memory for the process, and using the second key pair to secure a second region of the non-volatile memory for the same process, the second region being different than the first region.

  19. EDITORIAL: Non-volatile memory based on nanostructures Non-volatile memory based on nanostructures

    Science.gov (United States)

    Kalinin, Sergei; Yang, J. Joshua; Demming, Anna

    2011-06-01

    Non-volatile memory refers to the crucial ability of computers to store information once the power source has been removed. Traditionally this has been achieved through flash, magnetic computer storage and optical discs, and in the case of very early computers paper tape and punched cards. While computers have advanced considerably from paper and punched card memory devices, there are still limits to current non-volatile memory devices that restrict them to use as secondary storage from which data must be loaded and carefully saved when power is shut off. Denser, faster, low-energy non-volatile memory is highly desired and nanostructures are the critical enabler. This special issue on non-volatile memory based on nanostructures describes some of the new physics and technology that may revolutionise future computers. Phase change random access memory, which exploits the reversible phase change between crystalline and amorphous states, also holds potential for future memory devices. The chalcogenide Ge2Sb2Te5 (GST) is a promising material in this field because it combines a high activation energy for crystallization and a relatively low crystallization temperature, as well as a low melting temperature and low conductivity, which accommodates localized heating. Doping is often used to lower the current required to activate the phase change or 'reset' GST but this often aggravates other problems. Now researchers in Korea report in-depth studies of SiO2-doped GST and identify ways of optimising the material's properties for phase-change random access memory [1]. Resistance switching is an area that has attracted a particularly high level of interest for non-volatile memory technology, and a great deal of research has focused on the potential of TiO2 as a model system in this respect. Researchers at HP labs in the US have made notable progress in this field, and among the work reported in this special issue they describe means to control the switch resistance and show

  20. Memory and Spin Injection Devices Involving Half Metals

    Directory of Open Access Journals (Sweden)

    M. Shaughnessy

    2011-01-01

    Full Text Available We suggest memory and spin injection devices fabricated with half-metallic materials and based on the anomalous Hall effect. Schematic diagrams of the memory chips, in thin film and bulk crystal form, are presented. Spin injection devices made in thin film form are also suggested. These devices do not need any external magnetic field but make use of their own magnetization. Only a gate voltage is needed. The carriers are 100% spin polarized. Memory devices may potentially be smaller, faster, and less volatile than existing ones, and the injection devices may be much smaller and more efficient than existing spin injection devices.

  1. Channel equalization techniques for non-volatile memristor memories

    KAUST Repository

    Naous, Rawan

    2016-03-16

    Channel coding and information theoretic approaches have been utilized in conventional non-volatile memories to overcome their inherent design limitations of leakage, coupling and refresh rates. However, the continuous scaling and integration constraints set on the current devices directed the attention towards emerging memory technologies as suitable alternatives. Memristive devices are prominent candidates to replace the conventional electronics due to its non-volatility and small feature size. Nonetheless, memristor-based memories still encounter an accuracy limitation throughout the read operation addressed as the sneak path phenomenon. The readout data is corrupted with added distortion that increases significantly the bit error rate and jeopardizes the reliability of the read operation. A novel technique is applied to alleviate this distorting effect where the communication channel model is proposed for the memory array. Noise cancellation principles are applied with the aid of preset pilots to extract channel information and adjust the readout values accordingly. The proposed technique has the virtue of high speed, energy efficiency, and low complexity design while achieving high reliability and error-free decoding.

  2. Long memory and tail dependence in trading volume and volatility

    DEFF Research Database (Denmark)

    Rossi, Eduardo; Santucci de Magistris, Paolo

    2013-01-01

    We investigate the relationship between volatility, measured by realized volatility, and trading volume for 25 NYSE stocks. We show that volume and volatility are long memory but not fractionally cointegrated in most cases. We also find right tail dependence in the volatility and volume innovations...

  3. Long memory and tail dependence in trading volume and volatility

    DEFF Research Database (Denmark)

    Rossi, Eduardo; Santucci de Magistris, Paolo

    2013-01-01

    We investigate the relationship between volatility, measured by realized volatility, and trading volume for 25 NYSE stocks. We show that volume and volatility are long memory but not fractionally cointegrated in most cases. We also find right tail dependence in the volatility and volume innovations...

  4. Analyzing Malware Based on Volatile Memory

    Directory of Open Access Journals (Sweden)

    Liang Hu

    2013-11-01

    Full Text Available To explain the necessity of comprehensive and automatically analysis process for volatile memory, this paper summarized ordinarily analyzing methods and their common points especially for concerned data source. Then, a memory analysis framework Volatiltiy-2.2 and statistical output file size are recommended. In addition, to address the limitation of plug-ins classification in analyzing procedure, a user perspective classify is necessary and proposed. Furthermore, according to target data source differences on the base of result data set volume and employed relational method is introduced for comprehensive analysis guideline procedure. Finally, a test demo including DLLs loading order list analyzing is recommend, in which DLL load list is regard as different kind of characteristics typical data source with process and convert into process behavior fingerprint. The clustering for the fingerprint is employed string similar degree algorithm model in the demo, which has a wide range applications in traditional malware behavior analysis, and it is proposed that these methods also can be applied for volatile memory

  5. Novel Molecular Non-Volatile Memory: Application of Redox-Active Molecules

    Directory of Open Access Journals (Sweden)

    Hao Zhu

    2015-12-01

    Full Text Available This review briefly describes the development of molecular electronics in the application of non-volatile memory. Molecules, especially redox-active molecules, have become interesting due to their intrinsic redox behavior, which provides an excellent basis for low-power, high-density and high-reliability non-volatile memory applications. Recently, solid-state non-volatile memory devices based on redox-active molecules have been reported, exhibiting fast speed, low operation voltage, excellent endurance and multi-bit storage, outperforming the conventional floating-gate flash memory. Such high performance molecular memory will lead to promising on-chip memory and future portable/wearable electronics applications.

  6. Filamentary Switching: Synaptic Plasticity through Device Volatility

    CERN Document Server

    La Barbera, Selina; Alibart, Fabien

    2015-01-01

    Replicating the computational functionalities and performances of the brain remains one of the biggest challenges for the future of information and communication technologies. Such an ambitious goal requires research efforts from the architecture level to the basic device level (i.e., investigating the opportunities offered by emerging nanotechnologies to build such systems). Nanodevices, or, more precisely, memory or memristive devices, have been proposed for the implementation of synaptic functions, offering the required features and integration in a single component. In this paper, we demonstrate that the basic physics involved in the filamentary switching of electrochemical metallization cells can reproduce important biological synaptic functions that are key mechanisms for information processing and storage. The transition from short- to long-term plasticity has been reported as a direct consequence of filament growth (i.e., increased conductance) in filamentary memory devices. In this paper, we show tha...

  7. Overview of one transistor type of hybrid organic ferroelectric non-volatile memory

    Institute of Scientific and Technical Information of China (English)

    Young; Tea; Chun; Daping; Chu

    2015-01-01

    Organic ferroelectric memory devices based on field effect transistors that can be configured between two stable states of on and off have been widely researched as the next generation data storage media in recent years.This emerging type of memory devices can lead to a new instrument system as a potential alternative to previous non-volatile memory building blocks in future processing units because of their numerous merits such as cost-effective process,simple structure and freedom in substrate choices.This bi-stable non-volatile memory device of information storage has been investigated using several organic or inorganic semiconductors with organic ferroelectric polymer materials.Recent progresses in this ferroelectric memory field,hybrid system have attracted a lot of attention due to their excellent device performance in comparison with that of all organic systems.In this paper,a general review of this type of ferroelectric non-volatile memory is provided,which include the device structure,organic ferroelectric materials,electrical characteristics and working principles.We also present some snapshots of our previous study on hybrid ferroelectric memories including our recent work based on zinc oxide nanowire channels.

  8. Method for refreshing a non-volatile memory

    Science.gov (United States)

    Riekels, James E.; Schlesinger, Samuel

    2008-11-04

    A non-volatile memory and a method of refreshing a memory are described. The method includes allowing an external system to control refreshing operations within the memory. The memory may generate a refresh request signal and transmit the refresh request signal to the external system. When the external system finds an available time to process the refresh request, the external system acknowledges the refresh request and transmits a refresh acknowledge signal to the memory. The memory may also comprise a page register for reading and rewriting a data state back to the memory. The page register may comprise latches in lieu of supplemental non-volatile storage elements, thereby conserving real estate within the memory.

  9. Rad hard Non volatile memory for FPGA boot loading Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Radiation-hardened non volatile memory is needed to store the golden copy of the image(s) has not kept pace with the advances in FPGAs. Consider that a single image...

  10. Scalable printed electronics: an organic decoder addressing ferroelectric non-volatile memory

    Science.gov (United States)

    Ng, Tse Nga; Schwartz, David E.; Lavery, Leah L.; Whiting, Gregory L.; Russo, Beverly; Krusor, Brent; Veres, Janos; Bröms, Per; Herlogsson, Lars; Alam, Naveed; Hagel, Olle; Nilsson, Jakob; Karlsson, Christer

    2012-08-01

    Scalable circuits of organic logic and memory are realized using all-additive printing processes. A 3-bit organic complementary decoder is fabricated and used to read and write non-volatile, rewritable ferroelectric memory. The decoder-memory array is patterned by inkjet and gravure printing on flexible plastics. Simulation models for the organic transistors are developed, enabling circuit designs tolerant of the variations in printed devices. We explain the key design rules in fabrication of complex printed circuits and elucidate the performance requirements of materials and devices for reliable organic digital logic.

  11. Scalable printed electronics: an organic decoder addressing ferroelectric non-volatile memory

    Science.gov (United States)

    Ng, Tse Nga; Schwartz, David E.; Lavery, Leah L.; Whiting, Gregory L.; Russo, Beverly; Krusor, Brent; Veres, Janos; Bröms, Per; Herlogsson, Lars; Alam, Naveed; Hagel, Olle; Nilsson, Jakob; Karlsson, Christer

    2012-01-01

    Scalable circuits of organic logic and memory are realized using all-additive printing processes. A 3-bit organic complementary decoder is fabricated and used to read and write non-volatile, rewritable ferroelectric memory. The decoder-memory array is patterned by inkjet and gravure printing on flexible plastics. Simulation models for the organic transistors are developed, enabling circuit designs tolerant of the variations in printed devices. We explain the key design rules in fabrication of complex printed circuits and elucidate the performance requirements of materials and devices for reliable organic digital logic. PMID:22900143

  12. Scalable printed electronics: an organic decoder addressing ferroelectric non-volatile memory.

    Science.gov (United States)

    Ng, Tse Nga; Schwartz, David E; Lavery, Leah L; Whiting, Gregory L; Russo, Beverly; Krusor, Brent; Veres, Janos; Bröms, Per; Herlogsson, Lars; Alam, Naveed; Hagel, Olle; Nilsson, Jakob; Karlsson, Christer

    2012-01-01

    Scalable circuits of organic logic and memory are realized using all-additive printing processes. A 3-bit organic complementary decoder is fabricated and used to read and write non-volatile, rewritable ferroelectric memory. The decoder-memory array is patterned by inkjet and gravure printing on flexible plastics. Simulation models for the organic transistors are developed, enabling circuit designs tolerant of the variations in printed devices. We explain the key design rules in fabrication of complex printed circuits and elucidate the performance requirements of materials and devices for reliable organic digital logic.

  13. Exponential Smoothing, Long Memory and Volatility Prediction

    DEFF Research Database (Denmark)

    Proietti, Tommaso

    Extracting and forecasting the volatility of financial markets is an important empirical problem. The paper provides a time series characterization of the volatility components arising when the volatility process is fractionally integrated, and proposes a new predictor that can be seen as extensi...... methods for forecasting realized volatility, and that the estimated model confidence sets include the newly proposed fractional lag predictor in all occurrences....

  14. Peroxide induced volatile and non-volatile switching behavior in ZnO-based electrochemical metallization memory cell

    Science.gov (United States)

    Mangasa Simanjuntak, Firman; Chandrasekaran, Sridhar; Pattanayak, Bhaskar; Lin, Chun-Chieh; Tseng, Tseung-Yuen

    2017-09-01

    We explore the use of cubic-zinc peroxide (ZnO2) as a switching material for electrochemical metallization memory (ECM) cell. The ZnO2 was synthesized with a simple peroxide surface treatment. Devices made without surface treatment exhibits a high leakage current due to the self-doped nature of the hexagonal-ZnO material. Thus, its switching behavior can only be observed when a very high current compliance is employed. The synthetic ZnO2 layer provides a sufficient resistivity to the Cu/ZnO2/ZnO/ITO devices. The high resistivity of ZnO2 encourages the formation of a conducting bridge to activate the switching behavior at a lower operation current. Volatile and non-volatile switching behaviors with sufficient endurance and an adequate memory window are observed in the surface-treated devices. The room temperature retention of more than 104 s confirms the non-volatility behavior of the devices. In addition, our proposed device structure is able to work at a lower operation current among other reported ZnO-based ECM cells.

  15. High-performance non-volatile organic ferroelectric memory on banknotes

    KAUST Repository

    Khan, Mohammad A.

    2012-03-21

    High-performance non-volatile polymer ferroelectric memory are fabricated on banknotes using poly(vinylidene fluoride trifluoroethylene). The devices show excellent performance with high remnant polarization, low operating voltages, low leakage, high mobility, and long retention times. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Forced Ion Migration for Chalcogenide Phase Change Memory Device

    Science.gov (United States)

    Campbell, Kristy A (Inventor)

    2013-01-01

    Non-volatile memory devices with two stacked layers of chalcogenide materials comprising the active memory device have been investigated for their potential as phase-change memories. The devices tested included GeTe/SnTe, Ge2Se3/SnTe, and Ge2Se3/SnSe stacks. All devices exhibited resistance switching behavior. The polarity of the applied voltage with respect to the SnTe or SnSe layer was critical to the memory switching properties, due to the electric field induced movement of either Sn or Te into the Ge-chalcogenide layer. One embodiment of the invention is a device comprising a stack of chalcogenide-containing layers which exhibit phase-change switching only after a reverse polarity voltage potential is applied across the stack causing ion movement into an adjacent layer and thus "activating" the device to act as a phase-change random access memory device or a reconfigurable electronics device when the applied voltage potential is returned to the normal polarity. Another embodiment of the invention is a device that is capable of exhibiting more than two data states.

  17. A review of emerging non-volatile memory (NVM) technologies and applications

    Science.gov (United States)

    Chen, An

    2016-11-01

    This paper will review emerging non-volatile memory (NVM) technologies, with the focus on phase change memory (PCM), spin-transfer-torque random-access-memory (STTRAM), resistive random-access-memory (RRAM), and ferroelectric field-effect-transistor (FeFET) memory. These promising NVM devices are evaluated in terms of their advantages, challenges, and applications. Their performance is compared based on reported parameters of major industrial test chips. Memory selector devices and cell structures are discussed. Changing market trends toward low power (e.g., mobile, IoT) and data-centric applications create opportunities for emerging NVMs. High-performance and low-cost emerging NVMs may simplify memory hierarchy, introduce non-volatility in logic gates and circuits, reduce system power, and enable novel architectures. Storage-class memory (SCM) based on high-density NVMs could fill the performance and density gap between memory and storage. Some unique characteristics of emerging NVMs can be utilized for novel applications beyond the memory space, e.g., neuromorphic computing, hardware security, etc. In the beyond-CMOS era, emerging NVMs have the potential to fulfill more important functions and enable more efficient, intelligent, and secure computing systems.

  18. Bias-reduced estimation of long memory stochastic volatility

    DEFF Research Database (Denmark)

    Frederiksen, Per; Nielsen, Morten Ørregaard

    We propose to use a variant of the local polynomial Whittle estimator to estimate the memory parameter in volatility for long memory stochastic volatility models with potential nonstation- arity in the volatility process. We show that the estimator is asymptotically normal and capable of obtaining...... bias reduction as well as a rate of convergence arbitrarily close to the parametric rate, n1=2. A Monte Carlo study is conducted to support the theoretical results, and an analysis of daily exchange rates demonstrates the empirical usefulness of the estimators....

  19. Estimating and Forecasting Generalized Fractional Long Memory Stochastic Volatility Models

    NARCIS (Netherlands)

    S. Peiris (Shelton); M. Asai (Manabu); M.J. McAleer (Michael)

    2016-01-01

    textabstractIn recent years fractionally differenced processes have received a great deal of attention due to its flexibility in financial applications with long memory. This paper considers a class of models generated by Gegenbauer polynomials, incorporating the long memory in stochastic volatility

  20. Organic nonvolatile memory devices based on ferroelectricity

    NARCIS (Netherlands)

    Naber, R.C.G.; Asadi, K.; Blom, P.W.M.; Leeuw, D.M. de; Boer, B. de

    2010-01-01

    A memory functionality is a prerequisite for many applications of electronic devices. Organic nonvolatile memory devices based on ferroelectricity are a promising approach toward the development of a low-cost memory technology. In this Review Article we discuss the latest developments in this area w

  1. Organic Nonvolatile Memory Devices Based on Ferroelectricity

    NARCIS (Netherlands)

    Naber, Ronald C. G.; Asadi, Kamal; Blom, Paul W. M.; de Leeuw, Dago M.; de Boer, Bert

    2010-01-01

    A memory functionality is a prerequisite for many applications of electronic devices. Organic nonvolatile memory devices based on ferroelectricity are a promising approach toward the development of a low-cost memory technology. In this Review Article we discuss the latest developments in this area w

  2. Spirocyclic aromatic hydrocarbon-based organic nanosheets for eco-friendly aqueous processed thin-film non-volatile memory devices.

    Science.gov (United States)

    Lin, Zong-Qiong; Liang, Jin; Sun, Peng-Ju; Liu, Feng; Tay, Yee-Yan; Yi, Ming-Dong; Peng, Kun; Xia, Xian-Hai; Xie, Ling-Hai; Zhou, Xin-Hui; Zhao, Jian-Feng; Huang, Wei

    2013-07-19

    Supramolecular steric hindrance designs make pyrene-functionalized spiro[fluorene-9,7'-dibenzo[c,h]acridine]-5'-one (Py-SFDBAO) assemble into 2D nanostructures that facilitate aqueous phase large-area synthesis of high-quality and uniform crystalline thin films. Thin-film diodes using aqueous nanosheets as active layers exhibit a non-volatile bistable electrical switching feature with ON/OFF ratios of 6.0 × 10(4) and photoswitching with conductive gains of 10(2) -10(3). Organic nanosheets are potentially key components for eco-friendly aqueous dispersed organic nano-inks in the application of printed and flexible electronics.

  3. Robust Shared Objects for Non-Volatile Main Memory

    OpenAIRE

    Berryhill, Ryan; Golab, Wojciech; Tripunitara, Mahesh

    2016-01-01

    Research in concurrent in-memory data structures has focused almost exclusively on models where processes are either reliable, or may fail by crashing permanently. The case where processes may recover from failures has received little attention because recovery from conventional volatile memory is impossible in the event of a system crash, during which both the state of main memory and the private states of processes are lost. Future hardware architectures are likely to include various forms ...

  4. Active non-volatile memory post-processing

    Energy Technology Data Exchange (ETDEWEB)

    Kannan, Sudarsun; Milojicic, Dejan S.; Talwar, Vanish

    2017-04-11

    A computing node includes an active Non-Volatile Random Access Memory (NVRAM) component which includes memory and a sub-processor component. The memory is to store data chunks received from a processor core, the data chunks comprising metadata indicating a type of post-processing to be performed on data within the data chunks. The sub-processor component is to perform post-processing of said data chunks based on said metadata.

  5. Active non-volatile memory post-processing

    Science.gov (United States)

    Kannan, Sudarsun; Milojicic, Dejan S.; Talwar, Vanish

    2017-04-11

    A computing node includes an active Non-Volatile Random Access Memory (NVRAM) component which includes memory and a sub-processor component. The memory is to store data chunks received from a processor core, the data chunks comprising metadata indicating a type of post-processing to be performed on data within the data chunks. The sub-processor component is to perform post-processing of said data chunks based on said metadata.

  6. Design exploration of emerging nano-scale non-volatile memory

    CERN Document Server

    Yu, Hao

    2014-01-01

    This book presents the latest techniques for characterization, modeling and design for nano-scale non-volatile memory (NVM) devices.  Coverage focuses on fundamental NVM device fabrication and characterization, internal state identification of memristic dynamics with physics modeling, NVM circuit design, and hybrid NVM memory system design-space optimization. The authors discuss design methodologies for nano-scale NVM devices from a circuits/systems perspective, including the general foundations for the fundamental memristic dynamics in NVM devices.  Coverage includes physical modeling, as well as the development of a platform to explore novel hybrid CMOS and NVM circuit and system design.   • Offers readers a systematic and comprehensive treatment of emerging nano-scale non-volatile memory (NVM) devices; • Focuses on the internal state of NVM memristic dynamics, novel NVM readout and memory cell circuit design, and hybrid NVM memory system optimization; • Provides both theoretical analysis and pr...

  7. Long Memory in Stock Market Volatility and the Volatility-in-Mean Effect: The FIEGARCH-M Model

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper; Nielsen, Morten Ørregaard; Zhu, Jie

    We extend the fractionally integrated exponential GARCH (FIEGARCH) model for daily stock return data with long memory in return volatility of Bollerslev and Mikkelsen (1996) by introducing a possible volatility-in-mean effect. To avoid that the long memory property of volatility carries over to r...

  8. Long Memory in Stock Market Volatility and the Volatility-in-Mean Effect: The FIEGARCH-M Model

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper; Nielsen, Morten Ørregaard; Zhu, Jie

    We extend the fractionally integrated exponential GARCH (FIEGARCH) model for daily stock return data with long memory in return volatility of Bollerslev and Mikkelsen (1996) by introducing a possible volatility-in-mean effect. To avoid that the long memory property of volatility carries over to r...

  9. An Intelligent Analysis Model for Multisource Volatile Memory

    Directory of Open Access Journals (Sweden)

    Xiaolu Zhang

    2013-09-01

    Full Text Available For the rapidly development of network and distributed computing environment, it make researchers harder to do analysis examines only from one or few pieces of data source in persistent data-oriented approaches, so as the volatile memory analysis either. Therefore, mass data automatically analysis and action modeling needs to be considered for reporting entire network attack process. To model multiple volatile data sources situation can help understand and describe both thinking process of investigator and possible action step for attacker. This paper presents a Game model for multisource volatile data and applies it to main memory images analysis with the definition of space-time feature for volatile element information. Abstract modeling allows the lessons gleaned in performing intelligent analysis, evidence filing and automating presentation. Finally, a test demo based on the model is also present to illustrate the whole procedure

  10. Models for Total-Dose Radiation Effects in Non-Volatile Memory

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Philip Montgomery; Wix, Steven D.

    2017-04-01

    The objective of this work is to develop models to predict radiation effects in non- volatile memory: flash memory and ferroelectric RAM. In flash memory experiments have found that the internal high-voltage generators (charge pumps) are the most sensitive to radiation damage. Models are presented for radiation effects in charge pumps that demonstrate the experimental results. Floating gate models are developed for the memory cell in two types of flash memory devices by Intel and Samsung. These models utilize Fowler-Nordheim tunneling and hot electron injection to charge and erase the floating gate. Erase times are calculated from the models and compared with experimental results for different radiation doses. FRAM is less sensitive to radiation than flash memory, but measurements show that above 100 Krad FRAM suffers from a large increase in leakage current. A model for this effect is developed which compares closely with the measurements.

  11. Long Memory in STOCK Market Volatility: the International Evidence

    Science.gov (United States)

    Yang, Chunxia; Hu, Sen; Xia, Bingying; Wang, Rui

    2012-08-01

    It is still a hot topic to catch the auto-dependence behavior of volatility. Here, based on the measurement of average volatility, under different observation window size, we investigated the dependence of successive volatility of several main stock indices and their simulated GARCH(1, 1) model, there were obvious linear auto-dependence in the logarithm of volatility under a small observation window size and nonlinear auto-dependence under a big observation. After calculating the correlation and mutual information of the logarithm of volatility for Dow Jones Industrial Average during different periods, we find that some influential events can change the correlation structure and the volatilities of different periods have distinct influence on that of the remote future. Besides, GARCH model could produce similar behavior of dependence as real data and long memory property. But our analyses show that the auto-dependence of volatility in GARCH is different from that in real data, and the long memory is undervalued by GARCH.

  12. Polymer and organic nonvolatile memory devices

    NARCIS (Netherlands)

    Heremans, P.; Gelinck, G.H.; Müller, R.; Baeg, K.J.; Kim, D.Y.; Noh, Y.Y.

    2011-01-01

    Organic molecules and semiconductors have been proposed as active part of a large variety of nonvolatile memory devices, including resistors, diodes and transistors. In this review, we focus on electrically reprogrammable nonvolatile memories. We classify several possible devices according to their

  13. Windows Volatile Memory Forensics Based on Correlation Analysis

    Directory of Open Access Journals (Sweden)

    Xiaolu Zhang

    2014-03-01

    Full Text Available In this paper, we present an integrated memory forensic solution for multiple Windows memory images. By calculation, the method can find out the correlation degree among the processes of volatile memory images and the hidden clues behind the events of computers, which is usually difficult to be obtained and easily ignored by analyzing one single memory image and forensic investigators. In order to test the validity, we performed an experiment based on two hosts' memory image which contains criminal incidents. According to the experimental result, we find that the event chains reconstructed by our method are similar to the actual actions in the criminal scene. Investigators can review the digital crime scenario which is contained in the data set by analyzing the experimental results. This paper is aimed at finding the valid actions with illegal attempt and making the memory analysis not to be utterly dependent on the operating system and relevant experts.

  14. Modelling Long Memory Volatility in Agricultural Commodity Futures Returns

    NARCIS (Netherlands)

    C-L. Chang (Chia-Lin); M.J. McAleer (Michael); R. Tansuchat (Roengchai)

    2012-01-01

    textabstractThis paper estimates a long memory volatility model for 16 agricultural commodity futures returns from different futures markets, namely corn, oats, soybeans, soybean meal, soybean oil, wheat, live cattle, cattle feeder, pork, cocoa, coffee, cotton, orange juice, Kansas City wheat, rubbe

  15. Modelling Long Memory Volatility in Agricultural Commodity Futures Returns

    NARCIS (Netherlands)

    R. Tansuchat (Roengchai); C-L. Chang (Chia-Lin); M.J. McAleer (Michael)

    2009-01-01

    textabstractThis paper estimates the long memory volatility model for 16 agricultural commodity futures returns from different futures markets, namely corn, oats, soybeans, soybean meal, soybean oil, wheat, live cattle, cattle feeder, pork, cocoa, coffee, cotton, orange juice, Kansas City wheat, rub

  16. Scaling and memory in the return intervals of realized volatility

    Science.gov (United States)

    Ren, Fei; Gu, Gao-Feng; Zhou, Wei-Xing

    2009-11-01

    We perform return interval analysis of 1-min realized volatility defined by the sum of absolute high-frequency intraday returns for the Shanghai Stock Exchange Composite Index (SSEC) and 22 constituent stocks of SSEC. The scaling behavior and memory effect of the return intervals between successive realized volatilities above a certain threshold q are carefully investigated. In comparison with the volatility defined by the closest tick prices to the minute marks, the return interval distribution for the realized volatility shows a better scaling behavior since 20 stocks (out of 22 stocks) and the SSEC pass the Kolmogorov-Smirnov (KS) test and exhibit scaling behaviors, among which the scaling function for 8 stocks could be approximated well by a stretched exponential distribution revealed by the KS goodness-of-fit test under the significance level of 5%. The improved scaling behavior is further confirmed by the relation between the fitted exponent γ and the threshold q. In addition, the similarity of the return interval distributions for different stocks is also observed for the realized volatility. The investigation of the conditional probability distribution and the detrended fluctuation analysis (DFA) show that both short-term and long-term memory exists in the return intervals of realized volatility.

  17. Low-power non-volatile spintronic memory: STT-RAM and beyond

    Science.gov (United States)

    Wang, K. L.; Alzate, J. G.; Khalili Amiri, P.

    2013-02-01

    The quest for novel low-dissipation devices is one of the most critical for the future of semiconductor technology and nano-systems. The development of a low-power, universal memory will enable a new paradigm of non-volatile computation. Here we consider STT-RAM as one of the emerging candidates for low-power non-volatile memory. We show different configurations for STT memory and demonstrate strategies to optimize key performance parameters such as switching current and energy. The energy and scaling limits of STT-RAM are discussed, leading us to argue that alternative writing mechanisms may be required to achieve ultralow power dissipation, a necessary condition for direct integration with CMOS at the gate level for non-volatile logic purposes. As an example, we discuss the use of the giant spin Hall effect as a possible alternative to induce magnetization reversal in magnetic tunnel junctions using pure spin currents. Further, we concentrate on magnetoelectric effects, where electric fields are used instead of spin-polarized currents to manipulate the nanomagnets, as another candidate solution to address the challenges of energy efficiency and density. The possibility of an electric-field-controlled magnetoelectric RAM as a promising candidate for ultralow-power non-volatile memory is discussed in the light of experimental data demonstrating voltage-induced switching of the magnetization and reorientation of the magnetic easy axis by electric fields in nanomagnets.

  18. Shape memory polymer medical device

    Science.gov (United States)

    Maitland, Duncan; Benett, William J.; Bearinger, Jane P.; Wilson, Thomas S.; Small, IV, Ward; Schumann, Daniel L.; Jensen, Wayne A.; Ortega, Jason M.; Marion, III, John E.; Loge, Jeffrey M.

    2010-06-29

    A system for removing matter from a conduit. The system includes the steps of passing a transport vehicle and a shape memory polymer material through the conduit, transmitting energy to the shape memory polymer material for moving the shape memory polymer material from a first shape to a second and different shape, and withdrawing the transport vehicle and the shape memory polymer material through the conduit carrying the matter.

  19. Integrated photonics with programmable non-volatile memory

    Science.gov (United States)

    Song, Jun-Feng; Luo, Xian-Shu; Lim, Andy Eu-Jin; Li, Chao; Fang, Qing; Liow, Tsung-Yang; Jia, Lian-Xi; Tu, Xiao-Guang; Huang, Ying; Zhou, Hai-Feng; Lo, Guo-Qiang

    2016-03-01

    Silicon photonics integrated circuits (Si-PIC) with well-established active and passive building elements are progressing towards large-scale commercialization in optical communications and high speed optical interconnects applications. However, current Si-PICs do not have memory capabilities, in particular, the non-volatile memory functionality for energy efficient data storage. Here, we propose an electrically programmable, multi-level non-volatile photonics memory cell (PMC) fabricated by standard complementary-metal-oxide-semiconductor (CMOS) compatible processes. A micro-ring resonator (MRR) was built using the PMC to optically read the memory states. Switching energy smaller than 20 pJ was achieved. Additionally, a MRR memory array was employed to demonstrate a four-bit memory read capacity. Theoretically, this can be increased up to ~400 times using a 100 nm free spectral range broadband light source. The fundamental concept of this design provides a route to eliminate the von Neumann bottleneck. The energy-efficient optical storage can complement on-chip optical interconnects for neutral networking, memory input/output interfaces and other computational intensive applications.

  20. Projected phase-change memory devices

    Science.gov (United States)

    Koelmans, Wabe W.; Sebastian, Abu; Jonnalagadda, Vara Prasad; Krebs, Daniel; Dellmann, Laurent; Eleftheriou, Evangelos

    2015-09-01

    Nanoscale memory devices, whose resistance depends on the history of the electric signals applied, could become critical building blocks in new computing paradigms, such as brain-inspired computing and memcomputing. However, there are key challenges to overcome, such as the high programming power required, noise and resistance drift. Here, to address these, we present the concept of a projected memory device, whose distinguishing feature is that the physical mechanism of resistance storage is decoupled from the information-retrieval process. We designed and fabricated projected memory devices based on the phase-change storage mechanism and convincingly demonstrate the concept through detailed experimentation, supported by extensive modelling and finite-element simulations. The projected memory devices exhibit remarkably low drift and excellent noise performance. We also demonstrate active control and customization of the programming characteristics of the device that reliably realize a multitude of resistance states.

  1. Lateral electric-field-driven non-volatile four-state memory in multiferroic heterostructures

    Science.gov (United States)

    Zhou, Cai; Zhang, Chao; Yao, Jinli; Jiang, Changjun

    2016-09-01

    A non-volatile four-state memory is formed using an in-plane side-polarization configuration in a Co/(011) Pb(Mg1/3Nb2/3)O3-PbTiO3 (Co/PMN-PT) heterostructure. The resistivity vs. electric field behavior shows a change from volatile butterfly to looplike to non-volatile butterfly characteristics when the temperature decreases from 290 K to 83 K under an electric field of 10 kV/cm and then increases back to 290 K; this behavior is attributed to the strain-mediated magnetoelectric effect. In addition, the in-plane resistivity of Co film, which was measured using the four-probe technique, can be controlled both electrically and magnetically. Specifically, a non-volatile resistivity is gained by the application of electric field pulses. Additionally, a four-state memory is obtained by co-mediation of the magnetic field and electric field pulses, compared with the two different states achieved under the application of the electric field only, which indicates that our results are highly important for multi-state memory and spintronic devices applications.

  2. Review on Non-Volatile Memory with High-k Dielectrics: Flash for Generation Beyond 32 nm

    Directory of Open Access Journals (Sweden)

    Chun Zhao

    2014-07-01

    Full Text Available Flash memory is the most widely used non-volatile memory device nowadays. In order to keep up with the demand for increased memory capacities, flash memory has been continuously scaled to smaller and smaller dimensions. The main benefits of down-scaling cell size and increasing integration are that they enable lower manufacturing cost as well as higher performance. Charge trapping memory is regarded as one of the most promising flash memory technologies as further down-scaling continues. In addition, more and more exploration is investigated with high-k dielectrics implemented in the charge trapping memory. The paper reviews the advanced research status concerning charge trapping memory with high-k dielectrics for the performance improvement. Application of high-k dielectric as charge trapping layer, blocking layer, and tunneling layer is comprehensively discussed accordingly.

  3. Highly Stretchable Non-volatile Nylon Thread Memory

    Science.gov (United States)

    Kang, Ting-Kuo

    2016-04-01

    Integration of electronic elements into textiles, to afford e-textiles, can provide an ideal platform for the development of lightweight, thin, flexible, and stretchable e-textiles. This approach will enable us to meet the demands of the rapidly growing market of wearable-electronics on arbitrary non-conventional substrates. However the actual integration of the e-textiles that undergo mechanical deformations during both assembly and daily wear or satisfy the requirements of the low-end applications, remains a challenge. Resistive memory elements can also be fabricated onto a nylon thread (NT) for e-textile applications. In this study, a simple dip-and-dry process using graphene-PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) ink is proposed for the fabrication of a highly stretchable non-volatile NT memory. The NT memory appears to have typical write-once-read-many-times characteristics. The results show that an ON/OFF ratio of approximately 103 is maintained for a retention time of 106 s. Furthermore, a highly stretchable strain and a long-term digital-storage capability of the ON-OFF-ON states are demonstrated in the NT memory. The actual integration of the knitted NT memories into textiles will enable new design possibilities for low-cost and large-area e-textile memory applications.

  4. Combating Memory Corruption Attacks On Scada Devices

    Science.gov (United States)

    Bellettini, Carlo; Rrushi, Julian

    Memory corruption attacks on SCADA devices can cause significant disruptions to control systems and the industrial processes they operate. However, despite the presence of numerous memory corruption vulnerabilities, few, if any, techniques have been proposed for addressing the vulnerabilities or for combating memory corruption attacks. This paper describes a technique for defending against memory corruption attacks by enforcing logical boundaries between potentially hostile data and safe data in protected processes. The technique encrypts all input data using random keys; the encrypted data is stored in main memory and is decrypted according to the principle of least privilege just before it is processed by the CPU. The defensive technique affects the precision with which attackers can corrupt control data and pure data, protecting against code injection and arc injection attacks, and alleviating problems posed by the incomparability of mitigation techniques. An experimental evaluation involving the popular Modbus protocol demonstrates the feasibility and efficiency of the defensive technique.

  5. Resistively heated shape memory polymer device

    Energy Technology Data Exchange (ETDEWEB)

    Marion, III, John E.; Bearinger, Jane P.; Wilson, Thomas S.; Maitland, Duncan J.

    2017-09-05

    A resistively heated shape memory polymer device is made by providing a rod, sheet or substrate that includes a resistive medium. The rod, sheet or substrate is coated with a first shape memory polymer providing a coated intermediate unit. The coated intermediate unit is in turn coated with a conductive material providing a second intermediate unit. The second coated intermediate unit is in turn coated with an outer shape memory polymer. The rod, sheet or substrate is exposed and an electrical lead is attached to the rod, sheet or substrate. The conductive material is exposed and an electrical lead is attached to the conductive material.

  6. Resistively heated shape memory polymer device

    Science.gov (United States)

    Marion, III, John E.; Bearinger, Jane P.; Wilson, Thomas S.; Maitland, Duncan J.

    2016-10-25

    A resistively heated shape memory polymer device is made by providing a rod, sheet or substrate that includes a resistive medium. The rod, sheet or substrate is coated with a first shape memory polymer providing a coated intermediate unit. The coated intermediate unit is in turn coated with a conductive material providing a second intermediate unit. The second coated intermediate unit is in turn coated with an outer shape memory polymer. The rod, sheet or substrate is exposed and an electrical lead is attached to the rod, sheet or substrate. The conductive material is exposed and an electrical lead is attached to the conductive material.

  7. PREFACE: Emerging non-volatile memories: magnetic and resistive technologies Emerging non-volatile memories: magnetic and resistive technologies

    Science.gov (United States)

    Dieny, B.; Jagadish, Chennupati

    2013-02-01

    In 2010, the International Technology Roadmap for Semiconductors (ITRS) published an assessment of the potential and maturity of selected emerging research on memory technologies. Eight different technologies of non-volatile memories were compared (ferroelectric gate field-effect transistor, nano-electro-mechanical switch, spin-transfer torque random access memories (STTRAM), various types of resistive RAM, in particular redox RAM, nanothermal phase change RAM, electronic effects RAM, macromolecular memories and molecular RAM). In this report, spin-transfer torque MRAM and redox RRAM were identified as two emerging memory technologies recommended for accelerated research and development leading to scaling and commercialization of non-volatile RAM to and beyond the 16nm generation. Nowadays, there is an intense research and development effort in microelectronics on these two technologies, one based on spintronic phenomena (tunnel magnetoresistance and spin-transfer torque), the other based on migration of vacancies or ions in an insulating matrix driven by oxydo-reduction potentials. Both technologies could be used for standalone or embedded applications. In this context, it appeared timely to publish a cluster of review articles related to these two technologies. In this cluster, the first two articles introduce the general principles of spin-transfer torque RAM and of thermally assisted RAM. The third presents a broader range of applications for this integrated CMOS/magnetic tunnel junction technology for low-power electronics. The fourth paper presents more advanced research on voltage control of magnetization switching with the aim of dramatically reducing the write energy in MRAM. The last two papers deal with two categories of resistive RAM, one based on the migration of cations, the other one based on nanowires. We thank all the authors and reviewers for their contribution to this cluster issue. Our special thanks are due to Dr Olivia Roche, Publisher, and Dr

  8. Integration of organic based Schottky junctions for crossbar non-volatile memory applications

    DEFF Research Database (Denmark)

    Katsia, E.; Tallarida, G.; Ferrari, S.

    2008-01-01

    Small size Schottky junctions using two different synthesized organic semiconductors (oligophenylene-vinylenes) were integrated by standard UV lithography into crossbar arrays. The proposed integration scheme can be applied to a wide class of organics without affecting material properties. Current......-voltage characteristics were studied in order to investigate which of the tested compounds could possibly reach the requirements for non-volatile memory applications. All the investigated devices displayed good rectifying properties, ranging from 10(2) to 10(4). On the other hand, one of the compounds reveals higher...

  9. An Overview of Non-Volatile Flip-Flops Based on Emerging Memory Technologies An Overview of Non-Volatile Flip-Flops Based on Emerging Memory Technologies

    Institute of Scientific and Technical Information of China (English)

    J. M. Portal; C. Chappert; W.-S. Zhao; M. Bocquet; M. Moreau; H. Aziza; D. Deleruyelle; Y. Zhang; W. Kang; J.-O. Klein; Y.-G. Zhang

    2014-01-01

    Low power consumption is a major issue in nowadays electronics systems. This trend is pushed by the development of data center related to cloud services and soon to the Internet of Things (IoT) deployment. Memories are one of the major contributors to power consumption. However, the development of emerging memory technologies paves the way to low-power design, through the partial replacement of the dynamic random access memory (DRAM) with the non-volatile stand-alone memory in servers or with the embedded or distributed emerging non-volatile memory in IoT objects. In the latter case, non-volatile flip-flops (NVFFs) seem a promising candidate to replace the retention latch. Indeed, IoT objects present long sleep time and NVFFs offer to save data in registers with zero power when the application is idle. This paper gives an overview of NVFF architecture flavors for various emerging memory technologies.

  10. Fabrication and electrical characterization of a MOS memory device containing self-assembled metallic nanoparticles

    Science.gov (United States)

    Sargentis, Ch.; Giannakopoulos, K.; Travlos, A.; Tsamakis, D.

    2007-04-01

    Floating gate devices with nanoparticles embedded in dielectrics have recently attracted much attention due to the fact that these devices operate as non-volatile memories with high speed, high density and low power consumption. In this paper, memory devices containing gold (Au) nanoparticles have been fabricated using e-gun evaporation. The Au nanoparticles are deposited on a very thin SiO 2 layer and are then fully covered by a HfO 2 layer. The HfO 2 is a high- k dielectric and gives good scalability to the fabricated devices. We studied the effect of the deposition parameters to the size and the shape of the Au nanoparticles using capacitance-voltage and conductance-voltage measurements, we demonstrated that the fabricated device can indeed operate as a low-voltage memory device.

  11. Malware Memory Analysis of the IVYL Linux Rootkit: Investigating a Publicly Available Linux Rootkit Using the Volatility Memory Analysis Framework

    Science.gov (United States)

    2015-04-01

    Malware memory analysis of the IVYL Linux rootkit Investigating a publicly available Linux rootkit using the Volatility memory analysis...Abstract …….. This report is the second in a series that will examine Linux Volatility-specific memory malware-based analysis techniques...described therein are not applicable to Linux -based analyses including data carving and anti-virus scanning. Thus, with minimal use of scanner-based

  12. The properties and mechanism of long-term memory in nonparametric volatility

    Science.gov (United States)

    Li, Handong; Cao, Shi-Nan; Wang, Yan

    2010-08-01

    Recent empirical literature documents the presence of long-term memory in return volatility. But the mechanism of the existence of long-term memory is still unclear. In this paper, we investigate the origin and properties of long-term memory with nonparametric volatility, using high-frequency time series data of the Chinese Shanghai Composite Stock Price Index. We perform Detrended Fluctuation Analysis (DFA) on three different nonparametric volatility estimators with different sampling frequencies. For the same volatility series, the Hurst exponents reduce as the sampling time interval increases, but they are still larger than 1/2, which means that no matter how the interval changes, it still cannot change the existence of long memory. RRV presents a relatively stable property on long-term memory and is less influenced by sampling frequency. RV and RBV have some evolutionary trends depending on time intervals, which indicating that the jump component has no significant impact on the long-term memory property. This suggests that the presence of long-term memory in nonparametric volatility can be contributed to the integrated variance component. Considering the impact of microstructure noise, RBV and RRV still present long-term memory under various time intervals. We can infer that the presence of long-term memory in realized volatility is not affected by market microstructure noise. Our findings imply that the long-term memory phenomenon is an inherent characteristic of the data generating process, not a result of microstructure noise or volatility clustering.

  13. Control devices incorporated with shape memory alloy

    Institute of Scientific and Technical Information of China (English)

    Xue Suduo; Li Xiongyan

    2007-01-01

    Shape Memory Alloy (SMA) is a type of material that offers some unique characteristics for use in devices for vibration control applications. Based on SMA's material properties, four types of control devices that incorporate NiTi SMA wires are introduced in this paper, which include three types of dampers (SMA damper, SMA-MR damper and SMA-friction damper) and one kind of isolation bearing (SMA-rubber bearing). Mechanical models of these devices and their experimental verifications are presented. To investigate the control performance of these devices, the SMA-MR damper and SMA-rubber bearing are applied to structures. The results show that the control devices could be effective in reducing the seismic response of structures.

  14. Low-cost and nanoscale non-volatile memory concept for future silicon chips

    NARCIS (Netherlands)

    Lankhorst, M.H.R.; Ketelaars, B.W.S.M.M.; Wolters, R.A.M.

    2005-01-01

    Non-volatile 'flash' memories are key components of integrated circuits because they retain their data when power is interrupted. Despite their great commercial success, the semiconductor industry is searching for alternative non-volatile memories with improved performance and better opportunities f

  15. Shape Memory Polymer Therapeutic Devices for Stroke

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, T S; Small IV, W; Benett, W J; Bearinger, J P; Maitland, D J

    2005-10-11

    Shape memory polymers (SMPs) are attracting a great deal of interest in the scientific community for their use in applications ranging from light weight structures in space to micro-actuators in MEMS devices. These relatively new materials can be formed into a primary shape, reformed into a stable secondary shape, and then controllably actuated to recover their primary shape. The first part of this presentation will be a brief review of the types of polymeric structures which give rise to shape memory behavior in the context of new shape memory polymers with highly regular network structures recently developed at LLNL for biomedical devices. These new urethane SMPs have improved optical and physical properties relative to commercial SMPs, including improved clarity, high actuation force, and sharper actuation transition. In the second part of the presentation we discuss the development of SMP based devices for mechanically removing neurovascular occlusions which result in ischemic stroke. These devices are delivered to the site of the occlusion in compressed form, are pushed through the occlusion, actuated (usually optically) to take on an expanded conformation, and then used to dislodge and grip the thrombus while it is withdrawn through the catheter.

  16. Investigation of High-k Dielectrics and Metal Gate Electrodes for Non-volatile Memory Applications

    Science.gov (United States)

    Jayanti, Srikant

    Due to the increasing demand of non-volatile flash memories in the portable electronics, the device structures need to be scaled down drastically. However, the scalability of traditional floating gate structures beyond 20 nm NAND flash technology node is uncertain. In this regard, the use of metal gates and high-k dielectrics as the gate and interpoly dielectrics respectively, seem to be promising substitutes in order to continue the flash scaling beyond 20nm. Furthermore, research of novel memory structures to overcome the scaling challenges need to be explored. Through this work, the use of high-k dielectrics as IPDs in a memory structure has been studied. For this purpose, IPD process optimization and barrier engineering were explored to determine and improve the memory performance. Specifically, the concept of high-k / low-k barrier engineering was studied in corroboration with simulations. In addition, a novel memory structure comprising a continuous metal floating gate was investigated in combination with high-k blocking oxides. Integration of thin metal FGs and high-k dielectrics into a dual floating gate memory structure to result in both volatile and non-volatile modes of operation has been demonstrated, for plausible application in future unified memory architectures. The electrical characterization was performed on simple MIS/MIM and memory capacitors, fabricated through CMOS compatible processes. Various analytical characterization techniques were done to gain more insight into the material behavior of the layers in the device structure. In the first part of this study, interfacial engineering was investigated by exploring La2O3 as SiO2 scavenging layer. Through the silicate formation, the consumption of low-k SiO2 was controlled and resulted in a significant improvement in dielectric leakage. The performance improvement was also gauged through memory capacitors. In the second part of the study, a novel memory structure consisting of continuous metal FG

  17. Flexible organic memory devices with multilayer graphene electrodes.

    Science.gov (United States)

    Ji, Yongsung; Lee, Sangchul; Cho, Byungjin; Song, Sunghoon; Lee, Takhee

    2011-07-26

    We fabricated 8 × 8 cross-bar array-type flexible organic resistive memory devices with transparent multilayer graphene (MLG) electrodes on a poly(ethylene terephthalate) substrate. The active layer of the memory devices is a composite of polyimide and 6-phenyl-C61 butyric acid methyl ester. The sheet resistance of the MLG film on memory device was found to be ∼270 Ω/◻, and the transmittance of separated MLG film from memory device was ∼92%. The memory devices showed typical write-once-read-many (WORM) characteristics and an ON/OFF ratio of over ∼10(6). The memory devices also exhibited outstanding cell-to-cell uniformity with flexibility. There was no substantial variation observed in the current levels of the WORM memory devices upon bending and bending cycling up to 10 000 times. A retention time of over 10(4) s was observed without fluctuation under bending.

  18. In-Plane Bistable Nanowire For Memory Devices

    CERN Document Server

    Charlot, B; Yamashita, K; Fujita, H; Toshiyoshi, H

    2008-01-01

    We present a nanomechanical device design to be used in a non-volatile mechanical memory point. The structure is composed of a suspended slender nanowire (width : 100nm, thickness 430nm length : 8 to 30$\\mu$m) clamped at its both ends. Electrodes are placed on each sides of the nanowire and are used to actuate the structure (writing, erasing) and to measure the position through a capactive bridge (reading). The structure is patterned by electron beam lithography on a pre-stressed thermally grown silicon dioxide layer. When later released, the stressed material relaxes and the beam buckles in a position of lower energy. Such symmetric beams, called Euler beams, show two stable deformed positions thus form a bistable structure. This paper will present the fabrication, simulation and mechanical and electrical actuation of an in plane bistable nanowire. Final paper will include a section on FEM simulations.

  19. The Effect of Long Memory in Volatility on Stock Market Fluctuations

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper; Nielsen, Morten Ørregaard

    2007-01-01

    Recent empirical evidence demonstrates the presence of an important long memory component in realized asset return volatility. We specify and estimate multivariate models for the joint dynamics of stock returns and volatility that allow for long memory in volatility without imposing this property...... on returns. Asset pricing theory imposes testable cross-equation restrictions on the system that are not rejected in our preferred specifications, which include a strong financial leverage effect. We show that the impact of volatility shocks on stock prices is small and short-lived, in spite of a positive...

  20. The Effect of Long Memory in Volatility on Stock Market Fluctuations

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper; Nielsen, Morten Ørregaard

    Recent empirical evidence demonstrates the presence of an important long memory component in realized asset return volatility. We specify and estimate multivariate models for the joint dynamics of stock returns and volatility that allow for long memory in volatility without imposing this property...... on returns. Asset pricing theory imposes testable cross-equation restrictions on the system that are not rejected in our preferred specifications, which include a strong financial leverage effect. We show that the impact of volatility shocks on stock prices is small and short-lived, in spite of a positive...

  1. Polymer ferroelectric field-effect memory device with SnO channel layer exhibits record hole mobility

    KAUST Repository

    Caraveo-Frescas, J. A.

    2014-06-10

    Here we report for the first time a hybrid p-channel polymer ferroelectric field-effect transistor memory device with record mobility. The memory device, fabricated at 200C on both plastic polyimide and glass substrates, uses ferroelectric polymer P(VDF-TrFE) as the gate dielectric and transparent p-type oxide (SnO) as the active channel layer. A record mobility of 3.3 cm 2V-1s-1, large memory window (~16 V), low read voltages (~-1 V), and excellent retention characteristics up to 5000 sec have been achieved. The mobility achieved in our devices is over 10 times higher than previously reported polymer ferroelectric field-effect transistor memory with p-type channel. This demonstration opens the door for the development of non-volatile memory devices based on dual channel for emerging transparent and flexible electronic devices.

  2. Polymer ferroelectric field-effect memory device with SnO channel layer exhibits record hole mobility

    Science.gov (United States)

    Caraveo-Frescas, J. A.; Khan, M. A.; Alshareef, H. N.

    2014-06-01

    Here we report for the first time a hybrid p-channel polymer ferroelectric field-effect transistor memory device with record mobility. The memory device, fabricated at 200°C on both plastic polyimide and glass substrates, uses ferroelectric polymer P(VDF-TrFE) as the gate dielectric and transparent p-type oxide (SnO) as the active channel layer. A record mobility of 3.3 cm2V-1s-1, large memory window (~16 V), low read voltages (~-1 V), and excellent retention characteristics up to 5000 sec have been achieved. The mobility achieved in our devices is over 10 times higher than previously reported polymer ferroelectric field-effect transistor memory with p-type channel. This demonstration opens the door for the development of non-volatile memory devices based on dual channel for emerging transparent and flexible electronic devices.

  3. Organic bistable memory devices based on MoO3 nanoparticle embedded Alq3 structures

    Science.gov (United States)

    Abhijith, T.; Kumar, T. V. Arun; Reddy, V. S.

    2017-03-01

    Organic bistable memory devices were fabricated by embedding a thin layer of molybdenum trioxide (MoO3) between two tris-(8-hydroxyquinoline)aluminum (Alq3) layers. The device exhibited excellent switching characteristics with an ON/OFF current ratio of 1.15 × 103 at a read voltage of 1 V. The device showed repeatable write–erase capability and good stability in both the conductance states. These conductance states are non-volatile in nature and can be obtained by applying appropriate voltage pulses. The effect of MoO3 layer thickness and its location in the Alq3 matrix on characteristics of the memory device was investigated. The field emission scanning electron microscopy (FE-SEM) images of the MoO3 layer revealed the presence of isolated nanoparticles. Based on the experimental results, a mechanism has been proposed for explaining the conductance switching of fabricated devices.

  4. Rad Hard Non Volatile Memory for FPGA BootLoading Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Radiation-hardened non volatile memory (NVM) is needed to store the golden copy of the image(s) has not kept pace with the advances in FPGAs. Consider that a single...

  5. Radiation Hardened Nanobridge based Non-volatile Memory for Space Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This NASA Phase I SBIR program would develop and demonstrate radiation hardened nanobridge based non-volatile memory (NVM) for space applications. Specifically, we...

  6. Long-term Memory and Volatility Clustering in Daily and High-frequency Price Changes

    CERN Document Server

    Oh, G J; Um, C J; Kim, Seunghwann; Oh, GabJin; Um, Cheol-Jun

    2006-01-01

    We study the long-term memory in diverse stock market indices and foreign exchange rates using the Detrended Fluctuation Analysis(DFA). For all daily and high-frequency market data studied, no significant long-term memory property is detected in the return series, while a strong long-term memory property is found in the volatility time series. The possible causes of the long-term memory property are investigated using the return data filtered by the AR(1) model, reflecting the short-term memory property, and the GARCH(1,1) model, reflecting the volatility clustering property, respectively. Notably, we found that the memory effect in the AR(1) filtered return and volatility time series remains unchanged, while the long-term memory property either disappeared or diminished significantly in the volatility series of the GARCH(1,1) filtered data. We also found that in the high-frequency data the long-term memory property may be generated by the volatility clustering as well as higher autocorrelation. Our results i...

  7. The Effect of Long Memory in Volatility on Stock Market Fluctuations

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper; Nielsen, Morten Ørregaard

    on returns. Asset pricing theory imposes testable cross- equation restrictions on the system that are not rejected in our preferred specifications, which include a strong financial leverage effect. We show that the impact of volatility shocks on stock prices is small and short-lived, in spite of a positive...... risk-return trade-off and long memory in volatility....

  8. A hybrid magnetic/complementary metal oxide semiconductor three-context memory bit cell for non-volatile circuit design

    Science.gov (United States)

    Jovanović, B.; Brum, R. M.; Torres, L.

    2014-04-01

    After decades of continued scaling to the beat of Moore's law, it now appears that conventional silicon based devices are approaching their physical limits. In today's deep-submicron nodes, a number of short-channel and quantum effects are emerging that affect the manufacturing process, as well as, the functionality of the microelectronic systems-on-chip. Spintronics devices that exploit both the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge, are promising solutions to circumvent these scaling threats. Being compatible with the CMOS technology, such devices offer a promising synergy of radiation immunity, infinite endurance, non-volatility, increased density, etc. In this paper, we present a hybrid (magnetic/CMOS) cell that is able to store and process data both electrically and magnetically. The cell is based on perpendicular spin-transfer torque magnetic tunnel junctions (STT-MTJs) and is suitable for use in magnetic random access memories and reprogrammable computing (non-volatile registers, processor cache memories, magnetic field-programmable gate arrays, etc). To demonstrate the potential our hybrid cell, we physically implemented a small hybrid memory block using 45 nm × 45 nm round MTJs for the magnetic part and 28 nm fully depleted silicon on insulator (FD-SOI) technology for the CMOS part. We also report the cells measured performances in terms of area, robustness, read/write speed and energy consumption.

  9. Microwave impedance imaging on semiconductor memory devices

    Science.gov (United States)

    Kundhikanjana, Worasom; Lai, Keji; Yang, Yongliang; Kelly, Michael; Shen, Zhi-Xun

    2011-03-01

    Microwave impedance microscopy (MIM) maps out the real and imaginary components of the tip-sample impedance, from which the local conductivity and dielectric constant distribution can be derived. The stray field contribution is minimized in our shielded cantilever design, enabling quantitative analysis of nano-materials and device structures. We demonstrate here that the MIM can spatially resolve the conductivity variation in a dynamic random access memory (DRAM) sample. With DC or low-frequency AC bias applied to the tip, contrast between n-doped and p-doped regions in the dC/dV images is observed, and p-n junctions are highlighted in the dR/dV images. The results can be directly compared with data taken by scanning capacitance microscope (SCM), which uses unshielded cantilevers and resonant electronics, and the MIM reveals more information of the local dopant concentration than SCM.

  10. Reduced graphene oxide based flexible organic charge trap memory devices

    Science.gov (United States)

    Rani, Adila; Song, Ji-Min; Jung Lee, Mi; Lee, Jang-Sik

    2012-12-01

    A nonvolatile organic transistor memory device was developed using layer-by-layer assembly of 3-aminopropyltriethoxysilane (APTES) and solution-processed, reduced graphene oxide (rGO) as the charge trapping layer on flexible substrates. Reduction of graphene oxide and successful adsorption of the rGO on APTES-covered substrates were confirmed. The organic memory devices based on rGO exhibited reliable programmable memory operations, confirmed by program/erase operations, data retention, and endurance properties. These methods can potentially play a significant role in the fabrication of next-generation flexible nonvolatile memory devices based on graphene materials.

  11. Physical Mechanism and Fundamental Performance Limits on Graphene Non-Volatile Memory Technologies

    OpenAIRE

    Song, Emil Beom

    2012-01-01

    Non–volatile memory (NVM) constitutes a vital portion in electronics to retain information for both archiving and data processing. Limitations encountered in flash technology upon increasing density and reducing cost by scaling necessitates alternative memory structures beyond complementary–metal–oxide–semiconductor (CMOS). The single atomic two–dimensional profile and the superior physical properties of graphene allow advancements in a variety of memory metrics ...

  12. memCUDA: Map Device Memory to Host Memory on GPGPU Platform

    OpenAIRE

    Jin, Hai; Li, Bo; Zhang, Qin; Ao, Wenbing

    2010-01-01

    International audience; The Compute Unified Device Architecture (CUDA) programming environment from NVIDIA is a milestone towards making programming many-core GPUs more flexible to programmers. However, there are still many challenges for programmers when using CUDA. One is how to deal with GPU device memory, and data transfer between host memory and GPU device memory explicitly. In this study, source-to-source compiling and runtime library technologies are used to implement an experimental p...

  13. Radiation Damage in Electronic Memory Devices

    OpenAIRE

    Irfan Fetahović; Milić Pejović; Miloš Vujisić

    2013-01-01

    This paper investigates the behavior of semiconductor memories exposed to radiation in order to establish their applicability in a radiation environment. The experimental procedure has been used to test radiation hardness of commercial semiconductor memories. Different types of memory chips have been exposed to indirect ionizing radiation by changing radiation dose intensity. The effect of direct ionizing radiation on semiconductor memory behavior has been analyzed by using Monte Carlo simula...

  14. Bipolar resistive switching based on bis(8-hydroxyquinoline)cadmium complex: Mechanism and non-volatile memory application

    Institute of Scientific and Technical Information of China (English)

    Wang Ying; Yang Ting; Xie Ji-Peng; Lü Wen-Li; Fan Guo-Ying; Liu Su

    2013-01-01

    Stable and persistent bipolar resistive switching was observed in an organic diode with the structure of indium-tin oxide (ITO)/bis(8-hydroxyquinoline) cadmium (Cdq2)/Al.Aggregate formation and electric field driven trapping and detrapping of charge carriers in the aggregate states that lie in the energy gap of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the organic molecule were proposed as the mechanism of the observed bipolar resistive switching,and this was solidly supported by the results of AFM investigations.Repeatedly set,read,and reset measurements demonstrated that the device is potentially applicable in non-volatile memories.

  15. High-Speed Non-Volatile Optical Memory: Achievements and Challenges

    Directory of Open Access Journals (Sweden)

    Vadym Zayets

    2017-01-01

    Full Text Available We have proposed, fabricated, and studied a new design of a high-speed optical non-volatile memory. The recoding mechanism of the proposed memory utilizes a magnetization reversal of a nanomagnet by a spin-polarized photocurrent. It was shown experimentally that the operational speed of this memory may be extremely fast above 1 TBit/s. The challenges to realize both a high-speed recording and a high-speed reading are discussed. The memory is compact, integratable, and compatible with present semiconductor technology. If realized, it will advance data processing and computing technology towards a faster operation speed.

  16. Memory-assisted measurement-device-independent quantum key distribution

    Science.gov (United States)

    Panayi, Christiana; Razavi, Mohsen; Ma, Xiongfeng; Lütkenhaus, Norbert

    2014-04-01

    A protocol with the potential of beating the existing distance records for conventional quantum key distribution (QKD) systems is proposed. It borrows ideas from quantum repeaters by using memories in the middle of the link, and that of measurement-device-independent QKD, which only requires optical source equipment at the user's end. For certain memories with short access times, our scheme allows a higher repetition rate than that of quantum repeaters with single-mode memories, thereby requiring lower coherence times. By accounting for various sources of nonideality, such as memory decoherence, dark counts, misalignment errors, and background noise, as well as timing issues with memories, we develop a mathematical framework within which we can compare QKD systems with and without memories. In particular, we show that with the state-of-the-art technology for quantum memories, it is potentially possible to devise memory-assisted QKD systems that, at certain distances of practical interest, outperform current QKD implementations.

  17. Testing for long memory in volatility in the Indian Forex market

    Directory of Open Access Journals (Sweden)

    Kumar Anoop S.

    2014-01-01

    Full Text Available This article attempts to verify the presence of long memory in volatility in the Indian foreign exchange market using daily bilateral returns of the Indian Rupee against the US dollar from 17/02/1994 to 08/11/2013. In the first part of the analysis the presence of long-term dependence is confirmed in the return series as well as in two measures of unconditional volatility (absolute returns and squared returns by employing three measures of long memory. Next, the presence of long memory in conditional volatility is tested using ARMA-FIGARCH and ARMA-FIAPARCH models under various distributional assumptions. The results confirm the presence of long memory in conditional variance for two models. In the last part, the presence of long memory in conditional mean and conditional variance is verified using ARFIMA-FIGARCH and ARFIMA-FIAPARCH models. It is also found that long-memory models fare well compared to short-memory models in sample forecast performance.

  18. Research on the relationship between the multifractality and long memory of realized volatility in the SSECI

    Science.gov (United States)

    Jia, Zhanliang; Cui, Meilan; Li, Handong

    2012-02-01

    We examine the multifractal properties of the realized volatility (RV) and realized bipower variation (RBV) series in the Shanghai Stock Exchange Composite Index (SSECI) by using the multifractal detrended fluctuation analysis (MF-DFA) method. We find that there exist distinct multifractal characteristics in the volatility series. The contributions of two different types of source of multifractality, namely, fat-tailed probability distributions and nonlinear temporal correlations, are studied. By using the unit root test, we also find the strength of the multifractality of the volatility time series is insensitive to the sampling frequency but that the long memory of these series is sensitive.

  19. Non-volatile main memory management methods based on a file system.

    Science.gov (United States)

    Oikawa, Shuichi

    2014-01-01

    There are upcoming non-volatile (NV) memory technologies that provide byte addressability and high performance. PCM, MRAM, and STT-RAM are such examples. Such NV memory can be used as storage because of its data persistency without power supply while it can be used as main memory because of its high performance that matches up with DRAM. There are a number of researches that investigated its uses for main memory and storage. They were, however, conducted independently. This paper presents the methods that enables the integration of the main memory and file system management for NV memory. Such integration makes NV memory simultaneously utilized as both main memory and storage. The presented methods use a file system as their basis for the NV memory management. We implemented the proposed methods in the Linux kernel, and performed the evaluation on the QEMU system emulator. The evaluation results show that 1) the proposed methods can perform comparably to the existing DRAM memory allocator and significantly better than the page swapping, 2) their performance is affected by the internal data structures of a file system, and 3) the data structures appropriate for traditional hard disk drives do not always work effectively for byte addressable NV memory. We also performed the evaluation of the effects caused by the longer access latency of NV memory by cycle-accurate full-system simulation. The results show that the effect on page allocation cost is limited if the increase of latency is moderate.

  20. Radiation Damage in Electronic Memory Devices

    Directory of Open Access Journals (Sweden)

    Irfan Fetahović

    2013-01-01

    Full Text Available This paper investigates the behavior of semiconductor memories exposed to radiation in order to establish their applicability in a radiation environment. The experimental procedure has been used to test radiation hardness of commercial semiconductor memories. Different types of memory chips have been exposed to indirect ionizing radiation by changing radiation dose intensity. The effect of direct ionizing radiation on semiconductor memory behavior has been analyzed by using Monte Carlo simulation method. Obtained results show that gamma radiation causes decrease in threshold voltage, being proportional to the absorbed dose of radiation. Monte Carlo simulations of radiation interaction with material proved to be significant and can be a good estimation tool in probing semiconductor memory behavior in radiation environment.

  1. Self-assembled three-dimensional non-volatile memories

    NARCIS (Netherlands)

    Abelmann, Leon; Tas, Niels; Berenschot, Erwin; Elwenspoek, Miko

    2010-01-01

    The continuous increase in capacity of non-volatile data storage systems will lead to bit densities of one bit per atom in 2020. Beyond this point, capacity can be increased by moving into the third dimension. We propose to use self-assembly of nanosized elements, either as a loosely organised assoc

  2. Nonvolatile WORM memory devices based on polymethacrylate with azoanthraquinone group

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel polymethacrylate containing azoanthraquinone chromophore in the side chain(PMAzoaq6) was synthesized and characterized.An electronic memory device having the indium-tin oxide(ITO)/PMAzoaq6/Al sandwich structure was fabricated and its electrical bistability was investigated.The as-fabricated device was initially found to be at the OFF state and the switching threshold voltage was 1.5 V.After undergoing the OFF-to-ON transition,the device maintains the high conducting state(ON state) even after turning off the electrical power and applying a reverse bias.The device exhibits a write-once-read-many-times(WORM) memory effect with a high ON/OFF current ratio of up to 105 and a long retention time in both ON and OFF states,which demonstrated that the synthetic azoanthraquinone-containing polymer possesses a high potential to become polymeric memory devices.

  3. Transparent and flexible write-once-read-many (WORM) memory device based on egg albumen

    Science.gov (United States)

    Qu, Bo; Lin, Qianru; Wan, Tao; Du, Haiwei; Chen, Nan; Lin, Xi; Chu, Dewei

    2017-08-01

    Egg albumen, as an important protein resource in nature, is an interesting dielectric material exhibiting many fascinating properties for the development of environmentally friendly electronic devices. Taking advantage of their extraordinary transparency and flexibility, this paper presents an innovative preparation approach for albumen thin film based write-once-read-many-times (WORM) memory devices in a simple, cost-effective manner. The fabricated device shows superior data retention properties including non-volatile character (over 105 s) and promising great read durability (106 times). Furthermore, our results suggested that the electric-field-induced trap-controlled space charge limited current (SCLC) conduction is responsible for the observed resistance switching effect. The present study may likely reveal another pathway towards complete see-through electrical devices.

  4. Radiation Tolerant, High Capacity Non-Volatile Memory Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The need for reliable, high capacity, radiation tolerant nonvolatile memory exists in many Human space flight applications. Most projects rely on COTS hardware for a...

  5. Reconfigurable Electronics and Non-Volatile Memory Research

    Science.gov (United States)

    2015-11-10

    manufacture, use, or sell any patented invention that may relate to them. This report is the result of contracted fundamental research deemed...Systems was the first to offer a phase change memory array for sale in the mid 2000’s. Later, engineering samples of phase-change memory arrays from...files by the test system for storage b) Analysis is accomplished using custom Matlab scripting c) Reports are auto-generated in MS Powerpoint 2

  6. A power-efficient and non-volatile programmable logic array based on phase change memory

    Science.gov (United States)

    Du, Yuan; Ye, Yong; Kang, Yong; Xia, Yangyang; Song, Zhitang; Chen, Bomy

    2016-10-01

    Recently, numerous efforts have been made on NVM-based Field Programmable Gate Arrays (FPGAs) because the emerging non-volatile memory (NVM) technologies have the advantages of lower leakage power and higher density than Static Random Access Memory (SRAM) technology. However, the cost and the scale of FPGAs are so high and large that they can't be applied in the consumer electronics field and Internet of Things (IoT). Due to the small scale and low cost, Programmable Logic Array (PLA) is an ideal option for these fields. However, up to now there are few researches on non-volatile PLA based on emerging NVMs. In this paper, a power-efficient non-volatile PLA based on Phase Change Memory (PCM) is proposed. The proposed non-volatile PLA architecture has been evaluated using the 40 nm Complementary Metal Oxide Semiconductor (CMOS) technology, and the simulation results show the correct functionality of the PLA. After the PLA reads the configuration bits from the non-volatile programmable elements (PEs), the power of the programmable elements can be OFF. Therefore, the standby power of the programmable elements is much smaller than that of the commonly SRAM-based PLAs. The simulation results also show that the total power of nvPLA is reduced by about 53.6% when the supply power of Programmable Element is OFF.

  7. Novel spintronics devices for memory and logic: prospects and challenges for room temperature all spin computing

    Science.gov (United States)

    Wang, Jian-Ping

    An energy efficient memory and logic device for the post-CMOS era has been the goal of a variety of research fields. The limits of scaling, which we expect to reach by the year 2025, demand that future advances in computational power will not be realized from ever-shrinking device sizes, but rather by innovative designs and new materials and physics. Magnetoresistive based devices have been a promising candidate for future integrated magnetic computation because of its unique non-volatility and functionalities. The application of perpendicular magnetic anisotropy for potential STT-RAM application was demonstrated and later has been intensively investigated by both academia and industry groups, but there is no clear path way how scaling will eventually work for both memory and logic applications. One of main reasons is that there is no demonstrated material stack candidate that could lead to a scaling scheme down to sub 10 nm. Another challenge for the usage of magnetoresistive based devices for logic application is its available switching speed and writing energy. Although a good progress has been made to demonstrate the fast switching of a thermally stable magnetic tunnel junction (MTJ) down to 165 ps, it is still several times slower than its CMOS counterpart. In this talk, I will review the recent progress by my research group and my C-SPIN colleagues, then discuss the opportunities, challenges and some potential path ways for magnetoresitive based devices for memory and logic applications and their integration for room temperature all spin computing system.

  8. Review of Emerging New Solid-State Non-Volatile Memories

    Science.gov (United States)

    Fujisaki, Yoshihisa

    2013-04-01

    The integration limit of flash memories is approaching, and many new types of memory to replace conventional flash memories have been proposed. Unlike flash memories, new nonvolatile memories do not require storage of electric charges. The possibility of phase-change random-access memories (PCRAMs) or resistive-change RAMs (ReRAMs) replacing ultrahigh-density NAND flash memories has been investigated; however, many issues remain to be overcome, making the replacement difficult. Nonetheless, ferroelectric RAMs (FeRAMs) and magnetoresistive RAMs (MRAMs) are gradually penetrating into fields where the shortcomings of flash memories, such as high operating voltage, slow rewriting speed, and limited number of rewrites, make their use inconvenient. For instance, FeRAMs are widely used in ICs that require low power consumption such as smart cards and wireless tags. MRAMs are used in many kinds of controllers in industrial equipment that require high speed and unlimited rewrite operations. For successful application of new non-volatile semiconductor memories, such memories must be practically utilized in new fields in which flash memories are not applicable, and their technologies must be further developed.

  9. Malware Memory Analysis of the Jynx2 Linux Rootkit (Part 1): Investigating a Publicly Available Linux Rootkit Using the Volatility Memory Analysis Framework

    Science.gov (United States)

    2014-10-01

    Malware memory analysis of the Jynx2 Linux rootkit (Part 1) Investigating a publicly available Linux rootkit using the Volatility memory...nationale, 2014 DRDC-RDDC-2014-R176 i Abstract …….. This report is the second in a series that will examine Linux Volatility-specific memory...reports, some of the techniques described therein are not applicable to Linux -based analyses including data carving and anti-virus scanning. Thus

  10. Structure of phase-separated ferroelectric/ semiconducting polymer blends for organic non-volatile memories

    NARCIS (Netherlands)

    Mcneill, C.R.; Asadi, K.; Watts, B.; Blom, P.W.M.; Leeuw, D.M. de

    2010-01-01

    The phase-separated structure of blends of the ferroelectric polymer P(VDF-TrFE) and the semiconducting polymer P3HT used in organic non-volatile memories is revealed with soft X-ray spectromicroscopy. These thin-film blends show a columnar morphology, with P3HT-rich columns enclosed in a continuous

  11. Coding with Side Information for Radiation-Tolerant Memory Devices

    Science.gov (United States)

    Hwang, E.; Jeon, S.; Negi, R.; Vijaya Kumar, B. V. K.; Cheng, M. K.

    2011-11-01

    Memory devices aboard spacecraft experience radiation-induced errors either in the form of temporary upsets (soft errors) or permanent defects (hard or stuck-at errors). Error-correcting codes (ECCs) are used to recover memory content from errors where defective cells are either regarded as erasures by the decoder or entire blocks containing defective cells are marked as unusable. In this article, alternative coding schemes are investigated for memory devices in space, where the encoder is provided with the locations of the defective cells, denoted by side information. This coding approach has the potential to improve the overall storage capacity of memory devices, since the information theoretic capacity of a channel where side information is only available at the encoder is the same as the capacity where side information is available at both the encoder and decoder. Spacecraft memory controllers typically scrub memory devices periodically for errors. Partial side information can be obtained during this scrubbing process by comparing the ECC decoder output with its input and thereby avoid the need for additional cell tests or storage overhead. In between scrubbings, the encoder can use this partial side information to account for permanent defects to improve reliability or to increase the storage capacity of onboard memory devices. In order to achieve performance gains for practical memory systems, several coding schemes that adaptively incorporate the codeword with the known side information are proposed in this article. The proposed coding schemes are evaluated by numerical simulations on a memory channel model characterized by soft and hard errors. Simulation results show that while coding with complete side information at the encoder offers the most performance gain compared to when coding without side information is used, coding with partial side information can close the gap between the optimal and current approach without incurring much additional overhead

  12. First principles modeling of magnetic random access memory devices (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Butler, W.H.; Zhang, X.; Schulthess, T.C.; Nicholson, D.M.; Oparin, A.B. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); MacLaren, J.M. [Department of Physics, Tulane University, New Orleans, Louisiana 70018 (United States)

    1999-04-01

    Giant magnetoresistance (GMR) and spin-dependent tunneling may be used to make magnetic random access memory devices. We have applied first-principles based electronic structure techniques to understand these effects and in the case of GMR to model the transport properties of the devices. {copyright} {ital 1999 American Institute of Physics.}

  13. Scaling and memory in volatility return intervals in financial markets

    Science.gov (United States)

    Yamasaki, Kazuko; Muchnik, Lev; Havlin, Shlomo; Bunde, Armin; Stanley, H. Eugene

    2005-06-01

    For both stock and currency markets, we study the return intervals τ between the daily volatilities of the price changes that are above a certain threshold q. We find that the distribution function Pq(τ) scales with the mean return interval [Formula] as [Formula]. The scaling function f(x) is similar in form for all seven stocks and for all seven currency databases analyzed, and f(x) is consistent with a power-law form, f(x) ˜ x-γ with γ ≈ 2. We also quantify how the conditional distribution Pq(τ|τ0) depends on the previous return interval τ0 and find that small (or large) return intervals are more likely to be followed by small (or large) return intervals. This “clustering” of the volatility return intervals is a previously unrecognized phenomenon that we relate to the long-term correlations known to be present in the volatility. Author contributions: S.H. and H.E.S. designed research; K.Y., L.M., S.H., and H.E.S. performed research; A.B. contributed new reagents/analytic tools; A.B. analyzed data; and S.H. wrote the paper.Abbreviations: pdf, probability density function; S&P 500, Standard and Poor's 500 Index; USD, U.S. dollar; JPY, Japanese yen; SEK, Swedish krona.

  14. Four-state non-volatile memory in a multiferroic spin filter tunnel junction

    Science.gov (United States)

    Ruan, Jieji; Li, Chen; Yuan, Zhoushen; Wang, Peng; Li, Aidong; Wu, Di

    2016-12-01

    We report a spin filter type multiferroic tunnel junction with a ferromagnetic/ferroelectric bilayer barrier. Memory functions of a spin filter magnetic tunnel junction and a ferroelectric tunnel junction are combined in this single device, producing four non-volatile resistive states that can be read out in a non-destructive manner. This concept is demonstrated in a LaNiO3/Pr0.8Ca0.2MnO3/BaTiO3/La0.7Sr0.3MnO3 all-oxide tunnel junction. The ferromagnetic insulator Pr0.8Ca0.2MnO3 serves as the spin filter and the ferromagnetic metal La0.7Sr0.3MnO3 is the spin analyzer. The ferroelectric polarization reversal in the BaTiO3 barrier switches the tunneling barrier height to produce a tunneling electroresistance. The ferroelectric switching also modulates the spin polarization and the spin filtering efficiency in Pr0.8Ca0.2MnO3.

  15. Improving reliability of non-volatile memory technologies through circuit level techniques and error control coding

    Science.gov (United States)

    Yang, Chengen; Emre, Yunus; Cao, Yu; Chakrabarti, Chaitali

    2012-12-01

    Non-volatile resistive memories, such as phase-change RAM (PRAM) and spin transfer torque RAM (STT-RAM), have emerged as promising candidates because of their fast read access, high storage density, and very low standby power. Unfortunately, in scaled technologies, high storage density comes at a price of lower reliability. In this article, we first study in detail the causes of errors for PRAM and STT-RAM. We see that while for multi-level cell (MLC) PRAM, the errors are due to resistance drift, in STT-RAM they are due to process variations and variations in the device geometry. We develop error models to capture these effects and propose techniques based on tuning of circuit level parameters to mitigate some of these errors. Unfortunately for reliable memory operation, only circuit-level techniques are not sufficient and so we propose error control coding (ECC) techniques that can be used on top of circuit-level techniques. We show that for STT-RAM, a combination of voltage boosting and write pulse width adjustment at the circuit-level followed by a BCH-based ECC scheme can reduce the block failure rate (BFR) to 10-8. For MLC-PRAM, a combination of threshold resistance tuning and BCH-based product code ECC scheme can achieve the same target BFR of 10-8. The product code scheme is flexible; it allows migration to a stronger code to guarantee the same target BFR when the raw bit error rate increases with increase in the number of programming cycles.

  16. Organic memory device with polyaniline nanoparticles embedded as charging elements

    Science.gov (United States)

    Kim, Yo-Han; Kim, Minkeun; Oh, Sewook; Jung, Hunsang; Kim, Yejin; Yoon, Tae-Sik; Kim, Yong-Sang; Ho Lee, Hyun

    2012-04-01

    Polyaniline nanoparticles (PANI NPs) were synthesized and fabricated as charging elements for organic memory devices. The PANI NPs charging layer was self-assembled by epoxy-amine bonds between 3-glycidylpropyl trimethoxysilane functionalized dielectrics and PANI NPs. A memory window of 5.8 V (ΔVFB) represented by capacitance-voltage hysteresis was obtained for metal-pentacene-insulator-silicon capacitor. In addition, program/erase operations controlled by gate bias (-/+90 V) were demonstrated in the PANI NPs embedded pentacene thin film transistor device with polyvinylalcohol dielectric on flexible polyimide substrate. These results can be extended to development of fully organic-based electronic device.

  17. Reconfigurable Electronics and Non-Volatile Memory Research

    Science.gov (United States)

    2011-10-14

    measurements. Probe tips were either Micromanipulator W size 7B or American Probe and Technologies 73CT- APTA probe tips. The tested devices were...Technologies 73CT- APTA probe tips. The tested devices were 250 nm in diameter as defined by the via etched through the nitride layer to the bottom

  18. Effect of electrode material on characteristics of non-volatile resistive memory consisting of Ag2S nanoparticles

    Science.gov (United States)

    Jang, Jaewon

    2016-07-01

    In this study, Ag2S nanoparticles are synthesized and used as the active material for two-terminal resistance switching memory devices. Sintered Ag2S films are successfully crystallized on plastic substrates with synthesized Ag2S nanoparticles, after a relatively low-temperature sintering process (200 °C). After the sintering process, the crystallite size is increased from 6.8 nm to 80.3 nm. The high ratio of surface atoms to inner atoms of nanoparticles reduces the melting point temperature, deciding the sintering process temperature. In order to investigate the resistance switching characteristics, metal/Ag2S/metal structures are fabricated and tested. The effect of the electrode material on the non-volatile resistive memory characteristics is studied. The bottom electrochemically inert materials, such as Au and Pt, were critical for maintaining stable memory characteristics. By using Au and Pt inert bottom electrodes, we are able to significantly improve the memory endurance and retention to more than 103 cycles and 104 sec, respectively.

  19. Scalable printed electronics: an organic decoder addressing ferroelectric non-volatile memory

    National Research Council Canada - National Science Library

    Ng, Tse Nga; Schwartz, David E; Lavery, Leah L; Whiting, Gregory L; Russo, Beverly; Krusor, Brent; Veres, Janos; Bröms, Per; Herlogsson, Lars; Alam, Naveed; Hagel, Olle; Nilsson, Jakob; Karlsson, Christer

    2012-01-01

    .... The decoder-memory array is patterned by inkjet and gravure printing on flexible plastics. Simulation models for the organic transistors are developed, enabling circuit designs tolerant of the variations in printed devices...

  20. Memory devices based on organic electric bistable materials

    Institute of Scientific and Technical Information of China (English)

    CHEN Qi; BAI Hua; SHI GaoQuan

    2007-01-01

    Organic/metallic composites have demonstrated electrical bistability, as well as memory effects. These advanced materials have shown potential applications in digital information storage because of their good stability, flexibility and fast response speed. The electric bistability phenomenon can be explained by electric field-induced electron transfer/storage. This article reviews the recent progress of memory devices based on organic/metallic and polymeric composites with electric bistability.

  1. Pattern recognition with magnonic holographic memory device

    Energy Technology Data Exchange (ETDEWEB)

    Kozhevnikov, A.; Dudko, G.; Filimonov, Y. [Kotel' nikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Saratov Branch, Saratov 410019 (Russian Federation); Gertz, F.; Khitun, A. [Electrical Engineering Department, University of California - Riverside, Riverside, California 92521 (United States)

    2015-04-06

    In this work, we present experimental data demonstrating the possibility of using magnonic holographic devices for pattern recognition. The prototype eight-terminal device consists of a magnetic matrix with micro-antennas placed on the periphery of the matrix to excite and detect spin waves. The principle of operation is based on the effect of spin wave interference, which is similar to the operation of optical holographic devices. Input information is encoded in the phases of the spin waves generated on the edges of the magnonic matrix, while the output corresponds to the amplitude of the inductive voltage produced by the interfering spin waves on the other side of the matrix. The level of the output voltage depends on the combination of the input phases as well as on the internal structure of the magnonic matrix. Experimental data collected for several magnonic matrixes show the unique output signatures in which maxima and minima correspond to specific input phase patterns. Potentially, magnonic holographic devices may provide a higher storage density compare to optical counterparts due to a shorter wavelength and compatibility with conventional electronic devices. The challenges and shortcoming of the magnonic holographic devices are also discussed.

  2. Design of a Multi-Level/Analog Ferroelectric Memory Device

    Science.gov (United States)

    MacLeod, Todd C.; Phillips, Thomas A.; Ho, Fat D.

    2006-01-01

    Increasing the memory density and utilizing the dove1 characteristics of ferroelectric devices is important in making ferroelectric memory devices more desirable to the consumer. This paper describes a design that allows multiple levels to be stored in a ferroelectric based memory cell. It can be used to store multiple bits or analog values in a high speed nonvolatile memory. The design utilizes the hysteresis characteristic of ferroelectric transistors to store an analog value in the memory cell. The design also compensates for the decay of the polarization of the ferroelectric material over time. This is done by utilizing a pair of ferroelectric transistors to store the data. One transistor is used as a reference to determine the amount of decay that has occurred since the pair was programmed. The second transistor stores the analog value as a polarization value between zero and saturated. The design allows digital data to be stored as multiple bits in each memory cell. The number of bits per cell that can be stored will vary with the decay rate of the ferroelectric transistors and the repeatability of polarization between transistors. It is predicted that each memory cell may be able to store 8 bits or more. The design is based on data taken from actual ferroelectric transistors. Although the circuit has not been fabricated, a prototype circuit is now under construction. The design of this circuit is different than multi-level FLASH or silicon transistor circuits. The differences between these types of circuits are described in this paper. This memory design will be useful because it allows higher memory density, compensates for the environmental and ferroelectric aging processes, allows analog values to be directly stored in memory, compensates for the thermal and radiation environments associated with space operations, and relies only on existing technologies.

  3. Design of a Multi-Level/Analog Ferroelectric Memory Device

    Science.gov (United States)

    MacLeod, Todd C.; Phillips, Thomas A.; Ho, Fat D.

    2006-01-01

    Increasing the memory density and utilizing the dove1 characteristics of ferroelectric devices is important in making ferroelectric memory devices more desirable to the consumer. This paper describes a design that allows multiple levels to be stored in a ferroelectric based memory cell. It can be used to store multiple bits or analog values in a high speed nonvolatile memory. The design utilizes the hysteresis characteristic of ferroelectric transistors to store an analog value in the memory cell. The design also compensates for the decay of the polarization of the ferroelectric material over time. This is done by utilizing a pair of ferroelectric transistors to store the data. One transistor is used as a reference to determine the amount of decay that has occurred since the pair was programmed. The second transistor stores the analog value as a polarization value between zero and saturated. The design allows digital data to be stored as multiple bits in each memory cell. The number of bits per cell that can be stored will vary with the decay rate of the ferroelectric transistors and the repeatability of polarization between transistors. It is predicted that each memory cell may be able to store 8 bits or more. The design is based on data taken from actual ferroelectric transistors. Although the circuit has not been fabricated, a prototype circuit is now under construction. The design of this circuit is different than multi-level FLASH or silicon transistor circuits. The differences between these types of circuits are described in this paper. This memory design will be useful because it allows higher memory density, compensates for the environmental and ferroelectric aging processes, allows analog values to be directly stored in memory, compensates for the thermal and radiation environments associated with space operations, and relies only on existing technologies.

  4. Terrestrial neutron-induced soft errors in advanced memory devices

    CERN Document Server

    Nakamura, Takashi; Ibe, Eishi; Yahagi, Yasuo; Kameyama, Hideaki

    2008-01-01

    Terrestrial neutron-induced soft errors in semiconductor memory devices are currently a major concern in reliability issues. Understanding the mechanism and quantifying soft-error rates are primarily crucial for the design and quality assurance of semiconductor memory devices. This book covers the relevant up-to-date topics in terrestrial neutron-induced soft errors, and aims to provide succinct knowledge on neutron-induced soft errors to the readers by presenting several valuable and unique features. Sample Chapter(s). Chapter 1: Introduction (238 KB). Table A.30 mentioned in Appendix A.6 on

  5. Comparing Predictive Accuracy under Long Memory - With an Application to Volatility Forecasting

    DEFF Research Database (Denmark)

    Kruse, Robinson; Leschinski, Christian; Will, Michael

    This paper extends the popular Diebold-Mariano test to situations when the forecast error loss differential exhibits long memory. It is shown that this situation can arise frequently, since long memory can be transmitted from forecasts and the forecast objective to forecast error loss differentials....... The nature of this transmission mainly depends on the (un)biasedness of the forecasts and whether the involved series share common long memory. Further results show that the conventional Diebold-Mariano test is invalidated under these circumstances. Robust statistics based on a memory and autocorrelation...... extensions of the heterogeneous autoregressive model. While we find that forecasts improve significantly if jumps in the log-price process are considered separately from continuous components, improvements achieved by the inclusion of implied volatility turn out to be insignificant in most situations....

  6. In search of the next memory inside the circuitry from the oldest to the emerging non-volatile memories

    CERN Document Server

    Campardo, Giovanni

    2017-01-01

    This book provides students and practicing chip designers with an easy-to-follow yet thorough, introductory treatment of the most promising emerging memories under development in the industry. Focusing on the chip designer rather than the end user, this book offers expanded, up-to-date coverage of emerging memories circuit design. After an introduction on the old solid-state memories and the fundamental limitations soon to be encountered, the working principle and main technology issues of each of the considered technologies (PCRAM, MRAM, FeRAM, ReRAM) are reviewed and a range of topics related to design is explored: the array organization, sensing and writing circuitry, programming algorithms and error correction techniques are reviewed comparing the approach followed and the constraints for each of the technologies considered. Finally the issue of radiation effects on memory devices has been briefly treated. Additionally some considerations are entertained about how emerging memories can find a place in the...

  7. Ultrathin flexible memory devices based on organic ferroelectric transistors

    Science.gov (United States)

    Sugano, Ryo; Hirai, Yoshinori; Tashiro, Tomoya; Sekine, Tomohito; Fukuda, Kenjiro; Kumaki, Daisuke; Domingues dos Santos, Fabrice; Miyabo, Atsushi; Tokito, Shizuo

    2016-10-01

    Here, we demonstrate ultrathin, flexible nonvolatile memory devices with excellent durability under compressive strain. Ferroelectric-gate field-effect transistors (FeFETs) employing organic semiconductor and polymer ferroelectric layers are fabricated on a 1-µm-thick plastic film substrate. The FeFETs are characterized by measuring their transfer characteristics, programming time, and data retention time. The data retention time is almost unchanged even when a 50% compressive strain is applied to the devices. To clarify the origin of the excellent durability of the devices against compressive strain, an intermediate plane is calculated. From the calculation result, the intermediate plane is placed close to the channel region of the FeFETs. The high flexibility of the ferroelectric polymer and ultrathin device structure contributes to achieving a bending radius of 0.8 µm without the degradation of memory characteristics.

  8. Solution-processed Al-chelated gelatin for highly transparent non-volatile memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yu-Chi; Wang, Yeong-Her, E-mail: yhw@ee.ncku.edu.tw [Institute of Microelectronics and Department of Electrical Engineering, Advanced Optoelectronic Technology Center, National Cheng-Kung University, Tainan 701 Taiwan (China)

    2015-03-23

    Using the biomaterial of Al-chelated gelatin (ACG) prepared by sol-gel method in the ITO/ACG/ITO structure, a highly transparent resistive random access memory (RRAM) was obtained. The transmittance of the fabricated device is approximately 83% at 550 nm while that of Al/gelatin/ITO is opaque. As to the ITO/gelatin/ITO RRAM, no resistive switching behavior can be seen. The ITO/ACG/ITO RRAM shows high ON/OFF current ratio (>10{sup 5}), low operation voltage, good uniformity, and retention characteristics at room temperature and 85 °C. The mechanism of the ACG-based memory devices is presented. The enhancement of these electrical properties can be attributed to the chelate effect of Al ions with gelatin. Results show that transparent ACG-based memory devices possess the potential for next-generation resistive memories and bio-electronic applications.

  9. Inverse heat conduction problem in a phase change memory device

    Science.gov (United States)

    Battaglia, Jean-Luc; De, Indrayush; Sousa, Véronique

    2017-01-01

    An invers heat conduction problem is solved considering the thermal investigation of a phase change memory device using the scanning thermal microscopy. The heat transfer model rests on system identification for the probe thermal impedance and on a finite element method for the device thermal impedance. Unknown parameters in the model are then identified using a nonlinear least square algorithm that minimizes the quadratic gap between the measured probe temperature and the simulated one.

  10. Exploring Spin-transfer-torque devices and memristors for logic and memory applications

    Science.gov (United States)

    Pajouhi, Zoha

    As scaling CMOS devices is approaching its physical limits, researchers have begun exploring newer devices and architectures to replace CMOS. Due to their non-volatility and high density, Spin Transfer Torque (STT) devices are among the most prominent candidates for logic and memory applications. In this research, we first considered a new logic style called All Spin Logic (ASL). Despite its advantages, ASL consumes a large amount of static power; thus, several optimizations can be performed to address this issue. We developed a systematic methodology to perform the optimizations to ensure stable operation of ASL. Second, we investigated reliable design of STT-MRAM bit-cells and addressed the conflicting read and write requirements, which results in overdesign of the bit-cells. Further, a Device/Circuit/Architecture co-design framework was developed to optimize the STT-MRAM devices by exploring the design space through jointly considering yield enhancement techniques at different levels of abstraction. Recent advancements in the development of memristive devices have opened new opportunities for hardware implementation of non-Boolean computing. To this end, the suitability of memristive devices for swarm intelligence algorithms has enabled researchers to solve a maze in hardware. In this research, we utilized swarm intelligence of memristive networks to perform image edge detection. First, we proposed a hardware-friendly algorithm for image edge detection based on ant colony. Next, we designed the image edge detection algorithm using memristive networks.

  11. The analysis of polarization characteristics on 40nm memory devices

    Science.gov (United States)

    Yoo, Minae; Park, Chanha; You, Taejun; Yang, Hyunjo; Min, Young-Hong; Park, Ki-Yeop; Yim, Donggyu; Park, Sungki

    2009-03-01

    Hyper NA system has been introduced to develop sub-60nm node memory devices. Especially memory industries including DRAM and NAND Flash business have driven much finer technology to improve productivity. Polarization at hyper NA has been well known as important optical technology to enhance imaging performance and also achieve very low k1 process. The source polarization on dense structure has been used as one of the major RET techniques. The process capabilities of various layers under specific illumination and polarization have been explored. In this study, polarization characteristic on 40nm memory device will be analyzed. Especially, TE (Transverse Electric) polarization and linear X-Y polarization on hyper NA ArF system will be compared and investigated. First, IPS (Intensity in Preferred State) value will be measured with PMM (Polarization Metrology Module) to confirm polarization characteristic of each machine before simulation. Next simulation will be done to estimate the CD variation impact of each polarization to different illumination. Third, various line and space pattern of DRAM and Flash device will be analyzed under different polarized condition to see the effect of polarization on CD of actual wafer. Finally, conclusion will be made for this experiment and future work will be discussed. In this paper, the behavior of 40nm node memory devices with two types of polarization is presented and the guidelines for polarization control is discussed based on the patterning performances.

  12. Automatic memory management policies for low power, memory limited, and delay intolerant devices

    Science.gov (United States)

    Jahid, Md. Abu

    Mobile devices such as smartphones and tablets are energy and memory limited, and implement graphical user interfaces that are intolerant of computational delays. Mobile device platforms supporting apps implemented in languages that require automatic memory management, such as the Dalvik (Java) virtual machine within Google's Android, have become dominant. It is essential that automatic memory management avoid causing unacceptable interface delays while responsibly managing energy and memory resource usage. Dalvik's automatic memory management policies for heap growth and garbage collection scheduling utilize heuristics tuned to minimize memory footprint. These policies result in only marginally acceptable response times and garbage collection signicantly contributes to apps' CPU time and therefore energy consumption. The primary contributions of this research include a characterization of Dalvik's "baseline" automatic memory management policy, the development of a new "adaptive" policy, and an investigation of the performance of this policy. The investigation indicates that this adaptive policy consumes less CPU time and improves interactive performance at the cost of increasing memory footprint size by an acceptable amount.

  13. Application of nanomaterials in two-terminal resistive-switching memory devices

    Directory of Open Access Journals (Sweden)

    Jianyong Ouyang

    2010-05-01

    Full Text Available Nanometer materials have been attracting strong attention due to their interesting structure and properties. Many important practical applications have been demonstrated for nanometer materials based on their unique properties. This article provides a review on the fabrication, electrical characterization, and memory application of two-terminal resistive-switching devices using nanomaterials as the active components, including metal and semiconductor nanoparticles (NPs, nanotubes, nanowires, and graphenes. There are mainly two types of device architectures for the two-terminal devices with NPs. One has a triple-layer structure with a metal film sandwiched between two organic semiconductor layers, and the other has a single polymer film blended with NPs. These devices can be electrically switched between two states with significant different resistances, i.e. the ‘ON’ and ‘OFF’ states. These render the devices important application as two-terminal non-volatile memory devices. The electrical behavior of these devices can be affected by the materials in the active layer and the electrodes. Though the mechanism for the electrical switches has been in argument, it is generally believed that the resistive switches are related to charge storage on the NPs. Resistive switches were also observed on crossbars formed by nanotubes, nanowires, and graphene ribbons. The resistive switches are due to nanoelectromechanical behavior of the materials. The Coulombic interaction of transient charges on the nanomaterials affects the configurable gap of the crossbars, which results into significant change in current through the crossbars. These nanoelectromechanical devices can be used as fast-response and high-density memory devices as well. Dr. Jianyong Ouyang received his bachelor degree from the Tsinghua University in Beijing, China, and MSc from the Institute of Chemistry, Chinese Academy of Science. He received his PhD from the Institute for Molecular

  14. New device for direct extraction of volatiles in solid samples using SPME.

    Science.gov (United States)

    Ruiz, J; Ventanas, J; Cava, R

    2001-11-01

    A new device that allows extraction of volatiles from solid materials by SPME, avoiding preparation of the sample, was designed and tested in two different food products. Volatiles from dry-cured ham and canned liver sausage were analyzed by headspace SPME (HS SPME) and by using a new device that protects the SPME fiber in the core of the solid material. Volatile profiles generated by using both methods of extraction were very similar in both products. Compounds that have been previously highlighted as quality markers, such as products from oxidative degradation of lipids, products from Strecker degradation of amino acids, or terpenes, were satisfactorily extracted by SPME coupled to the device for direct extraction. In addition, by using this method no laboratory contaminants were extracted, whereas some major laboratory solvents were presented in the chromatogram using the HS SPME method. However, coefficients of variation were higher when performing the direct sampling procedure. This new device appears to have potential as a simple method for extracting volatiles in solid materials while at the same time avoiding taking samples.

  15. Multilevel conductance switching of memory device through photoelectric effect.

    Science.gov (United States)

    Ye, Changqing; Peng, Qian; Li, Mingzhu; Luo, Jia; Tang, Zhengming; Pei, Jian; Chen, Jianming; Shuai, Zhigang; Jiang, Lei; Song, Yanlin

    2012-12-12

    A photoelectronic switch of a multilevel memory device has been achieved using a meta-conjugated donor-bridge-acceptor (DBA) molecule. Such a DBA optoelectronic molecule responds to both the optical and electrical stimuli. The device exhibits good electrical bistable switching behaviors under dark, with a large ON/OFF ratio more than 10(6). In cooperation with the UV light, photoelectronic ternary states are addressable in a bistable switching system. On the basis of the CV measurement, charge carriers transport modeling, quantum chemical calculation, and absorption spectra analysis, the mechanism of the DBA memory is suggested to be attributed to the substep charge transfer transition process. The capability of tailoring photoelectrical properties is a very promising strategy to explore the multilevel storage, and it will give a new opportunity for designing multifunctional devices.

  16. A Survey of Soft-Error Mitigation Techniques for Non-Volatile Memories

    Directory of Open Access Journals (Sweden)

    Sparsh Mittal

    2017-02-01

    Full Text Available Non-volatile memories (NVMs offer superior density and energy characteristics compared to the conventional memories; however, NVMs suffer from severe reliability issues that can easily eclipse their energy efficiency advantages. In this paper, we survey architectural techniques for improving the soft-error reliability of NVMs, specifically PCM (phase change memory and STT-RAM (spin transfer torque RAM. We focus on soft-errors, such as resistance drift and write disturbance, in PCM and read disturbance and write failures in STT-RAM. By classifying the research works based on key parameters, we highlight their similarities and distinctions. We hope that this survey will underline the crucial importance of addressing NVM reliability for ensuring their system integration and will be useful for researchers, computer architects and processor designers.

  17. Improving Memory Characteristics of Hydrogenated Nanocrystalline Silicon Germanium Nonvolatile Memory Devices by Controlling Germanium Contents.

    Science.gov (United States)

    Kim, Jiwoong; Jang, Kyungsoo; Phu, Nguyen Thi Cam; Trinh, Thanh Thuy; Raja, Jayapal; Kim, Taeyong; Cho, Jaehyun; Kim, Sangho; Park, Jinjoo; Jung, Junhee; Lee, Youn-Jung; Yi, Junsin

    2016-05-01

    Nonvolatile memory (NVM) with silicon dioxide/silicon nitride/silicon oxynitride (ONO(n)) charge trap structure is a promising flash memory technology duo that will fulfill process compatibility for system-on-panel displays, down-scaling cell size and low operation voltage. In this research, charge trap flash devices were fabricated with ONO(n) stack gate insulators and an active layer using hydrogenated nanocrystalline silicon germanium (nc-SiGe:H) films at a low temperature. In this study, the effect of the interface trap density on the performance of devices, including memory window and retention, was investigated. The electrical characteristics of NVM devices were studied controlling Ge content from 0% to 28% in the nc-SiGe:H channel layer. The optimal Ge content in the channel layer was found to be around 16%. For nc-SiGe:H NVM with 16% Ge content, the memory window was 3.13 V and the retention data exceeded 77% after 10 years under the programming condition of 15 V for 1 msec. This showed that the memory window increased by 42% and the retention increased by 12% compared to the nc-Si:H NVM that does not contain Ge. However, when the Ge content was more than 16%, the memory window and retention property decreased. Finally, this research showed that the Ge content has an effect on the interface trap density and this enabled us to determine the optimal Ge content.

  18. A Novel Wireless Wearable Volatile Organic Compound (VOC Monitoring Device with Disposable Sensors

    Directory of Open Access Journals (Sweden)

    Yue Deng

    2016-12-01

    Full Text Available A novel portable wireless volatile organic compound (VOC monitoring device with disposable sensors is presented. The device is miniaturized, light, easy-to-use, and cost-effective. Different field tests have been carried out to identify the operational, analytical, and functional performance of the device and its sensors. The device was compared to a commercial photo-ionization detector, gas chromatography-mass spectrometry, and carbon monoxide detector. In addition, environmental operational conditions, such as barometric change, temperature change and wind conditions were also tested to evaluate the device performance. The multiple comparisons and tests indicate that the proposed VOC device is adequate to characterize personal exposure in many real-world scenarios and is applicable for personal daily use.

  19. Fully transparent, non-volatile bipolar resistive memory based on flexible copolyimide films

    Science.gov (United States)

    Yu, Hwan-Chul; Kim, Moon Young; Hong, Minki; Nam, Kiyong; Choi, Ju-Young; Lee, Kwang-Hun; Baeck, Kyoung Koo; Kim, Kyoung-Kook; Cho, Soohaeng; Chung, Chan-Moon

    2017-01-01

    Partially aliphatic homopolyimides and copolyimides were prepared from rel-(1'R,3S,5'S)-spiro[furan-3(2H),6'-[3]oxabicyclo[3.2.1]octane]-2,2',4',5(4H)-tetrone (DAn), 2,6-diaminoanthracene (AnDA), and 4,4'-oxydianiline (ODA) by varying the molar ratio of AnDA and ODA. We utilized these polyimide films as the resistive switching layer in transparent memory devices. While WORM memory behavior was obtained with the PI-A100-O0-based device (molar feed ratio of DAn : AnDA : ODA = 1 : 1 : 0), the PI-A70-O30-based device (molar feed ratio of DAn : AnDA : ODA = 1 : 0.7 : 0.3) exhibited bipolar resistive switching behavior with stable retention for 104 s. This result implies that the memory properties can be controlled by changing the polyimide composition. The two devices prepared from PI-A100-O0 and PI-A70-O30 showed over 90% transmittance in the visible wavelength range from 400 to 800 nm. The behavior of the memory devices is considered to be governed by trap-controlled, space-charge limited conduction (SCLC) and local filament formation. [Figure not available: see fulltext.

  20. Computerised memory: digital devices and writing the self

    Directory of Open Access Journals (Sweden)

    Oriane DESEILLIGNY

    2012-01-01

    Full Text Available Based on the analysis of the diary’s textual form, this paper examines the way the latter is quoted and transformed with digital devices. Reviewing handwritten or digitised diaries, weblogs and Facebook, we observe the transformations of this textual form as well as the values invested by its users, devices and media.We compare the link with memory in each medium and the way it can – or cannot – be analysed in terms of writing the self, according to Foucault.

  1. Gold volatile species atomization and preconcentration in quartz devices for atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Arslan, Yasin [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Mehmet Akif Ersoy University, Faculty of Arts & Sciences, Chemistry Department, 15030 Burdur (Turkey); Musil, Stanislav; Matoušek, Tomáš; Kratzer, Jan [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Dědina, Jiří, E-mail: dedina@biomed.cas.cz [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic)

    2015-01-01

    The on-line atomization of gold volatile species was studied and the results were compared with thermodynamic calculations in several quartz atomizers, namely: diffusion flame, flame-in-gas-shield, flame-in-plain-tube, externally heated T-tube and externally heated flame-in-T-tube. Atomization mechanism in the explored devices is proposed, where volatile species are converted to thermodynamically stable AuH at elevated temperature over 500 °C and then atomized by an interaction with a cloud of hydrogen radicals. Because of its inherent simplicity and robustness, diffusion flame was employed as a reference atomizer. It yielded atomization efficiency of 70 to 100% and a very good long time reproducibility of peak area sensitivity: 1.6 to 1.8 s μg{sup −1}. Six and eleven times higher sensitivity, respectively, was provided by atomizers with longer light paths in the observation volume, i.e. externally heated T-tube and externally heated flame-in-T-tube. The latter one, offering limit of detection below 0.01 μg ml{sup −1}, appeared as the most prospective for on-line atomization. Insight into the mechanism of atomization of gold volatile species, into the fate of free atoms and into subsequent analyte transfer allowed to assess possibilities of in-atomizer preconcentration of gold volatile species: it is unfeasible with quartz atomizers but a sapphire tube atomizer could be useful in this respect. - Highlights: • On-line atomization of gold volatile species for AAS in quartz devices was studied. • Atomization mechanism was proposed and atomization efficiency was estimated. • Possibilities of in-atomizer preconcentration of gold volatile species were assessed.

  2. RFID and Memory Devices Fabricated Integrally on Substrates

    Science.gov (United States)

    Schramm, Harry F.

    2004-01-01

    Electronic identification devices containing radio-frequency identification (RFID) circuits and antennas would be fabricated integrally with the objects to be identified, according to a proposal. That is to say, the objects to be identified would serve as substrates for the deposition and patterning of the materials of the devices used to identify them, and each identification device would be bonded to the identified object at the molecular level. Vacuum arc vapor deposition (VAVD) is the NASA derived process for depositing layers of material on the substrate. This proposal stands in contrast to the current practice of fabricating RFID and/or memory devices as wafer-based, self-contained integrated-circuit chips that are subsequently embedded in or attached to plastic cards to make smart account-information cards and identification badges. If one relies on such a chip to store data on the history of an object to be tracked and the chip falls off or out of the object, then one loses both the historical data and the means to track the object and verify its identity electronically. Also, in contrast is the manufacturing philosophy in use today to make many memory devices. Today s methods involve many subtractive processes such as etching. This proposal only uses additive methods, building RFID and memory devices from the substrate up in thin layers. VAVD is capable of spraying silicon, copper, and other materials commonly used in electronic devices. The VAVD process sprays most metals and some ceramics. The material being sprayed has a very strong bond with the substrate, whether that substrate is metal, ceramic, or even wood, rock, glass, PVC, or paper. An object to be tagged with an identification device according to the proposal must be compatible with a vacuum deposition process. Temperature is seldom an issue as the substrate rarely reaches 150 F (66 C) during the deposition process. A portion of the surface of the object would be designated as a substrate for

  3. A flexible organic resistance memory device for wearable biomedical applications

    Science.gov (United States)

    Cai, Yimao; Tan, Jing; YeFan, Liu; Lin, Min; Huang, Ru

    2016-07-01

    Parylene is a Food and Drug Administration (FDA)-approved material which can be safely used within the human body and it is also offers chemically inert and flexible merits. Here, we present a flexible parylene-based organic resistive random access memory (RRAM) device suitable for wearable biomedical application. The proposed device is fabricated through standard lithography and pattern processes at room temperature, exhibiting the feasibility of integration with CMOS circuits. This organic RRAM device offers a high storage window (>104), superior retention ability and immunity to disturbing. In addition, brilliant mechanical and electrical stabilities of this device are demonstrated when under harsh bending (bending cycle >500, bending radius <10 mm). Finally, the underlying mechanism for resistance switching of this kind of device is discussed, and metallic conducting filament formation and annihilation related to oxidization/redox of Al and Al anions migrating in the parylene layer can be attributed to resistance switching in this device. These advantages reveal the significant potential of parylene-based flexible RRAM devices for wearable biomedical applications.

  4. A flexible organic resistance memory device for wearable biomedical applications.

    Science.gov (United States)

    Cai, Yimao; Tan, Jing; YeFan, Liu; Lin, Min; Huang, Ru

    2016-07-08

    Parylene is a Food and Drug Administration (FDA)-approved material which can be safely used within the human body and it is also offers chemically inert and flexible merits. Here, we present a flexible parylene-based organic resistive random access memory (RRAM) device suitable for wearable biomedical application. The proposed device is fabricated through standard lithography and pattern processes at room temperature, exhibiting the feasibility of integration with CMOS circuits. This organic RRAM device offers a high storage window (>10(4)), superior retention ability and immunity to disturbing. In addition, brilliant mechanical and electrical stabilities of this device are demonstrated when under harsh bending (bending cycle >500, bending radius mechanism for resistance switching of this kind of device is discussed, and metallic conducting filament formation and annihilation related to oxidization/redox of Al and Al anions migrating in the parylene layer can be attributed to resistance switching in this device. These advantages reveal the significant potential of parylene-based flexible RRAM devices for wearable biomedical applications.

  5. Generalized Fractional Processes with Long Memory and Time Dependent Volatility Revisited

    Directory of Open Access Journals (Sweden)

    M. Shelton Peiris

    2016-09-01

    Full Text Available In recent years, fractionally-differenced processes have received a great deal of attention due to their flexibility in financial applications with long-memory. This paper revisits the class of generalized fractionally-differenced processes generated by Gegenbauer polynomials and the ARMA structure (GARMA with both the long-memory and time-dependent innovation variance. We establish the existence and uniqueness of second-order solutions. We also extend this family with innovations to follow GARCH and stochastic volatility (SV. Under certain regularity conditions, we give asymptotic results for the approximate maximum likelihood estimator for the GARMA-GARCH model. We discuss a Monte Carlo likelihood method for the GARMA-SV model and investigate finite sample properties via Monte Carlo experiments. Finally, we illustrate the usefulness of this approach using monthly inflation rates for France, Japan and the United States.

  6. Data Acquisition from Volatile Memory: A Memory Acquisition Tool for Microsoft Windows Vista

    Science.gov (United States)

    2008-12-01

    Digital Forensic Practice , Volume 1 Issue 4 December 2006. [4] Jesse D. Kornblum, Exploiting the Rootkit Paradox with Windows Memory Analysis...George Garner, Forensic Acquisition Utilities http://www.gmgsystemsinc.com/ fau /, date last accessed Nov 2008. [8] Helix 3 – Incident Response, Computer

  7. All-magnetic magnetoresistive random access memory based on four terminal mCell device

    Science.gov (United States)

    Bromberg, D. M.; Sumbul, H. E.; Zhu, J.-G.; Pileggi, L.

    2015-05-01

    Magnetoresistive random access memory (MRAM) is a promising candidate to enable fast, non-volatile storage on chip. In this paper, we present an MRAM design where each bitcell is comprised entirely of four-terminal magnetic devices ("mCells") with no CMOS access transistors. We show that this design can achieve significant energy and area savings compared to the standard one transistor-one magnetic tunnel junction (1T1MTJ) bitcell based design. We estimate a write energy of ≈5 fJ/bit based on bitline and wordline voltages that operate at less than 100 mV with projected area smaller than that possible with aggressively scaled 10 nm node FinFETs in the 1T1MTJ design.

  8. Poly (vinylidene fluoride-trifluoroethylene/barium titanate nanocomposite for ferroelectric nonvolatile memory devices

    Directory of Open Access Journals (Sweden)

    Uvais Valiyaneerilakkal

    2013-04-01

    Full Text Available The effect of barium titanate (BaTiO3 nanoparticles (particle size <100nm on the ferroelectric properties of poly (vinylidenefluoride-trifluoroethylene P(VDF-TrFE copolymer has been studied. Different concentrations of nanoparticles were added to P(VDF-TrFE using probe sonication, and uniform thin films were made. Polarisation - Electric field (P-E hysteresis analysis shows an increase in remnant polarization (Pr and decrease in coercive voltage (Vc. Piezo-response force microscopy analysis shows the switching capability of the polymer composite. The topography and surface roughness was studied using atomic force microscopy. It has been observed that this nanocomposite can be used for the fabrication of non-volatile ferroelectric memory devices.

  9. A triple quantum dot based nano-electromechanical memory device

    Energy Technology Data Exchange (ETDEWEB)

    Pozner, R.; Lifshitz, E. [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Peskin, U., E-mail: uri@tx.technion.ac.il [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Lise Meitner Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

    2015-09-14

    Colloidal quantum dots (CQDs) are free-standing nano-structures with chemically tunable electronic properties. This tunability offers intriguing possibilities for nano-electromechanical devices. In this work, we consider a nano-electromechanical nonvolatile memory (NVM) device incorporating a triple quantum dot (TQD) cluster. The device operation is based on a bias induced motion of a floating quantum dot (FQD) located between two bound quantum dots (BQDs). The mechanical motion is used for switching between two stable states, “ON” and “OFF” states, where ligand-mediated effective interdot forces between the BQDs and the FQD serve to hold the FQD in each stable position under zero bias. Considering realistic microscopic parameters, our quantum-classical theoretical treatment of the TQD reveals the characteristics of the NVM.

  10. Resistive switching characteristics and mechanisms in silicon oxide memory devices

    Science.gov (United States)

    Chang, Yao-Feng; Fowler, Burt; Chen, Ying-Chen; Zhou, Fei; Wu, Xiaohan; Chen, Yen-Ting; Wang, Yanzhen; Xue, Fei; Lee, Jack C.

    2016-05-01

    Intrinsic unipolar SiOx-based resistance random access memories (ReRAM) characterization, switching mechanisms, and applications have been investigated. Device structures, material compositions, and electrical characteristics are identified that enable ReRAM cells with high ON/OFF ratio, low static power consumption, low switching power, and high readout-margin using complementary metal-oxide semiconductor transistor (CMOS)-compatible SiOx-based materials. These ideas are combined with the use of horizontal and vertical device structure designs, composition optimization, electrical control, and external factors to help understand resistive switching (RS) mechanisms. Measured temperature effects, pulse response, and carrier transport behaviors lead to compact models of RS mechanisms and energy band diagrams in order to aid the development of computer-aided design for ultralarge-v scale integration. This chapter presents a comprehensive investigation of SiOx-based RS characteristics and mechanisms for the post-CMOS device era.

  11. Long memory volatility of gold price returns: How strong is the evidence from distinct economic cycles?

    Science.gov (United States)

    Bentes, Sonia R.

    2016-02-01

    This paper examines the long memory behavior in the volatility of gold returns using daily data for the period 1985-2009. We divided the whole sample into eight sub-samples in order to analyze the robustness and consistency of our results during different crisis periods. This constitutes our main contribution. We cover four major world crises, namely, (i) the US stock market crash of 1987; (ii) the Asian financial crisis of 1997; (iii) the World Trade Center terrorist attack of 2001 and finally, (iv) the sub-prime crisis of 2007, in order to investigate how the fractional integrated parameter of the FIGARCH(1, d,1) model evolves over time. Our findings are twofold: (i) there is evidence of long memory in the conditional variance over the whole sample period; (ii) when we consider the sub-sample analysis, the results show mixed evidence. Thus, for the 1985-2003 period the long memory parameter is positive and statistically significant in the pre-crisis sub-samples, and there is no evidence of long memory in the crisis sub-sample periods; however the reverse pattern occurs for the 2005-2009 period. This highlights the unique characteristics of the 2007 sub-prime crisis.

  12. A Compute Capable SSD Architecture for Next-Generation Non-volatile Memories

    Energy Technology Data Exchange (ETDEWEB)

    De, Arup [Univ. of California, San Diego, CA (United States)

    2014-01-01

    Existing storage technologies (e.g., disks and ash) are failing to cope with the processor and main memory speed and are limiting the overall perfor- mance of many large scale I/O or data-intensive applications. Emerging fast byte-addressable non-volatile memory (NVM) technologies, such as phase-change memory (PCM), spin-transfer torque memory (STTM) and memristor are very promising and are approaching DRAM-like performance with lower power con- sumption and higher density as process technology scales. These new memories are narrowing down the performance gap between the storage and the main mem- ory and are putting forward challenging problems on existing SSD architecture, I/O interface (e.g, SATA, PCIe) and software. This dissertation addresses those challenges and presents a novel SSD architecture called XSSD. XSSD o oads com- putation in storage to exploit fast NVMs and reduce the redundant data tra c across the I/O bus. XSSD o ers a exible RPC-based programming framework that developers can use for application development on SSD without dealing with the complication of the underlying architecture and communication management. We have built a prototype of XSSD on the BEE3 FPGA prototyping system. We implement various data-intensive applications and achieve speedup and energy ef- ciency of 1.5-8.9 and 1.7-10.27 respectively. This dissertation also compares XSSD with previous work on intelligent storage and intelligent memory. The existing ecosystem and these new enabling technologies make this system more viable than earlier ones.

  13. Self-assembled nanostructured resistive switching memory devices fabricated by templated bottom-up growth.

    Science.gov (United States)

    Song, Ji-Min; Lee, Jang-Sik

    2016-01-07

    Metal-oxide-based resistive switching memory device has been studied intensively due to its potential to satisfy the requirements of next-generation memory devices. Active research has been done on the materials and device structures of resistive switching memory devices that meet the requirements of high density, fast switching speed, and reliable data storage. In this study, resistive switching memory devices were fabricated with nano-template-assisted bottom up growth. The electrochemical deposition was adopted to achieve the bottom-up growth of nickel nanodot electrodes. Nickel oxide layer was formed by oxygen plasma treatment of nickel nanodots at low temperature. The structures of fabricated nanoscale memory devices were analyzed with scanning electron microscope and atomic force microscope (AFM). The electrical characteristics of the devices were directly measured using conductive AFM. This work demonstrates the fabrication of resistive switching memory devices using self-assembled nanoscale masks and nanomateirals growth from bottom-up electrochemical deposition.

  14. Homo-junction ferroelectric field-effect-transistor memory device using solution-processed lithium-doped zinc oxide thin films

    KAUST Repository

    Nayak, Pradipta K.

    2012-06-22

    High performance homo-junction field-effect transistor memory devices were prepared using solution processed transparent lithium-doped zinc oxide thin films for both the ferroelectric and semiconducting active layers. A highest field-effect mobility of 8.7 cm2/Vs was obtained along with an Ion/Ioff ratio of 106. The ferroelectric thin filmtransistors showed a low sub-threshold swing value of 0.19 V/dec and a significantly reduced device operating voltage (±4 V) compared to the reported hetero-junction ferroelectrictransistors, which is very promising for low-power non-volatile memory applications.

  15. Working memory for sequences of temporal durations reveals a volatile single-item store

    Directory of Open Access Journals (Sweden)

    Sanjay G Manohar

    2016-10-01

    remembered better when more items were expected, but worse when irrelevant features were present. This suggests that the privileged state of one item in memory is particularly volatile and susceptible to interference.

  16. Role of hydrogen in volatile behaviour of defects in SiO2-based electronic devices

    Science.gov (United States)

    Wimmer, Yannick; El-Sayed, Al-Moatasem; Gös, Wolfgang; Grasser, Tibor; Shluger, Alexander L.

    2016-06-01

    Charge capture and emission by point defects in gate oxides of metal-oxide-semiconductor field-effect transistors (MOSFETs) strongly affect reliability and performance of electronic devices. Recent advances in experimental techniques used for probing defect properties have led to new insights into their characteristics. In particular, these experimental data show a repeated dis- and reappearance (the so-called volatility) of the defect-related signals. We use multiscale modelling to explain the charge capture and emission as well as defect volatility in amorphous SiO2 gate dielectrics. We first briefly discuss the recent experimental results and use a multiphonon charge capture model to describe the charge-trapping behaviour of defects in silicon-based MOSFETs. We then link this model to ab initio calculations that investigate the three most promising defect candidates. Statistical distributions of defect characteristics obtained from ab initio calculations in amorphous SiO2 are compared with the experimentally measured statistical properties of charge traps. This allows us to suggest an atomistic mechanism to explain the experimentally observed volatile behaviour of defects. We conclude that the hydroxyl-E' centre is a promising candidate to explain all the observed features, including defect volatility.

  17. A Silicon-Based Ferroelectric Capacitor for Memory Devices

    Institute of Scientific and Technical Information of China (English)

    任天令; 张林涛; 刘理天; 李志坚

    2002-01-01

    We study a silicon-based Pb TiO3/Pb(Zro.53 Tio.47)O3/Pb TiO3 capacitor, prepared by an improved sol-gel method.The ferroelectric capacitor has a high remanent polarization of 15 pC/crm2 at a coercive field of about 30 k V/cm,an ultra-low leakage current density of 0.1 hA/crm2, and almost fatigue free properties. It can be used as a promising candidate for ferroelectric memory devices.

  18. Silicon photonic integrated circuits with electrically programmable non-volatile memory functions.

    Science.gov (United States)

    Song, J-F; Lim, A E-J; Luo, X-S; Fang, Q; Li, C; Jia, L X; Tu, X-G; Huang, Y; Zhou, H-F; Liow, T-Y; Lo, G-Q

    2016-09-19

    Conventional silicon photonic integrated circuits do not normally possess memory functions, which require on-chip power in order to maintain circuit states in tuned or field-configured switching routes. In this context, we present an electrically programmable add/drop microring resonator with a wavelength shift of 426 pm between the ON/OFF states. Electrical pulses are used to control the choice of the state. Our experimental results show a wavelength shift of 2.8 pm/ms and a light intensity variation of ~0.12 dB/ms for a fixed wavelength in the OFF state. Theoretically, our device can accommodate up to 65 states of multi-level memory functions. Such memory functions can be integrated into wavelength division mutiplexing (WDM) filters and applied to optical routers and computing architectures fulfilling large data downloading demands.

  19. Design of two crushing devices for release of the fluid inclusion volatiles

    Science.gov (United States)

    Dublyansky, Yuri

    2012-06-01

    Two crushing cells have been described for the release of volatiles from fluid inclusions in minerals in vacuum, static gas, and gas-flow applications. To minimize the adsorption of released volatiles on the freshly created mineral surfaces, both devices employed heated crushing. In the MTSN (Museo Tridentine di Scienze Naturali) crusher, samples were disintegrated by a piston driven by an induction coil. For efficient crushing, the electromagnet operated in dynamic impulse mode. In the LFU (Leopold-Franzens-Universität) crusher, the sample was disintegrated through the combined action of compression (manually operated hydraulic ram) and attrition. Crushers are able to be used in off-line and on-line modes, in gas chromatographic and mass spectrometric analyses.

  20. Selected Advances in Nanoelectronic Devices Logic, Memory and RF

    CERN Document Server

    Joodaki, Mojtaba

    2013-01-01

    Nanoelectronics, as a true successor of microelectronics, is certainly a major technology boomer in the 21st century. This has been shown by its several applications and also by its enormous potential to influence all areas of electronics, computers, information technology, aerospace defense, and consumer goods. Although the current semiconductor technology is projected to reach its physical limit in about a decade, nanoscience and nanotechnology promise breakthroughs for the future. The present books provides an in-depth review of the latest advances in the technology of nanoelectronic devices and their developments over the past decades. Moreover, it introduces new concepts for the realization of future nanoelectronic devices. The main focus of the book is on three fundamental branches of semiconductor products or applications: logic, memory, and RF and communication. By pointing out to the key technical challenges, important aspects and characteristics of various designs are used to illustrate mechanisms t...

  1. Novel nano materials for high performance logic and memory devices

    Science.gov (United States)

    Das, Saptarshi

    After decades of relentless progress, the silicon CMOS industry is approaching a stall in device performance for both logic and memory devices due to fundamental scaling limitations. In order to reinforce the accelerating pace, novel materials with unique properties are being proposed on an urgent basis. This list includes one dimensional nanotubes, quasi one dimensional nanowires, two dimensional atomistically thin layered materials like graphene, hexagonal boron nitride and the more recently the rich family of transition metal di-chalcogenides comprising of MoS2, WSe2, WS2 and many more for logic applications and organic and inorganic ferroelectrics, phase change materials and magnetic materials for memory applications. Only time will tell who will win, but exploring these novel materials allow us to revisit the fundamentals and strengthen our understanding which will ultimately be beneficial for high performance device design. While there has been growing interest in two-dimensional (2D) crystals other than graphene, evaluating their potential usefulness for electronic applications is still in its infancies due to the lack of a complete picture of their performance potential. The fact that the 2-D layered semiconducting di-chalcogenides need to be connected to the "outside" world in order to capitalize on their ultimate potential immediately emphasizes the importance of a thorough understanding of the contacts. This thesis demonstrate that through a proper understanding and design of source/drain contacts and the right choice of number of MoS2 layers the excellent intrinsic properties of this 2D material can be harvested. A comprehensive experimental study on the dependence of carrier mobility on the layer thickness of back gated multilayer MoS 2 field effect transistors is also provided. A resistor network model that comprises of Thomas-Fermi charge screening and interlayer coupling is used to explain the non-monotonic trend in the extracted field effect

  2. Process qualification strategy for advances embedded non volatile memory technology - the Philips'0.18um embedded flash case

    NARCIS (Netherlands)

    Tao, Guoqiao; Scarpa, Andrea; Dijk, van Kitty; Kuper, Fred G.

    2003-01-01

    A qualification strategy for advanced embedded non-volatile memory technology has been revealed. This strategy consists of: a thorough understanding of the requirements, extensive use and frequent update of the FMEA (failure mode effect analysis), a qualification plan with excellent coverage of all

  3. Long Memory and Structural Breaks in Realized Volatility: An Irreversible Markov Switching Approach

    DEFF Research Database (Denmark)

    Nonejad, Nima

    This paper proposes a model that simultaneously captures long memory and structural breaks. We model structural breaks through irreversible Markov switching or so-called change-point dynamics. The parameters subject to structural breaks and the unobserved states which determine the position...... of the structural breaks are sampled from the joint posterior density by sampling from their respective conditional posteriors using Gibbs sampling and Metropolis-Hastings. Monte Carlo simulations demonstrate that the proposed estimation approach is effective in identifying and dating structural breaks. Applied...... to daily S&P 500 data, one finds strong evidence of three structural breaks. The evidence of these breaks is robust to different specifications including a GARCH specification for the conditional variance of volatility....

  4. Brain-like associative learning using a nanoscale non-volatile phase change synaptic device array

    Directory of Open Access Journals (Sweden)

    Sukru Burc Eryilmaz

    2014-07-01

    Full Text Available Recent advances in neuroscience together with nanoscale electronic device technology have resulted in huge interests in realizing brain-like computing hardwares using emerging nanoscale memory devices as synaptic elements. Although there has been experimental work that demonstrated the operation of nanoscale synaptic element at the single device level, network level studies have been limited to simulations. In this work, we demonstrate, using experiments, array level associative learning using phase change synaptic devices connected in a grid like configuration similar to the organization of the biological brain. Implementing Hebbian learning with phase change memory cells, the synaptic grid was able to store presented patterns and recall missing patterns in an associative brain-like fashion. We found that the system is robust to device variations, and large variations in cell resistance states can be accommodated by increasing the number of training epochs. We illustrated the tradeoff between variation tolerance of the network and the overall energy consumption, and found that energy consumption is decreased significantly for lower variation tolerance.

  5. Organic ferroelectric opto-electronic memories

    NARCIS (Netherlands)

    Asadi, K.; Li, M.; Blom, P.W.M.; Kemerink, M.; Leeuw, D.M. de

    2011-01-01

    Memory is a prerequisite for many electronic devices. Organic non-volatile memory devices based on ferroelectricity are a promising approach towards the development of a low-cost memory technology based on a simple cross-bar array. In this review article we discuss the latest developments in this ar

  6. Scaling dependence of memory windows and different carrier charging behaviors in Si nanocrystal nonvolatile memory devices

    Science.gov (United States)

    Yu, Jie; Chen, Kun-ji; Ma, Zhong-yuan; Zhang, Xin-xin; Jiang, Xiao-fan; Wu, Yang-qing; Huang, Xin-fan; Oda, Shunri

    2016-09-01

    Based on the charge storage mode, it is important to investigate the scaling dependence of memory performance in silicon nanocrystal (Si-NC) nonvolatile memory (NVM) devices for its scaling down limit. In this work, we made eight kinds of test key cells with different gate widths and lengths by 0.13-μm node complementary metal oxide semiconductor (CMOS) technology. It is found that the memory windows of eight kinds of test key cells are almost the same of about 1.64 V @ ± 7 V/1 ms, which are independent of the gate area, but mainly determined by the average size (12 nm) and areal density (1.8 × 1011/cm2) of Si-NCs. The program/erase (P/E) speed characteristics are almost independent of gate widths and lengths. However, the erase speed is faster than the program speed of test key cells, which is due to the different charging behaviors between electrons and holes during the operation processes. Furthermore, the data retention characteristic is also independent of the gate area. Our findings are useful for further scaling down of Si-NC NVM devices to improve the performance and on-chip integration. Project supported by the State Key Development Program for Basic Research of China (Grant No. 2010CB934402) and the National Natural Science Foundation of China (Grant Nos. 11374153, 61571221, and 61071008).

  7. Random Access Memory Technologies.

    Science.gov (United States)

    1985-02-01

    extreme temperatures. True nonvolatility is offered by the NVRAM or shadow RAM. In the NVRAM , a volatile NMOS static RAM memory cell is merged with the...or reapplied, and no longer require special power sources. The size of the nine-device memory cell required for the NVRAM has limited its capacity to...4K. While 8K NVRAMs are expected in 1985, the 30 . . .’o .-. . high cost of these devices will hamper further development for larger capacity memories

  8. Integration of lead-free ferroelectric on HfO2/Si (100) for high performance non-volatile memory applications

    Science.gov (United States)

    Kundu, Souvik; Maurya, Deepam; Clavel, Michael; Zhou, Yuan; Halder, Nripendra N.; Hudait, Mantu K.; Banerji, Pallab; Priya, Shashank

    2015-02-01

    We introduce a novel lead-free ferroelectric thin film (1-x)BaTiO3-xBa(Cu1/3Nb2/3)O3 (x = 0.025) (BT-BCN) integrated on to HfO2 buffered Si for non-volatile memory (NVM) applications. Piezoelectric force microscopy (PFM), x-ray diffraction, and high resolution transmission electron microscopy were employed to establish the ferroelectricity in BT-BCN thin films. PFM study reveals that the domains reversal occurs with 180° phase change by applying external voltage, demonstrating its effectiveness for NVM device applications. X-ray photoelectron microscopy was used to investigate the band alignments between atomic layer deposited HfO2 and pulsed laser deposited BT-BCN films. Programming and erasing operations were explained on the basis of band-alignments. The structure offers large memory window, low leakage current, and high and low capacitance values that were easily distinguishable even after ~106 s, indicating strong charge storage potential. This study explains a new approach towards the realization of ferroelectric based memory devices integrated on Si platform and also opens up a new possibility to embed the system within current complementary metal-oxide-semiconductor processing technology.

  9. Comparative study of CNT, silicon nanowire and fullerene embedded multilayer high-k gate dielectric MOS memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Amretashis; Sarkar, Chandan Kumar [Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata-700 032 (India); Requejo, Felix G, E-mail: amretashis@gmail.com [INIFTA, Departmento de Quimica and Departmento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC/67-1900, La Plata (Argentina)

    2011-10-12

    Here, we present a comparative theoretical study on stacked (multilayer) gate dielectric MOS memory devices, having a metallic/semiconducting carbon nanotube (CNT), silicon nanowire (Si NW) and fullerene (C60) embedded nitride layer acting as a floating gate. Two types of devices, one with HfO{sub 2}-SiO{sub 2} stack (stack-1) and the other with La{sub 2}O{sub 3}-SiO{sub 2} stack (stack-2) as the tunnel oxide were compared. We evaluated the effective barrier height, the dielectric constant and the effective electron mobility in the composite gate dielectric with the Maxwell-Garnett effective medium theory. Thereafter applying the WKB approximation, we simulated the Fowler-Nordheim (F-N) tunnelling/writing current and the direct tunnelling/leakage current in these devices. We evaluated the I-V characteristics, the charge decay and also the impact of CNT/Si NW aspect ratio and the volume fraction on the effective barrier height and the write voltage, respectively. We also simulated the write time, retention time and the erase time of these MOS devices. Based on the simulation results, it was concluded that the metallic CNT embedded stack-1 device offered the best performance in terms of higher F-N tunnelling current, lower direct tunnelling current and lesser write voltage and write time compared with the other devices. In case of direct tunnelling leakage and retention time it was found that the met CNT embedded stack-2 device showed better characteristics. For erasing, however, the C60 embedded stack-1 device showed the smallest erase time. When compared with earlier reports, it was seen that CNT, C60 and Si NW embedded devices all performed better than nanocrystalline Si embedded MOS non-volatile memories.

  10. Semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  11. Long memory of abnormal investor attention and the cross-correlations between abnormal investor attention and trading volume, volatility respectively

    Science.gov (United States)

    Fan, Xiaoqian; Yuan, Ying; Zhuang, Xintian; Jin, Xiu

    2017-03-01

    Taking Baidu Index as a proxy for abnormal investor attention (AIA), the long memory property in the AIA of Shanghai Stock Exchange (SSE) 50 Index component stocks was empirically investigated using detrended fluctuation analysis (DFA) method. The results show that abnormal investor attention is power-law correlated with Hurst exponents between 0.64 and 0.98. Furthermore, the cross-correlations between abnormal investor attention and trading volume, volatility respectively are studied using detrended cross-correlation analysis (DCCA) and the DCCA cross-correlation coefficient (ρDCCA). The results suggest that there are positive correlations between AIA and trading volume, volatility respectively. In addition, the correlations for trading volume are in general higher than the ones for volatility. By carrying on rescaled range analysis (R/S) and rolling windows analysis, we find that the results mentioned above are effective and significant.

  12. SHADE: A Shape-Memory-Activated Device Promoting Ankle Dorsiflexion

    Science.gov (United States)

    Pittaccio, S.; Viscuso, S.; Rossini, M.; Magoni, L.; Pirovano, S.; Villa, E.; Besseghini, S.; Molteni, F.

    2009-08-01

    Acute post-stroke rehabilitation protocols include passive mobilization as a means to prevent contractures. A device (SHADE) that provides repetitive passive motion to a flaccid ankle by using shape memory alloy actuators could be of great help in providing this treatment. A suitable actuator was designed as a cartridge of approximately 150 × 20 × 15 mm, containing 2.5 m of 0.25 mm diameter NiTi wire. This actuator was activated by Joule’s effect employing a 7 s current input at 0.7 A, which provided 10 N through 76 mm displacement. Cooling and reset by natural convection took 30 s. A prototype of SHADE was assembled with two thermoplastic shells hinged together at the ankle and strapped on the shin and foot. Two actuators were fixed on the upper shell while an inextensible thread connected each NiTi wire to the foot shell. The passive ankle motion (passive range of motion, PROM) generated by SHADE was evaluated optoelectronically on three flaccid patients (58 ± 5 years old); acceptability was assessed by a questionnaire presented to further three flaccid patients (44 ± 11.5 years old) who used SHADE for 5 days, 30 min a day. SHADE was well accepted by all patients, produced good PROM, and caused no pain. The results prove that suitable limb mobilization can be produced by SMA actuators.

  13. A motionless actuation system for magnetic shape memory devices

    Science.gov (United States)

    Armstrong, Andrew; Finn, Kevin; Hobza, Anthony; Lindquist, Paul; Rafla, Nader; Müllner, Peter

    2017-10-01

    Ni–Mn–Ga is a Magnetic Shape Memory (MSM) alloy that changes shape in response to a variable magnetic field. We can intentionally manipulate the shape of the material to function as an actuator, and the material can thus replace complicated small electromechanical systems. In previous work, a very simple and precise solid-state micropump was developed, but a mechanical rotation was required to translate the position of the magnetic field. This mechanical rotation defeats the purpose of the motionless solid-state device. Here we present a solid-state electromagnetic driver to linearly progress the position of the applied magnetic field and the associated shrinkage. The generated magnetic field was focused at either of two pole pieces, providing a mechanism for moving the localized shrinkage in the MSM element. We confirmed that our driver has sufficient strength to actuate the MSM element using optical microscopy. We validated the whole design by comparing results obtained with finite element analysis with the experimentally measured flux density. This drive system serves as a possible replacement to the mechanical rotation of the magnetic field by using a multi-pole electromagnet that sweeps the magnetic field across the MSM micropump element, solid-state switching the current to each pole piece in the multi-pole electromagnet.

  14. Resistive switching effect in the planar structure of all-printed, flexible and rewritable memory device based on advanced 2D nanocomposite of graphene quantum dots and white graphene flakes

    Science.gov (United States)

    Muqeet Rehman, Muhammad; Uddin Siddiqui, Ghayas; Kim, Sowon; Choi, Kyung Hyun

    2017-08-01

    Pursuit of the most appropriate materials and fabrication methods is essential for developing a reliable, rewritable and flexible memory device. In this study, we have proposed an advanced 2D nanocomposite of white graphene (hBN) flakes embedded with graphene quantum dots (GQDs) as the functional layer of a flexible memory device owing to their unique electrical, chemical and mechanical properties. Unlike the typical sandwich type structure of a memory device, we developed a cost effective planar structure, to simplify device fabrication and prevent sneak current. The entire device fabrication was carried out using printing technology followed by encapsulation in an atomically thin layer of aluminum oxide (Al2O3) for protection against environmental humidity. The proposed memory device exhibited attractive bipolar switching characteristics of high switching ratio, large electrical endurance and enhanced lifetime, without any crosstalk between adjacent memory cells. The as-fabricated device showed excellent durability for several bending cycles at various bending diameters without any degradation in bistable resistive states. The memory mechanism was deduced to be conductive filamentary; this was validated by illustrating the temperature dependence of bistable resistive states. Our obtained results pave the way for the execution of promising 2D material based next generation flexible and non-volatile memory (NVM) applications.

  15. A NEW DEVICE AND METHOD FOR MEASURING VOLATILE COMPOUNDS IN MONITORING WELLS

    Energy Technology Data Exchange (ETDEWEB)

    Vangelas, K; Warren Hyde, W; Brian02 Looney, B; Kirk Cantrell, K; Tyler Gilmore, T

    2006-11-06

    Accurate, timely measurement of chlorinated solvents and other volatile contaminants in groundwater is crucial to support responsible environmental management. Traditionally, two distinctly different paradigms have been explored to meet this need--fixed laboratory analysis and ''real-time'' sensors. While these alternatives remain important, field based and field screening tools represent a potentially useful intermediate approach that balances some of the advantages and disadvantages of the traditional ''endmember'' paradigms. The value of accurate, in-field measurements during characterization was recognized in recent sampling/decision methods, such as the TRIAD approach (ITRC, 2003). Strategies that support gathering accurate data on the timescales representative of the rate of change of the system (e.g., months to years, not seconds to minutes) is key for long-term monitoring for chlorinated solvent plumes in which attenuation based remedies are being considered. A team of researchers developed a down-well sampling device that, when used in combination with field gas analysis tools, provides data in the field. The test results indicate this tool, as configured, will provide accurate measurements (as compared with laboratory methods) at concentrations in the hundreds of ppb or higher range, but require confirmatory traditional sampling with laboratory analysis at concentrations approaching 20 ppb and less. The logistics and costs of the sampling device were somewhat complex. The results of the study, while equivocal, generally suggest that future development of this type of in-field technique may be warranted.

  16. Different importance of the volatile and non-volatile fractions of an olfactory signature for individual social recognition in rats versus mice and short-term versus long-term memory.

    Science.gov (United States)

    Noack, Julia; Richter, Karin; Laube, Gregor; Haghgoo, Hojjat Allah; Veh, Rüdiger W; Engelmann, Mario

    2010-11-01

    When tested in the olfactory cued social recognition/discrimination test, rats and mice differ in their retention of a recognition memory for a previously encountered conspecific juvenile: Rats are able to recognize a given juvenile for approximately 45 min only whereas mice show not only short-term, but also long-term recognition memory (≥ 24 h). Here we modified the social recognition/social discrimination procedure to investigate the neurobiological mechanism(s) underlying the species differences. We presented a conspecific juvenile repeatedly to the experimental subjects and monitored the investigation duration as a measure for recognition. Presentation of only the volatile fraction of the juvenile olfactory signature was sufficient for both short- and long-term recognition in mice but not rats. Applying additional volatile, mono-molecular odours to the "to be recognized" juveniles failed to affect short-term memory in both species, but interfered with long-term recognition in mice. Finally immunocytochemical analysis of c-Fos as a marker for cellular activation, revealed that juvenile exposure stimulated areas involved in the processing of olfactory signals in both the main and the accessory olfactory bulb in mice. In rats, we measured an increased c-Fos synthesis almost exclusively in cells of the accessory olfactory bulb. Our data suggest that the species difference in the retention of social recognition memory is based on differences in the processing of the volatile versus non-volatile fraction of the individuals' olfactory signature. The non-volatile fraction is sufficient for retaining a short-term social memory only. Long-term social memory - as observed in mice - requires a processing of both the volatile and non-volatile fractions of the olfactory signature. Copyright © 2010 Elsevier Inc. All rights reserved.

  17. Status and Prospects of ZnO-Based Resistive Switching Memory Devices.

    Science.gov (United States)

    Simanjuntak, Firman Mangasa; Panda, Debashis; Wei, Kung-Hwa; Tseng, Tseung-Yuen

    2016-12-01

    In the advancement of the semiconductor device technology, ZnO could be a prospective alternative than the other metal oxides for its versatility and huge applications in different aspects. In this review, a thorough overview on ZnO for the application of resistive switching memory (RRAM) devices has been conducted. Various efforts that have been made to investigate and modulate the switching characteristics of ZnO-based switching memory devices are discussed. The use of ZnO layer in different structure, the different types of filament formation, and the different types of switching including complementary switching are reported. By considering the huge interest of transparent devices, this review gives the concrete overview of the present status and prospects of transparent RRAM devices based on ZnO. ZnO-based RRAM can be used for flexible memory devices, which is also covered here. Another challenge in ZnO-based RRAM is that the realization of ultra-thin and low power devices. Nevertheless, ZnO not only offers decent memory properties but also has a unique potential to be used as multifunctional nonvolatile memory devices. The impact of electrode materials, metal doping, stack structures, transparency, and flexibility on resistive switching properties and switching parameters of ZnO-based resistive switching memory devices are briefly compared. This review also covers the different nanostructured-based emerging resistive switching memory devices for low power scalable devices. It may give a valuable insight on developing ZnO-based RRAM and also should encourage researchers to overcome the challenges.

  18. Status and Prospects of ZnO-Based Resistive Switching Memory Devices

    Science.gov (United States)

    Simanjuntak, Firman Mangasa; Panda, Debashis; Wei, Kung-Hwa; Tseng, Tseung-Yuen

    2016-08-01

    In the advancement of the semiconductor device technology, ZnO could be a prospective alternative than the other metal oxides for its versatility and huge applications in different aspects. In this review, a thorough overview on ZnO for the application of resistive switching memory (RRAM) devices has been conducted. Various efforts that have been made to investigate and modulate the switching characteristics of ZnO-based switching memory devices are discussed. The use of ZnO layer in different structure, the different types of filament formation, and the different types of switching including complementary switching are reported. By considering the huge interest of transparent devices, this review gives the concrete overview of the present status and prospects of transparent RRAM devices based on ZnO. ZnO-based RRAM can be used for flexible memory devices, which is also covered here. Another challenge in ZnO-based RRAM is that the realization of ultra-thin and low power devices. Nevertheless, ZnO not only offers decent memory properties but also has a unique potential to be used as multifunctional nonvolatile memory devices. The impact of electrode materials, metal doping, stack structures, transparency, and flexibility on resistive switching properties and switching parameters of ZnO-based resistive switching memory devices are briefly compared. This review also covers the different nanostructured-based emerging resistive switching memory devices for low power scalable devices. It may give a valuable insight on developing ZnO-based RRAM and also should encourage researchers to overcome the challenges.

  19. FIELD SCREENING FOR HALOGENATED VOLATILE ORGANIC COMPOUNDS: THE NEW X-WAND HVOC SCREENING DEVICE

    Energy Technology Data Exchange (ETDEWEB)

    John F. Schabron; Susan S. Sorini; Joseph F. Rovani Jr

    2006-03-01

    Western Research Institute (WRI) has developed new methodology and a test kit to screen soil or water samples for halogenated volatile organic compounds (HVOCs) in the field. The technology has been designated the X-Wand{trademark} screening tool. The new device uses a heated diode sensor that is commonly used to detect leaks of refrigerants from air conditioners, freezers, and refrigerators. This sensor is selective to halogens. It does not respond to volatile aromatic hydrocarbons, such as those in gasoline, and it is not affected by high humidity. In the current work, the heated diode leak detectors were modified further to provide units with rapid response and enhanced sensitivity. The limit of detection for trichloroethylene TCE in air is 0.1 mg/m{sup 3} (S/N = 2). The response to other HVOCS relative to TCE is similar. Variability between sensors and changes in a particular sensor over time can be compensated for by normalizing sensor readings to a maximum sensor reading at 1,000 mg/m{sup 3} TCE. The soil TCE screening method was expanded to include application to water samples. Assuming complete vaporization, the detection limit for TCE in soil is about 1 ug/kg (ppb) for a 25-g sample in an 8-oz jar. The detection limit for TCE in water is about 1 ug/L (ppb) for a 25-mL sample in an 8-oz jar. This is comparable to quantitation limits of EPA GC/MS laboratory methods. A draft ASTM method for screening TCE contaminated soils using a heated diode sensor was successfully submitted for concurrent main committee and subcommittee balloting in ASTM Committee D 34 on Waste Management. The method was approved as ASTM D 7203-05, Standard Test Method for Screening Trichloroethylene (TCE)-Contaminated Soil Using a Heated Diode Sensor.

  20. Configurable memory system and method for providing atomic counting operations in a memory device

    Science.gov (United States)

    Bellofatto, Ralph E.; Gara, Alan G.; Giampapa, Mark E.; Ohmacht, Martin

    2010-09-14

    A memory system and method for providing atomic memory-based counter operations to operating systems and applications that make most efficient use of counter-backing memory and virtual and physical address space, while simplifying operating system memory management, and enabling the counter-backing memory to be used for purposes other than counter-backing storage when desired. The encoding and address decoding enabled by the invention provides all this functionality through a combination of software and hardware.

  1. Ferroelectric-gate field effect transistor memories device physics and applications

    CERN Document Server

    Ishiwara, Hiroshi; Okuyama, Masanori; Sakai, Shigeki; Yoon, Sung-Min

    2016-01-01

    This book provides comprehensive coverage of the materials characteristics, process technologies, and device operations for memory field-effect transistors employing inorganic or organic ferroelectric thin films. This transistor-type ferroelectric memory has interesting fundamental device physics and potentially large industrial impact. Among the various applications of ferroelectric thin films, the development of nonvolatile ferroelectric random access memory (FeRAM) has progressed most actively since the late 1980s and has achieved modest mass production levels for specific applications since 1995. There are two types of memory cells in ferroelectric nonvolatile memories. One is the capacitor-type FeRAM and the other is the field-effect transistor (FET)-type FeRAM. Although the FET-type FeRAM claims ultimate scalability and nondestructive readout characteristics, the capacitor-type FeRAMs have been the main interest for the major semiconductor memory companies, because the ferroelectric FET has fatal handic...

  2. CD uniformity correction on 45-nm technology non-volatile memory

    Science.gov (United States)

    Buttgereit, Ute; Birkner, Robert; Joyner, Mark; Graitzer, Erez; Cohen, Avi; Miyashita, Hiroyuki; Triulzi, Benedetta; Fasciszewski Zeballos, Alejandro; Romeo, Carmelo

    2010-03-01

    One of the key parameters necessary to assure a good and reliable functionality of any integrated circuit is the Critical Dimension Uniformity (CDU). There are different contributors which impact the total CDU: mask CD uniformity, scanner and lens fingerprint, resist process, wafer topography, mask error enhancement factor (MEEF) etc. In this work we focus on improvement of intra-field CDU at wafer level by improving the mask CD signature using a CDC200TM tool from Carl Zeiss SMS. The mask layout used is a line and space dark level of a 45nm node Non Volatile Memory (NVM). A prerequisite to improve intra-field CDU at wafer level is to characterize the mask CD signature precisely. For CD measurement on mask the newly developed wafer level CD metrology tool WLCD32 of Carl Zeiss SMS was used. The WLCD32 measures CD based on aerial imaging technology. The WLCD32 measurement data show an excellent correlation to wafer CD data. For CDU correction the CDC200TM tool is used. By utilizing an ultrafast femto-second laser the CDC200TM writes intra-volume shading elements (Shade-In ElementsTM) inside the bulk of the mask. By adjusting the density of the shading elements, the light transmission through the mask is locally changed in a manner that improves wafer CDU when the corrected mask is printed. In the present work we will demonstrate a closed loop process of WLCD32 and CDC200TM to improve mask CD signature as one of the main contributors to intra-field wafer CDU.

  3. Nonvolatile write-once-read-many-times memory device with functionalized-nanoshells/PEDOT:PSS nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Avila-Nino, J.A.; Segura-Cardenas, E. [Universidad Autonoma de San Luis Potosi, Instituto de Investigacion en Comunicacion Optica, Alvaro Obregon 64 Zona Centro, 78000 SLP (Mexico); Sustaita, A.O. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, CP 78216, San Luis Potosi (Mexico); Cruz-Cruz, I. [Universidad Autonoma de San Luis Potosi, Instituto de Investigacion en Comunicacion Optica, Alvaro Obregon 64 Zona Centro, 78000 SLP (Mexico); Lopez-Sandoval, R. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, CP 78216, San Luis Potosi (Mexico); Reyes-Reyes, M., E-mail: reyesm@iico.uaslp.mx [Universidad Autonoma de San Luis Potosi, Instituto de Investigacion en Comunicacion Optica, Alvaro Obregon 64 Zona Centro, 78000 SLP (Mexico)

    2011-03-25

    We have investigated the memory effect of the nanocomposites of functionalized carbon nanoshells (f-CNSs) mixed with poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonate (PEDOT:PSS) polymer. The f-CNSs were synthesized by the spray pyrolysis method and functionalized in situ with functional groups (OH, COOH, C-H, C-OH) with the aim of improving their compatibility in the aqueous dispersion of PEDOT:PSS. The current-voltage (I-V) sweep curves at room temperature for the Al/f-CNSs, for certain concentrations range, embedded in a PEDOT:PSS layer/Al devices showed electrical bistability for write-once-read-many-times (WORM) memory devices. The memory effect observed in the devices can be explained due to the existence of trapped charges in the f-CNSs/PEDOT:PSS layer. The carrier transport mechanisms for the memory devices is studied and discussed.

  4. Fixation of external drainage device with injectable shape-memory alloy clips.

    Science.gov (United States)

    Olson, Jeffrey L; Erlanger, Michael

    2013-09-01

    To describe a novel surgical technique and novel surgical instrumentation for fixating an extraocular drainage device used for glaucoma-filtering surgery. The technique was performed in a laboratory setting using ex-vivo porcine eyes. We describe the surgical technique of using injectable, 25-gauge shape-memory clip system to fixate an Ahmed drainage device. The use of an injectable, shape-memory alloy clip provides the advantages of rapid, easy deployment and decreased risk of late suture failure. Importantly, the injectable, shape-memory clips can be used in surgical situations where suturing is difficult and time intensive, such as those encountered during glaucoma drainage device placement. The use of an injectable, shape-memory alloy clip is a promising new surgical tool and technique for fixating an extraocular drainage device used for glaucoma surgery.

  5. Market memory and fat tail consequences in option pricing on the expOU stochastic volatility model

    CERN Document Server

    Perello, J

    2006-01-01

    The expOU stochastic volatility model is capable of reproducing fairly well most important statistical properties of financial markets daily data. Among them, the presence of multiple time scales in the volatility autocorrelation is perhaps the most relevant which makes appear fat tails in the return distributions. This paper wants to go further on with the expOU model we have studied in Ref. 1 by exploring an aspect of practical interest. Having as a benchmark the parameters estimated from the Dow Jones daily data, we want to compute the price for the European option. This is actually done by Monte Carlo, running a large number of simulations. Our main interest is to "see" the effects of a long-range market memory from our expOU model in its subsequent European call option. We pay attention to the effects of the existence of a broad range of time scales in the volatility. We find that a richer set of time scales brings to a higher price of the option. This appears in clear contrast to the presence of memory ...

  6. Market memory and fat tail consequences in option pricing on the expOU stochastic volatility model

    Science.gov (United States)

    Perelló, Josep

    2007-08-01

    The expOU stochastic volatility model is capable of reproducing fairly well most important statistical properties of financial markets daily data. Among them, the presence of multiple time scales in the volatility autocorrelation is perhaps the most relevant which makes appear fat tails in the return distributions. This paper wants to go further on with the expOU model we have studied in Ref. [J. Masoliver, J. Perelló, Quant. Finance 6 (2006) 423] by exploring an aspect of practical interest. Having as a benchmark the parameters estimated from the Dow Jones daily data, we want to compute the price for the European option. This is actually done by Monte Carlo, running a large number of simulations. Our main interest is to “see” the effects of a long-range market memory from our expOU model in its subsequent European call option. We pay attention to the effects of the existence of a broad range of time scales in the volatility. We find that a richer set of time scales brings the price of the option higher. This appears in clear contrast to the presence of memory in the price itself which makes the price of the option cheaper.

  7. Observation of long term potentiation in papain-based memory devices

    KAUST Repository

    Bag, A.

    2014-06-01

    Biological synaptic behavior in terms of long term potentiation has been observed in papain-based (plant protein) memory devices (memristors) for the first time. Improvement in long term potentiation depends on pulse amplitude and width (duration). Continuous/repetitive dc voltage sweep leads to an increase in memristor conductivity leading to a long term memory in the \\'learning\\' processes.

  8. Multiterminal Memristive Nanowire Devices for Logic and Memory Applications: A Review

    OpenAIRE

    Sacchetto, Davide; De Micheli, Giovanni; Leblebici, Yusuf

    2012-01-01

    Memristive devices have the potential for a complete renewal of the electron devices landscape, including memory, logic, and sensing applications. This is especially true when considering that the memristive functionality is not limited to two-terminal devices, whose practical realization has been demonstrated within a broad range of different technologies. For electron devices, the memristive functionality can be generally attributed to a material state modification, whose dynamics can be en...

  9. Piezoelectric control of magnetoelectric coupling driven non-volatile memory switching and self cooling effects in FE/FSMA multiferroic heterostructures

    Science.gov (United States)

    Singh, Kirandeep; Kaur, Davinder

    2017-02-01

    The manipulation of magnetic states and materials' spin degree-of-freedom via a control of an electric (E-) field has been recently pursued to develop magnetoelectric (ME) coupling-driven electronic data storage devices with high read/write endurance, fast dynamic response, and low energy dissipation. One major hurdle for this approach is to develop reliable materials which should be compatible with prevailing silicon (Si)-based complementary metal-oxide-semiconductor (CMOS) technology, simultaneously allowing small voltage for the tuning of magnetization switching. In this regard, multiferroic heterostructures where ferromagnetic (FM) and ferroelectric (FE) layers are alternatively grown on conventional Si substrates are promising as the piezoelectric control of magnetization switching is anticipated to be possible by an E-field. In this work, we study the ferromagnetic shape memory alloys based PbZr0.52Ti0.48O3/Ni50Mn35In15 (PZT/Ni-Mn-In) multiferroic heterostructures, and investigate their potential for CMOS compatible non-volatile magnetic data storage applications. We demonstrate the voltage-impulse controlled nonvolatile, reversible, and bistable magnetization switching at room temperature in Si-integrated PZT/Ni-Mn-In thin film multiferroic heterostructures. We also thoroughly unveil the various intriguing features in these materials, such as E-field tuned ME coupling and magnetocaloric effect, shape memory induced ferroelectric modulation, improved fatigue endurance as well as Refrigeration Capacity (RC). This comprehensive study suggests that these novel materials have a great potential for the development of unconventional nanoscale memory and refrigeration devices with self-cooling effect and enhanced refrigeration efficiency, thus providing a new venue for their applications.

  10. High-Performance Flexible Organic Nano-Floating Gate Memory Devices Functionalized with Cobalt Ferrite Nanoparticles.

    Science.gov (United States)

    Jung, Ji Hyung; Kim, Sunghwan; Kim, Hyeonjung; Park, Jongnam; Oh, Joon Hak

    2015-10-07

    Nano-floating gate memory (NFGM) devices are transistor-type memory devices that use nanostructured materials as charge trap sites. They have recently attracted a great deal of attention due to their excellent performance, capability for multilevel programming, and suitability as platforms for integrated circuits. Herein, novel NFGM devices have been fabricated using semiconducting cobalt ferrite (CoFe2O4) nanoparticles (NPs) as charge trap sites and pentacene as a p-type semiconductor. Monodisperse CoFe2O4 NPs with different diameters have been synthesized by thermal decomposition and embedded in NFGM devices. The particle size effects on the memory performance have been investigated in terms of energy levels and particle-particle interactions. CoFe2O4 NP-based memory devices exhibit a large memory window (≈73.84 V), a high read current on/off ratio (read I(on)/I(off)) of ≈2.98 × 10(3), and excellent data retention. Fast switching behaviors are observed due to the exceptional charge trapping/release capability of CoFe2O4 NPs surrounded by the oleate layer, which acts as an alternative tunneling dielectric layer and simplifies the device fabrication process. Furthermore, the NFGM devices show excellent thermal stability, and flexible memory devices fabricated on plastic substrates exhibit remarkable mechanical and electrical stability. This study demonstrates a viable means of fabricating highly flexible, high-performance organic memory devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Fabrication of Nano-Crossbar Resistive Switching Memory Based on the Copper-Tantalum Pentoxide-Platinum Device Structure

    Science.gov (United States)

    Olga Gneri, Paula; Jardim, Marcos

    Resistive switching memory has been of interest lately not only for its simple metal-insulator-metal (MIM) structure but also for its promising ease of scalability an integration into current CMOS technologies like the Field Programmable Gate Arrays and other non-volatile memory applications. There are several resistive switching MIM combinations but under this scope of research, attention will be paid to the bipolar resistive switching characteristics and fabrication of Tantalum Pentaoxide sandwiched between platinum and copper. By changing the polarity of the voltage bias, this metal-insulator-metal (MIM) device can be switched between a high resistive state (OFF) and low resistive state (ON). The change in states is induced by an electrochemical metallization process, which causes a formation or dissolution of Cu metal filamentary paths in the Tantalum Pentaoxide insulator. There is very little thorough experimental information about the Cu-Ta 2O5-Pt switching characteristics when scaled to nanometer dimensions. In this light, the MIM structure was fabricated in a two-dimensional crossbar format. Also, with the limited available resources, a multi-spacer technique was formulated to localize the active device area in this MIM configuration to less than 20nm. This step is important in understanding the switching characteristics and reliability of this structure when scaled to nanometer dimensions.

  12. Performance Measurement of a Multi-Level/Analog Ferroelectric Memory Device Design

    Science.gov (United States)

    MacLeod, Todd C.; Phillips, Thomas A.; Ho, Fat D.

    2007-01-01

    Increasing the memory density and utilizing the unique characteristics of ferroelectric devices is important in making ferroelectric memory devices more desirable to the consumer. This paper describes the characterization of a design that allows multiple levels to be stored in a ferroelectric based memory cell. It can be used to store multiple bits or analog values in a high speed nonvolatile memory. The design utilizes the hysteresis characteristic of ferroelectric transistors to store an analog value in the memory cell. The design also compensates for the decay of the polarization of the ferroelectric material over time. This is done by utilizing a pair of ferroelectric transistors to store the data. One transistor is used a reference to determinethe amount of decay that has occurred since the pair was programmed. The second transistor stores the analog value as a polarization value between zero and saturated. The design allows digital data to be stored as multiple bits in each memory cell. The number of bits per cell that can be stored will vary with the decay rate of the ferroelectric transistors and the repeatability of polarization between transistors. This paper presents measurements of an actual prototype memory cell. This prototype is not a complete implementation of a device, but instead, a prototype of the storage and retrieval portion of an actual device. The performance of this prototype is presented with the projected performance of the overall device. This memory design will be useful because it allows higher memory density, compensates for the environmental and ferroelectric aging processes, allows analog values to be directly stored in memory, compensates for the thermal and radiation environments associated with space operations, and relies only on existing technologies.

  13. Design of a Molecular Memory Device: The Electron Transfer Shift Register Memory

    Science.gov (United States)

    Beratan, D.

    1993-01-01

    A molecular shift register memory at the molecular level is described. The memory elements consist of molecules can exit in either an oxidized or reduced state and the bits are shifted between the cells with photoinduced electron transfer reactions.

  14. Miniaturized vortex transitional Josephson memory cell by a vertically integrated device structure

    Energy Technology Data Exchange (ETDEWEB)

    Nagasawa, Shuichi; Tahara, Shuichi; Numata, Hideaki; Tsuchida, Sanae (NEC Corp., Tsukuba (Japan))

    1994-03-01

    We have developed the smallest Josephson nondestructive read-out (NDRO) memory cell, called a vortex transitional (VT) memory cell, for a Josephson high-speed 16-Kbit RAM. Its size is 22 x 22 microns(sup 2), which is only 16% of the size of previously developed VT memory cells used in Josephson 4-Kbit RAM. This is achieved by developing a vertically integrated device structure and refining small-junction technology. The cell consists of Nb/AlO(sub x)/Nb junctions, three Nb wirings, SiO2 insulators and Mo resistors. The VT memory cells operate properly, with a large operating margin of +/- 20%. 13 refs.

  15. Memory operation devices based on light-illumination ambipolar carbon-nanotube thin-film-transistors

    Energy Technology Data Exchange (ETDEWEB)

    Aïssa, B., E-mail: aissab@emt.inrs.ca [Qatar Environment and Energy Research Institute (QEERI), Qatar Foundation, P.O. Box 5825, Doha (Qatar); Centre Energie, Matériaux et Télécommunications, INRS, 1650, Boulevard Lionel-Boulet Varennes, Quebec J3X 1S2 (Canada); Nedil, M. [Telebec Wireless Underground Communication Laboratory, UQAT, 675, 1ère Avenue, Val d' Or, Quebec J9P 1Y3 (Canada); Kroeger, J. [NanoIntegris & Raymor Nanotech, Raymor Industries Inc., 3765 La Vérendrye, Boisbriand, Quebec J7H 1R8 (Canada); Haddad, T. [Department of Mechanical Engineering, McGill University, Montreal, Quebec H3A 0B8 (Canada); Rosei, F. [Centre Energie, Matériaux et Télécommunications, INRS, 1650, Boulevard Lionel-Boulet Varennes, Quebec J3X 1S2 (Canada)

    2015-09-28

    We report the memory operation behavior of a light illumination ambipolar single-walled carbon nanotube thin film field-effect transistors devices. In addition to the high electronic-performance, such an on/off transistor-switching ratio of 10{sup 4} and an on-conductance of 18 μS, these memory devices have shown a high retention time of both hole and electron-trapping modes, reaching 2.8 × 10{sup 4} s at room temperature. The memory characteristics confirm that light illumination and electrical field can act as an independent programming/erasing operation method. This could be a fundamental step toward achieving high performance and stable operating nanoelectronic memory devices.

  16. Ferroelectric Thin Films Basic Properties and Device Physics for Memory Applications

    CERN Document Server

    Okuyama, Masanori

    2005-01-01

    Ferroelectric thin films continue to attract much attention due to their developing, diverse applications in memory devices, FeRAM, infrared sensors, piezoelectric sensors and actuators. This book, aimed at students, researchers and developers, gives detailed information about the basic properties of these materials and the associated device physics. All authors are acknowledged experts in the field.

  17. Size-dependent metal-insulator transition in platinum-dispersed silicon dioxide thin film: A candidate for future non-volatile memory

    Science.gov (United States)

    Chen, Albert B. K.

    Non-volatile random access memories (NVRAM) are promising data storage and processing devices. Various NVRAM, such as FeRAM and MRAM, have been studied in the past. But resistance switching random access memory (RRAM) has demonstrated the most potential for replacing flash memory in use today. In this dissertation, a novel RRAM material design that relies upon an electronic transition, rather than a phase change (as in chalcogenide Ovonic RRAM) or a structural change (such in oxide and halide filamentary RRAM), is investigated. Since the design is not limited to a single material but applicable to general combinations of metals and insulators, the goal of this study is to use a model material to delineate the intrinsic features of the electronic metal/insulator transition in random systems and to demonstrate their relevance to reliable memory storage and retrieval. We fabricated amorphous SiO2 thin films embedded with randomly dispersed Pt atoms. Macroscopically, this random material exhibits a percolation transition in electric conductivity similar to the one found in various insulator/metal granular materials. However, at Pt concentrations well below the bulk percolation limit, a distinct insulator to metal transition occurs in the thickness direction as the film thickness falls below electron's "diffusion" distance, which is the tunneling distance at 0K. The thickness-triggered metal- to-insulator transition (MIT) can be similarly triggered by other conditions: (a) a changing Pt concentration (a concentration-triggered MIT), (b) a changing voltage/polarity (voltage-triggered MIT), and (c) an UV irradiation (photon-triggered MIT). The resistance switching characteristics of this random material were further investigated in several device configurations under various test conditions. These include: materials for the top and bottom electrodes, fast pulsing, impedance spectroscopy, static stressing, retention, fatigue and temperature from 10K to 448K. The SiO2-Pt

  18. Memory devices with encapsulated Si nano-crystals: Realization and Characterization.

    NARCIS (Netherlands)

    Brunets, I.; Hemert, van T.; Boogaard, A.; Aarnink, A.A.I.; Kovalgin, A.Y.; Holleman, J.; Schmitz, J.

    2006-01-01

    In this work, the advanced non-volatile memory design based on silicon nano-crystals instead of conventional continuous floating gate was explored The multilayer Al/TiN/Al2O3/Si-nano-crystals/Al2O3/SiO2/Si(100) structure was realized. The functional layer stack (TiN/Al2O3/Si-nano-crystals/Al2O3) was

  19. Unipolar resistive switching in metal oxide/organic semiconductor non-volatile memories as a critical phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Bory, Benjamin F.; Meskers, Stefan C. J., E-mail: s.c.j.meskers@tue.nl [Molecular Materials and Nanosystems and Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Rocha, Paulo R. F. [Instituto de Telecomunicações, Av. Rovisco, Pais, 1, 1049-001 Lisboa, Portugal and Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany); Gomes, Henrique L. [Instituto de Telecomunicações, Av. Rovisco, Pais, 1, 1049-001 Lisboa, Portugal and Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Leeuw, Dago M. de [Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany)

    2015-11-28

    Diodes incorporating a bilayer of an organic semiconductor and a wide bandgap metal oxide can show unipolar, non-volatile memory behavior after electroforming. The prolonged bias voltage stress induces defects in the metal oxide with an areal density exceeding 10{sup 17 }m{sup −2}. We explain the electrical bistability by the coexistence of two thermodynamically stable phases at the interface between an organic semiconductor and metal oxide. One phase contains mainly ionized defects and has a low work function, while the other phase has mainly neutral defects and a high work function. In the diodes, domains of the phase with a low work function constitute current filaments. The phase composition and critical temperature are derived from a 2D Ising model as a function of chemical potential. The model predicts filamentary conduction exhibiting a negative differential resistance and nonvolatile memory behavior. The model is expected to be generally applicable to any bilayer system that shows unipolar resistive switching.

  20. Unipolar resistive switching in metal oxide/organic semiconductor non-volatile memories as a critical phenomenon

    Science.gov (United States)

    Bory, Benjamin F.; Rocha, Paulo R. F.; Gomes, Henrique L.; de Leeuw, Dago M.; Meskers, Stefan C. J.

    2015-11-01

    Diodes incorporating a bilayer of an organic semiconductor and a wide bandgap metal oxide can show unipolar, non-volatile memory behavior after electroforming. The prolonged bias voltage stress induces defects in the metal oxide with an areal density exceeding 1017 m-2. We explain the electrical bistability by the coexistence of two thermodynamically stable phases at the interface between an organic semiconductor and metal oxide. One phase contains mainly ionized defects and has a low work function, while the other phase has mainly neutral defects and a high work function. In the diodes, domains of the phase with a low work function constitute current filaments. The phase composition and critical temperature are derived from a 2D Ising model as a function of chemical potential. The model predicts filamentary conduction exhibiting a negative differential resistance and nonvolatile memory behavior. The model is expected to be generally applicable to any bilayer system that shows unipolar resistive switching.

  1. Analogue spin-orbit torque device for artificial-neural-network-based associative memory operation

    Science.gov (United States)

    Borders, William A.; Akima, Hisanao; Fukami, Shunsuke; Moriya, Satoshi; Kurihara, Shouta; Horio, Yoshihiko; Sato, Shigeo; Ohno, Hideo

    2017-01-01

    We demonstrate associative memory operations reminiscent of the brain using nonvolatile spintronics devices. Antiferromagnet-ferromagnet bilayer-based Hall devices, which show analogue-like spin-orbit torque switching under zero magnetic fields and behave as artificial synapses, are used. An artificial neural network is used to associate memorized patterns from their noisy versions. We develop a network consisting of a field-programmable gate array and 36 spin-orbit torque devices. An effect of learning on associative memory operations is successfully confirmed for several 3 × 3-block patterns. A discussion on the present approach for realizing spintronics-based artificial intelligence is given.

  2. Magnetic Resonance Flow Velocity and Temperature Mapping of a Shape Memory Polymer Foam Device

    Energy Technology Data Exchange (ETDEWEB)

    Small IV, W; Gjersing, E; Herberg, J L; Wilson, T S; Maitland, D J

    2008-10-29

    Interventional medical devices based on thermally responsive shape memory polymer (SMP) are under development to treat stroke victims. The goals of these catheter-delivered devices include re-establishing blood flow in occluded arteries and preventing aneurysm rupture. Because these devices alter the hemodynamics and dissipate thermal energy during the therapeutic procedure, a first step in the device development process is to investigate fluid velocity and temperature changes following device deployment. A laser-heated SMP foam device was deployed in a simplified in vitro vascular model. Magnetic resonance imaging (MRI) techniques were used to assess the fluid dynamics and thermal changes associated with device deployment. Spatial maps of the steady-state fluid velocity and temperature change inside and outside the laser-heated SMP foam device were acquired. Though non-physiological conditions were used in this initial study, the utility of MRI in the development of a thermally-activated SMP foam device has been demonstrated.

  3. Construction and Operation of Three-Dimensional Memory and Logic Molecular Devices and Circuits

    Science.gov (United States)

    2013-07-01

    decrease in measured current. “Traditional” NDR devices such as resonant tunnel diodes (RTD) or Gunn diodes , are commonly made of III-V...and memory devices in the form of resonant tunnel diodes (RTDs) used in the pre- CMOS era to construct digital circuits but with prohibitive fabrication...alternative material systems. Indeed, organic electronic devices such as field effect transistors, diodes , rectifiers and nanowires have been recently

  4. Role of the hippocampus in memory formation: restorative encoding memory integration neural device as a cognitive neural prosthesis.

    Science.gov (United States)

    Berger, Theodore; Song, Dong; Chan, Rosa; Shin, Dae; Marmarelis, Vasilis; Hampson, Robert; Sweatt, Andrew; Heck, Christi; Liu, Charles; Wills, Jack; Lacoss, Jeff; Granacki, John; Gerhardt, Greg; Deadwyler, Sam

    2012-01-01

    Remind, which stands for "restorative encoding memory integration neural device," is a Defense Advanced Research Projects Agency (DARPA)-sponsored program to construct the first-ever cognitive prosthesis to replace lost memory function and enhance the existing memory capacity in animals and, ultimately, in humans. Reaching this goal involves understanding something fundamental about the brain that has not been understood previously: how the brain internally codes memories. In developing a hippocampal prosthesis for the rat, we have been able to demonstrate a multiple-input, multiple- output (MIMO) nonlinear model that predicts in real time the spatiotemporal codes for specific memories required for correct performance on a standard learning/memory task, i.e., delayed-nonmatch-to-sample (DNMS) memory. The MIMO model has been tested successfully in a number of contexts; most notably, in animals with a pharmacologically disabled hippocampus, we were able to reinstate long-term memories necessary for correct DNMS behavior by substituting a MIMO model-predicted code, delivered by electrical stimulation to the hippocampus through an array of electrodes, resulting in spatiotemporal hippocampal activity that is normally generated endogenously. We also have shown that delivering the same model-predicted code to electrode-implanted control animals with a normally functioning hippocampus substantially enhances animals memory capacity above control levels. These results in rodents have formed the basis for extending the MIMO model to nonhuman primates; this is now underway as the last step of the REMIND program before developing a MIMO-based cognitive prosthesis for humans.

  5. Tuning the Electrical Memory Behavior from Nonvolatile to Volatile in Functional Copolyimides Bearing Varied Fluorene and Pyrene Moieties

    Science.gov (United States)

    Jia, Nanfang; Qi, Shengli; Tian, Guofeng; Wang, Xiaodong; Wu, Dezhen

    2017-04-01

    For producing polymer based electronics with good memory behavior, a series of functional copolyimides were designed and synthesized in this work by copolymerizing 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA) with (9,9'-bis(4-aminophenyl)fluorene) (BAPF) and N, N-bis(4-aminophenyl) aminopyrene (DAPAP) diamines. The synthesized copolyimides DSDA/(DAPAP/BAPF) were denoted as coPI-DAPAP x ( x = 100, 50, 20, 10, 5, 1, 0), where x% represents the molar fraction of the DAPAP unit in the diamines. Characterization results indicate that the coPI-DAPAP x exhibits tunable electrical switching behaviors from write once read many times (WORM, nonvolatile, coPI-DAPAP100, coPI-DAPAP50, coPI-DAPAP20, coPI-DAPAP10) to the static random access memory (SRAM, volatile, coPI-DAPAP5, coPI-DAPAP1) with the variation of the DAPAP content. Optical and electrochemical characterization show gradually decreasing highest occupied molecular orbital levels and enlarged energy gap with the decrease of the DAPAP moiety, suggesting decreasing charge-transfer effect in the copolyimides, which can account for the observed WORM-SRAM memory conversion. Meanwhile, the charge transfer process was elucidated by quantum chemical calculation at B3LYP/6-31G(d) theory level. This work shows the effect of electron donor content on the memory behavior of polymer electronic materials.

  6. NVL-C: Static Analysis Techniques for Efficient, Correct Programming of Non-Volatile Main Memory Systems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seyong [ORNL; Vetter, Jeffrey S [ORNL

    2016-01-01

    Computer architecture experts expect that non-volatile memory (NVM) hierarchies will play a more significant role in future systems including mobile, enterprise, and HPC architectures. With this expectation in mind, we present NVL-C: a novel programming system that facilitates the efficient and correct programming of NVM main memory systems. The NVL-C programming abstraction extends C with a small set of intuitive language features that target NVM main memory, and can be combined directly with traditional C memory model features for DRAM. We have designed these new features to enable compiler analyses and run-time checks that can improve performance and guard against a number of subtle programming errors, which, when left uncorrected, can corrupt NVM-stored data. Moreover, to enable recovery of data across application or system failures, these NVL-C features include a flexible directive for specifying NVM transactions. So that our implementation might be extended to other compiler front ends and languages, the majority of our compiler analyses are implemented in an extended version of LLVM's intermediate representation (LLVM IR). We evaluate NVL-C on a number of applications to show its flexibility, performance, and correctness.

  7. Tuning the Electrical Memory Behavior from Nonvolatile to Volatile in Functional Copolyimides Bearing Varied Fluorene and Pyrene Moieties

    Science.gov (United States)

    Jia, Nanfang; Qi, Shengli; Tian, Guofeng; Wang, Xiaodong; Wu, Dezhen

    2016-12-01

    For producing polymer based electronics with good memory behavior, a series of functional copolyimides were designed and synthesized in this work by copolymerizing 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA) with (9,9'-bis(4-aminophenyl)fluorene) (BAPF) and N,N-bis(4-aminophenyl) aminopyrene (DAPAP) diamines. The synthesized copolyimides DSDA/(DAPAP/BAPF) were denoted as coPI-DAPAPx (x = 100, 50, 20, 10, 5, 1, 0), where x% represents the molar fraction of the DAPAP unit in the diamines. Characterization results indicate that the coPI-DAPAPx exhibits tunable electrical switching behaviors from write once read many times (WORM, nonvolatile, coPI-DAPAP100, coPI-DAPAP50, coPI-DAPAP20, coPI-DAPAP10) to the static random access memory (SRAM, volatile, coPI-DAPAP5, coPI-DAPAP1) with the variation of the DAPAP content. Optical and electrochemical characterization show gradually decreasing highest occupied molecular orbital levels and enlarged energy gap with the decrease of the DAPAP moiety, suggesting decreasing charge-transfer effect in the copolyimides, which can account for the observed WORM-SRAM memory conversion. Meanwhile, the charge transfer process was elucidated by quantum chemical calculation at B3LYP/6-31G(d) theory level. This work shows the effect of electron donor content on the memory behavior of polymer electronic materials.

  8. Memory attacks on device-independent quantum cryptography.

    Science.gov (United States)

    Barrett, Jonathan; Colbeck, Roger; Kent, Adrian

    2013-01-01

    Device-independent quantum cryptographic schemes aim to guarantee security to users based only on the output statistics of any components used, and without the need to verify their internal functionality. Since this would protect users against untrustworthy or incompetent manufacturers, sabotage, or device degradation, this idea has excited much interest, and many device-independent schemes have been proposed. Here we identify a critical weakness of device-independent protocols that rely on public communication between secure laboratories. Untrusted devices may record their inputs and outputs and reveal information about them via publicly discussed outputs during later runs. Reusing devices thus compromises the security of a protocol and risks leaking secret data. Possible defenses include securely destroying or isolating used devices. However, these are costly and often impractical. We propose other more practical partial defenses as well as a new protocol structure for device-independent quantum key distribution that aims to achieve composable security in the case of two parties using a small number of devices to repeatedly share keys with each other (and no other party).

  9. Charge Carrier Transport Mechanism Based on Stable Low Voltage Organic Bistable Memory Device.

    Science.gov (United States)

    Ramana, V V; Moodley, M K; Kumar, A B V Kiran; Kannan, V

    2015-05-01

    A solution processed two terminal organic bistable memory device was fabricated utilizing films of polymethyl methacrylate PMMA/ZnO/PMMA on top of ITO coated glass. Electrical characterization of the device structure showed that the two terminal device exhibited favorable switching characteristics with an ON/OFF ratio greater than 1 x 10(4) when the voltage was swept between - 2 V and +3 V. The device maintained its state after removal of the bias voltage. The device did not show degradation after a 1-h retention test at 120 degrees C. The memory functionality was consistent even after fifty cycles of operation. The charge transport switching mechanism is discussed on the basis of carrier transport mechanism and our analysis of the data shows that the charge carrier trans- port mechanism of the device during the writing process can be explained by thermionic emission (TE) and space-charge-limited-current (SCLC) mechanism models while erasing process could be explained by the FN tunneling mechanism. This demonstration provides a class of memory devices with the potential for low-cost, low-power consumption applications, such as a digital memory cell.

  10. Shape-memory polymer foam device for treating aneurysms

    Science.gov (United States)

    Ortega, Jason M.; Benett, William J.; Small, Ward; Wilson, Thomas S.; Maitland, Duncan J; Hartman, Jonathan

    2017-05-30

    A system for treating an aneurysm in a blood vessel or vein, wherein the aneurysm has a dome, an interior, and a neck. The system includes a shape memory polymer foam in the interior of the aneurysm between the dome and the neck. The shape memory polymer foam has pores that include a first multiplicity of pores having a first pore size and a second multiplicity of pores having a second pore size. The second pore size is larger than said first pore size. The first multiplicity of pores are located in the neck of the aneurysm. The second multiplicity of pores are located in the dome of the aneurysm.

  11. Computing with volatile memristors: an application of non-pinched hysteresis

    Science.gov (United States)

    Pershin, Y. V.; Shevchenko, S. N.

    2017-02-01

    The possibility of in-memory computing with volatile memristive devices, namely, memristors requiring a power source to sustain their memory, is demonstrated theoretically. We have adopted a hysteretic graphene-based field emission structure as a prototype of a volatile memristor, which is characterized by a non-pinched hysteresis loop. A memristive model of the structure is developed and used to simulate a polymorphic circuit implementing stateful logic gates, such as the material implication. Specific regions of parameter space realizing useful logic functions are identified. Our results are applicable to other realizations of volatile memory devices, such as certain NEMS switches.

  12. A Radiation-Tolerant, Low-Power Non-Volatile Memory Based on Silicon Nanocrystal Quantum Dots

    Science.gov (United States)

    Bell, L. D.; Boer, E. A.; Ostraat, M. L.; Brongersma, M. L.; Flagan, R. C.; Atwater, H. A.; deBlauwe, J.; Green, M. L.

    2001-01-01

    Nanocrystal nonvolatile floating-gate memories are a good candidate for space applications - initial results suggest they are fast, more reliable and consume less power than conventional floating gate memories. In the nanocrystal based NVM device, charge is not stored on a continuous polysilicon layer (so-called floating gate), but instead on a layer of discrete nanocrystals. Charge injection and storage in dense arrays of silicon nanocrystals in SiO2 is a critical aspect of the performance of potential nanocrystal flash memory structures. The ultimate goal for this class of devices is few- or single-electron storage in a small number of nanocrystal elements. In addition, the nanocrystal layer fabrication technique should be simple, 8-inch wafer compatible and well controlled in program/erase threshold voltage swing was seen during 100,000 program and erase cycles. Additional near-term goals for this project include extensive testing for radiation hardness and the development of artificial layered tunnel barrier heterostructures which have the potential for large speed enhancements for read/write of nanocrystal memory elements, compared with conventional flash devices. Additional information is contained in the original extended abstract.

  13. A novel 2-T structure memory device using a Si nanodot for embedded application

    Institute of Scientific and Technical Information of China (English)

    Yang Xiaonan; Wang Yong; Zhang Manhong; Huo Zongliang; Liu Jing; Zhang Bo; Liu Ming

    2011-01-01

    Performance and reliability ofa 2 transistor Si nanocrystal nonvolatile memory(NVM)are investigated.A good performance of the memory cell has been achieved,including a fast program/erase(P/E)speed under low voltages,an excellent data retention(maintaining for 10 years)and good endurance with a less threshold voltage shift of less than 10% after 104 P/E cycles.The data show that the device has strong potential for future embedded NVM applications.

  14. High-performance nonvolatile organic transistor memory devices using the electrets of semiconducting blends.

    Science.gov (United States)

    Chiu, Yu-Cheng; Chen, Tzu-Ying; Chen, Yougen; Satoh, Toshifumi; Kakuchi, Toyoji; Chen, Wen-Chang

    2014-08-13

    Organic nonvolatile transistor memory devices of the n-type semiconductor N,N'-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI) were prepared using various electrets (i.e., three-armed star-shaped poly[4-(diphenylamino)benzyl methacrylate] (N(PTPMA)3) and its blends with 6,6-phenyl-C61-butyric acid methyl ester (PCBM), 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pen) or ferrocene). In the device using the PCBM:N(PTPMA)3 blend electret, it changed its memory feature from a write-once-read-many (WORM) type to a flash type as the PCBM content increased and could be operated repeatedly based on a tunneling process. The large shifts on the reversible transfer curves and the hysteresis after implementing a gate bias indicated the considerable charge storage in the electret layer. On the other hand, the memory characteristics showed a flash type and a WORM characteristic, respectively, using the donor/donor electrets TIPS-pen:N(PTPMA)3 and ferrocene:N(PTPMA)3. The variation on the memory characteristics was attributed to the difference of energy barrier at the interface when different types of electret materials were employed. All the studied memory devices exhibited a long retention over 10(4) s with a highly stable read-out current. In addition, the afore-discussed memory devices by inserting another electret layer of poly(methacrylic acid) (PMAA) between the BPE-PTCDI layer and the semiconducting blend layer enhanced the write-read-erase-read (WRER) operation cycle as high as 200 times. This study suggested that the energy level and charge transfer in the blend electret had a significant effect on tuning the characteristics of nonvolatile transistor memory devices.

  15. Adaptive repair device concept with shape memory polymer

    Science.gov (United States)

    Zhao, Wei; Liu, Liwu; Lan, Xin; Su, Bo; Leng, Jinsong; Liu, Yanju

    2017-02-01

    Shape memory polymer (SMP) is a new kind of intelligent polymer, which can be activated by an external stimulus to change and subsequently recover its original shape. Due to this shape memory effect, SMP can be used in a wide range of engineering and biomedical applications. This paper details an application of SMP on manufacturing of a fracture fixation. The basic properties were characterized by dynamic mechanical analysis, and the stress relaxation and fatigue were established. An SMP-based fracture fixator was designed, analyzed, and optimized. Finally, the fixator was fabricated and the fixed effects were verified by experiment in vitro. The performance of the SMP-based fixator was excellent and proved to be a potential replacement for the traditional fracture fixator.

  16. The effectiveness of music as a mnemonic device on recognition memory for people with multiple sclerosis.

    Science.gov (United States)

    Moore, Kimberly Sena; Peterson, David A; O'Shea, Geoffrey; McIntosh, Gerald C; Thaut, Michael H

    2008-01-01

    Research shows that people with multiple sclerosis exhibit learning and memory difficulties and that music can be used successfully as a mnemonic device to aid in learning and memory. However, there is currently no research investigating the effectiveness of music mnemonics as a compensatory learning strategy for people with multiple sclerosis. Participants with clinically definitive multiple sclerosis (N = 38) were given a verbal learning and memory test. Results from a recognition memory task were analyzed that compared learning through music (n = 20) versus learning through speech (n = 18). Preliminary baseline neuropsychological data were collected that measured executive functioning skills, learning and memory abilities, sustained attention, and level of disability. An independent samples t test showed no significant difference between groups on baseline neuropsychological functioning or on recognition task measures. Correlation analyses suggest that music mnemonics may facilitate learning for people who are less impaired by the disease. Implications for future research are discussed.

  17. Nonvolatile multilevel data storage memory device from controlled ambipolar charge trapping mechanism

    Science.gov (United States)

    Zhou, Ye; Han, Su-Ting; Sonar, Prashant; Roy, V. A. L.

    2013-07-01

    The capability of storing multi-bit information is one of the most important challenges in memory technologies. An ambipolar polymer which intrinsically has the ability to transport electrons and holes as a semiconducting layer provides an opportunity for the charge trapping layer to trap both electrons and holes efficiently. Here, we achieved large memory window and distinct multilevel data storage by utilizing the phenomena of ambipolar charge trapping mechanism. As fabricated flexible memory devices display five well-defined data levels with good endurance and retention properties showing potential application in printed electronics.

  18. The Effect of Long Memory in Volatility on Stock Market Fluctuations

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper; Nielsen, Morten Ørregaard

    on returns. Asset pricing theory imposes testable cross- equation restrictions on the system that are not rejected in our preferred specifications, which include a strong financial leverage effect. We show that the impact of volatility shocks on stock prices is small and short-lived, in spite of a positive...

  19. The Effect of Long Memory in Volatility on Stock Market Fluctuations

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper; Nielsen, Morten Ørregaard

    on returns. Asset pricing theory imposes testable cross-equation restrictions on the system that are not rejected in our preferred specifications, which include a strong financial leverage effect. We show that the impact of volatility shocks on stock prices is small and short-lived, in spite of a positive...

  20. Stochastic model of financial markets reproducing scaling and memory in volatility return intervals

    Science.gov (United States)

    Gontis, V.; Havlin, S.; Kononovicius, A.; Podobnik, B.; Stanley, H. E.

    2016-11-01

    We investigate the volatility return intervals in the NYSE and FOREX markets. We explain previous empirical findings using a model based on the interacting agent hypothesis instead of the widely-used efficient market hypothesis. We derive macroscopic equations based on the microscopic herding interactions of agents and find that they are able to reproduce various stylized facts of different markets and different assets with the same set of model parameters. We show that the power-law properties and the scaling of return intervals and other financial variables have a similar origin and could be a result of a general class of non-linear stochastic differential equations derived from a master equation of an agent system that is coupled by herding interactions. Specifically, we find that this approach enables us to recover the volatility return interval statistics as well as volatility probability and spectral densities for the NYSE and FOREX markets, for different assets, and for different time-scales. We find also that the historical S&P500 monthly series exhibits the same volatility return interval properties recovered by our proposed model. Our statistical results suggest that human herding is so strong that it persists even when other evolving fluctuations perturbate the financial system.

  1. Resistive Switching of Individual Dislocations in Insulating Perovskites -- A Potential Route Towards Nanoscale Non-Volatile Memories.

    Science.gov (United States)

    Szot, Krzystof; Speier, Wolfgang; Bihlmayer, Gustav; Waser, Rainer

    2006-03-01

    dislocations. Switching in our case corresponds then to an electrochemical ``closing'' or ``opening'' of the single dislocation in the uppermost portion of the network. Our results show that the switching behaviour in single-crystalline SrTiO3 is an inherent property of the material and can be easily activated by external stimuli. Due to the availability of dislocation densities up to 10^12 cm-2 in single crystals and thin film, one can even envisage to approach the Tbit regime, as long as the dislocations can be successfully arranged into registered superstructures. In summary, evidence is given that the electrical conductance of individual dislocations in a prototype perovskite, SrTiO3, can be switched between a low and a high conducting state by the application of an electrical field. We demonstrate on the basis of ab initio calculations and measurements with a scanning probe microscope SPM that the modulation of the electrical properties is related to the induced change in oxygen stoichiometry and the self-doping capability with a local insulator- metal transition along the core of the dislocations. A model is presented based on a three-dimensional network of such a filamentary structure to analyze the bi-stable resistive switching in the macroscopic metal-insulator-metal (MIM) structure. Our results show that electrically addressing individual dislocations in single crystals as well as epitaxial thin films provides a dynamic range for switching between low and high conducting states which covers several orders of magnitude in resistance and can be of technological interest for the application in Tbit non-volatile memory devices..

  2. Flexible and twistable non-volatile memory cell array with all-organic one diode-one resistor architecture.

    Science.gov (United States)

    Ji, Yongsung; Zeigler, David F; Lee, Dong Su; Choi, Hyejung; Jen, Alex K-Y; Ko, Heung Cho; Kim, Tae-Wook

    2013-01-01

    Flexible organic memory devices are one of the integral components for future flexible organic electronics. However, high-density all-organic memory cell arrays on malleable substrates without cross-talk have not been demonstrated because of difficulties in their fabrication and relatively poor performances to date. Here we demonstrate the first flexible all-organic 64-bit memory cell array possessing one diode-one resistor architectures. Our all-organic one diode-one resistor cell exhibits excellent rewritable switching characteristics, even during and after harsh physical stresses. The write-read-erase-read output sequence of the cells perfectly correspond to the external pulse signal regardless of substrate deformation. The one diode-one resistor cell array is clearly addressed at the specified cells and encoded letters based on the standard ASCII character code. Our study on integrated organic memory cell arrays suggests that the all-organic one diode-one resistor cell architecture is suitable for high-density flexible organic memory applications in the future.

  3. Memory Analysis of the KBeast Linux Rootkit: Investigating Publicly Available Linux Rootkit Using the Volatility Memory Analysis Framework

    Science.gov (United States)

    2015-06-01

    on his computer system or network. Use of these tools and the analysis of virulent software always carry some inherent risk that must be securely...study of operating system internals and software reverse engineering techniques. Instead, this work should be considered as a guide to using the...employed throughout this text for the purpose of simplification . DRDC-RDDC-2015-R064 xi Availability of Linux memory images and profiles

  4. Compact modeling of CRS devices based on ECM cells for memory, logic and neuromorphic applications

    Science.gov (United States)

    Linn, E.; Menzel, S.; Ferch, S.; Waser, R.

    2013-09-01

    Dynamic physics-based models of resistive switching devices are of great interest for the realization of complex circuits required for memory, logic and neuromorphic applications. Here, we apply such a model of an electrochemical metallization (ECM) cell to complementary resistive switches (CRSs), which are favorable devices to realize ultra-dense passive crossbar arrays. Since a CRS consists of two resistive switching devices, it is straightforward to apply the dynamic ECM model for CRS simulation with MATLAB and SPICE, enabling study of the device behavior in terms of sweep rate and series resistance variations. Furthermore, typical memory access operations as well as basic implication logic operations can be analyzed, revealing requirements for proper spike and level read operations. This basic understanding facilitates applications of massively parallel computing paradigms required for neuromorphic applications.

  5. Bipolar resistive switching characteristics in tantalum nitride-based resistive random access memory devices

    Science.gov (United States)

    Kim, Myung Ju; Jeon, Dong Su; Park, Ju Hyun; Kim, Tae Geun

    2015-05-01

    This paper reports the bipolar resistive switching characteristics of TaNx-based resistive random access memory (ReRAM). The conduction mechanism is explained by formation and rupture of conductive filaments caused by migration of nitrogen ions and vacancies; this mechanism is in good agreement with either Ohmic conduction or the Poole-Frenkel emission model. The devices exhibit that the reset voltage varies from -0.82 V to -0.62 V, whereas the set voltage ranges from 1.01 V to 1.30 V for 120 DC sweep cycles. In terms of reliability, the devices exhibit good retention (>105 s) and pulse-switching endurance (>106 cycles) properties. These results indicate that TaNx-based ReRAM devices have a potential for future nonvolatile memory devices.

  6. Bipolar resistive switching characteristics in tantalum nitride-based resistive random access memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myung Ju; Jeon, Dong Su; Park, Ju Hyun; Kim, Tae Geun, E-mail: tgkim1@korea.ac.kr [School of Electrical Engineering, Anam-dong 5ga, Sungbuk-gu, Seoul 136-701 (Korea, Republic of)

    2015-05-18

    This paper reports the bipolar resistive switching characteristics of TaN{sub x}-based resistive random access memory (ReRAM). The conduction mechanism is explained by formation and rupture of conductive filaments caused by migration of nitrogen ions and vacancies; this mechanism is in good agreement with either Ohmic conduction or the Poole-Frenkel emission model. The devices exhibit that the reset voltage varies from −0.82 V to −0.62 V, whereas the set voltage ranges from 1.01 V to 1.30 V for 120 DC sweep cycles. In terms of reliability, the devices exhibit good retention (>10{sup 5 }s) and pulse-switching endurance (>10{sup 6} cycles) properties. These results indicate that TaN{sub x}-based ReRAM devices have a potential for future nonvolatile memory devices.

  7. Interface-engineered templates for molecular spin memory devices

    NARCIS (Netherlands)

    Raman, Karthik V.; Kamerbeek, Alexander M.; Mukherjee, Arup; Atodiresei, Nicolae; Sen, Tamal K.; Lazic, Predrag; Caciuc, Vasile; Michel, Reent; Stalke, Dietmar; Mandal, Swadhin K.; Bluegel, Stefan; Muenzenberg, Markus; Moodera, Jagadeesh S.

    2013-01-01

    The use of molecular spin state as a quantum of information for storage, sensing and computing has generated considerable interest in the context of next-generation data storage and communication devices(1,2), opening avenues for developing multifunctional molecular spintronics(3). Such ideas have

  8. Effects of device size and material on the bending performance of resistive-switching memory devices fabricated on flexible substrates

    Science.gov (United States)

    Lee, Won-Ho; Yoon, Sung-Min

    2017-05-01

    The resistive change memory (RCM) devices using amorphous In-Ga-Zn-O (IGZO) and microcrystalline Al-doped ZnO (AZO) thin films were fabricated on plastic substrates and characterized for flexible electronic applications. The device cell sizes were varied to 25 × 25, 50 × 50, 100 × 100, and 200 × 200 μm2 to examine the effects of cell size on the resistive-switching (RS) behaviors at a flat state and under bending conditions. First, it was found that the high-resistance state programmed currents markedly increased with the increase in the cell size. Second, while the AZO RCM devices did not exhibit RESET operations at a curvature radius smaller than 8.0 mm, the IGZO RCM devices showed sound RS behaviors even at a curvature radius of 4.5 mm. Third, for the IGZO RCM devices with the cell size bigger than 100 × 100 μm2, the RESET operation could not be performed at a curvature radius smaller than 6.5 mm. Thus, it was elucidated that the RS characteristics of the flexible RCM devices using oxide semiconductor thin films were closely related to the types of RS materials and the cell size of the device.

  9. Configurable Resistive Switching between Memory and Threshold Characteristics for Protein-Based Devices

    KAUST Repository

    Wang, Hong

    2015-05-01

    The employ of natural biomaterials as the basic building blocks of electronic devices is of growing interest for biocompatible and green electronics. Here, resistive switching (RS) devices based on naturally silk protein with configurable functionality are demonstrated. The RS type of the devices can be effectively and exactly controlled by controlling the compliance current in the set process. Memory RS can be triggered by a higher compliance current, while threshold RS can be triggered by a lower compliance current. Furthermore, two types of memory devices, working in random access and WORM modes, can be achieved with the RS effect. The results suggest that silk protein possesses the potential for sustainable electronics and data storage. In addition, this finding would provide important guidelines for the performance optimization of biomaterials based memory devices and the study of the underlying mechanism behind the RS effect arising from biomaterials. Resistive switching (RS) devices with configurable functionality based on protein are successfully achieved. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Spatially resolved Raman spectroelectrochemistry of solid-state polythiophene/viologen memory devices.

    Science.gov (United States)

    Kumar, Rajesh; Pillai, Rajesh G; Pekas, Nikola; Wu, Yiliang; McCreery, Richard L

    2012-09-12

    A three terminal molecular memory device was monitored with in situ Raman spectroscopy during bias-induced switching between two metastable states having different conductivity. The device structure is similar to that of a polythiophene field effect transistor, but ethylviologen perchlorate was added to provide a redox counter-reaction to accompany polythiophene redox reactions. The conductivity of the polythiophene layer was reversibly switched between high and low conductance states with a "write/erase" (W/E) bias, while a separate readout circuit monitored the polymer conductance. Raman spectroscopy revealed reversible polythiophene oxidation to its polaron form accompanied by a one-electron viologen reduction. "Write", "read", and "erase" operations were repeatable, with only minor degradation of response after 200 W/E cycles. The devices exhibited switching immediately after fabrication and did not require an "electroforming" step required in many types of memory devices. Spatially resolved Raman spectroscopy revealed polaron formation throughout the polymer layer, even away from the electrodes in the channel and drain regions, indicating that thiophene oxidation "propagates" by growth of the conducting polaron form away from the source electrode. The results definitively demonstrate concurrent redox reactions of both polythiophene and viologen in solid-state devices and correlate such reactions with device conductivity. The mechanism deduced from spectroscopic and electronic monitoring should guide significant improvements in memory performance.

  11. Phase change memory

    CERN Document Server

    Qureshi, Moinuddin K

    2011-01-01

    As conventional memory technologies such as DRAM and Flash run into scaling challenges, architects and system designers are forced to look at alternative technologies for building future computer systems. This synthesis lecture begins by listing the requirements for a next generation memory technology and briefly surveys the landscape of novel non-volatile memories. Among these, Phase Change Memory (PCM) is emerging as a leading contender, and the authors discuss the material, device, and circuit advances underlying this exciting technology. The lecture then describes architectural solutions t

  12. Exploration of Uninitialized Configuration Memory Space for Intrinsic Identification of Xilinx Virtex-5 FPGA Devices

    Directory of Open Access Journals (Sweden)

    Oliver Sander

    2012-01-01

    Full Text Available SRAM-based fingerprinting uses deviations in power-up behaviour caused by the CMOS fabrication process to identify distinct devices. This method is a promising technique for unique identification of physical devices. In the case of SRAM-based hardware reconfigurable devices such as FPGAs, the integrated SRAM cells are often initialized automatically at power-up, sweeping potential identification data. We demonstrate an approach to utilize unused parts of configuration memory space for device identification. Based on a total of over 200,000 measurements on nine Xilinx Virtex-5 FPGAs, we show that the retrieved values have promising properties with respect to consistency on one device, variety between different devices, and stability considering temperature variation and aging.

  13. Early exposure to volatile anesthetics impairs long-term associative learning and recognition memory.

    Directory of Open Access Journals (Sweden)

    Bradley H Lee

    Full Text Available BACKGROUND: Anesthetic exposure early in life affects neural development and long-term cognitive function, but our understanding of the types of memory that are altered is incomplete. Specific cognitive tests in rodents that isolate different memory processes provide a useful approach for gaining insight into this issue. METHODS: Postnatal day 7 (P7 rats were exposed to either desflurane or isoflurane at 1 Minimum Alveolar Concentration for 4 h. Acute neuronal death was assessed 12 h later in the thalamus, CA1-3 regions of hippocampus, and dentate gyrus. In separate behavioral experiments, beginning at P48, subjects were evaluated in a series of object recognition tests relying on associative learning, as well as social recognition. RESULTS: Exposure to either anesthetic led to a significant increase in neuroapoptosis in each brain region. The extent of neuronal death did not differ between groups. Subjects were unaffected in simple tasks of novel object and object-location recognition. However, anesthetized animals from both groups were impaired in allocentric object-location memory and a more complex task requiring subjects to associate an object with its location and contextual setting. Isoflurane exposure led to additional impairment in object-context association and social memory. CONCLUSION: Isoflurane and desflurane exposure during development result in deficits in tasks relying on associative learning and recognition memory. Isoflurane may potentially cause worse impairment than desflurane.

  14. Nanochip: a MEMS-Based Ultra-High Data Density Memory Device

    Directory of Open Access Journals (Sweden)

    Nickolai BELOV

    2009-10-01

    Full Text Available he paper provides an overview of successful development of MEMS micro-mover with large range of motion and an array of cantilevers with sharp tips (read-write heads for a probe storage device. Approaches used for integration of memory material into the MEMS process and integration of MEMS cantilever process with CMOS are briefly discussed.

  15. Realization of transient memory-loss with NiO-based resistive switching device

    Science.gov (United States)

    Hu, S. G.; Liu, Y.; Chen, T. P.; Liu, Z.; Yu, Q.; Deng, L. J.; Yin, Y.; Hosaka, Sumio

    2012-11-01

    A resistive switching device based on a nickel-rich nickel oxide thin film, which exhibits inherent learning and memory-loss abilities, is reported in this work. The conductance of the device gradually increases and finally saturates with the number of voltage pulses (or voltage sweepings), which is analogous to the behavior of the short-term and long-term memory in the human brain. Furthermore, the number of the voltage pulses (or sweeping cycles) required to achieve a given conductance state increases with the interval between two consecutive voltage pulses (or sweeping cycles), which is attributed to the heat diffusion in the material of the conductive filaments formed in the nickel oxide thin film. The phenomenon resembles the behavior of the human brain, i.e., forgetting starts immediately after an impression, a larger interval of the impressions leads to more memory loss, thus the memorization needs more impressions to enhance.

  16. SEMICONDUCTOR DEVICES: Reducing the influence of STI on SONOS memory through optimizing added boron implantation technology

    Science.gov (United States)

    Yue, Xu; Feng, Yan; Zhiguo, Li; Fan, Yang; Yonggang, Wang; Jianguang, Chang

    2010-09-01

    The influence of shallow trench isolation (STI) on a 90 nm polysilicon-oxide-nitride-oxide-silicon structure non-volatile memory has been studied based on experiments. It has been found that the performance of edge memory cells adjacent to STI deteriorates remarkably. The compressive stress and boron segregation induced by STI are thought to be the main causes of this problem. In order to mitigate the STI impact, an added boron implantation in the STI region is developed as a new solution. Four kinds of boron implantation experiments have been implemented to evaluate the impact of STI on edge cells, respectively. The experimental results show that the performance of edge cells can be greatly improved through optimizing added boron implantation technology.

  17. Fabrication and properties of nanoscale multiferroic heterostructures for application in magneto-electric random access memory (MERAM) devices

    Science.gov (United States)

    Kim, Gunwoo

    Magnetoelectric random access memory (MERAM) has emerged as a promising new class of non-volatile solid-state memory device. It offers nondestructive reading along with low power consumption during the write operation. A common implementation of MERAM involves use of multiferroic tunneling junctions (MFTJs), which besides offering non-volatility are both electrically and magnetically tunable. Fundamentally, a MFTJ consists of a heterostructure of an ultrathin multiferroic or ferroelectric material as the active tunneling barrier sandwiched between ferromagnetic electrodes. Thereby, the MFTJ exhibits both tunnel electroresistance (TER) and tunnel magnetoresistance (TMR) effects with application of an electric and magnetic field, respectively. In this thesis work, we have developed two-dimensional (2D) thin-film multiferroic heterostructure METJ prototypes consisting of ultrathin ferroelectric BaTiO3 (BTO) layer and a conducting ferromagnetic La0.67Sr 0.33MnO3 (LSMO) electrode. The heteroepitaxial films are grown using the pulsed laser deposition (PLD) technique. This oxide heterostructure offers the opportunity to study the nano-scale details of the tunnel electroresistance (TER) effect using scanning probe microscopy techniques. We performed the measurements using the MFP-3D (Asylum Research) scanning probe microscope. The ultrathin BTO films (1.2-2.0 nm) grown on LSMO electrodes display both ferro- and piezo-electric properties and exhibit large tunnel resistance effect. We have explored the growth and properties of one-dimensional (1D) heterostructures, referred to as multiferoric nanowire (NW) heterostructures. The ferromagnetic/ferroelectric composite heterostructures are grown as sheath layers using PLD on lattice-matched template NWs, e.g. MgO, that are deposited by chemical vapor deposition utilizing the vapor-liquid-solid (VLS) mechanism. The one-dimensional geometry can substantially overcome the clamping effect of the substrate present in two

  18. Using a source-receptor approach to characterize the volatile organic compounds from control device exhaust in a science park.

    Science.gov (United States)

    Chen, Chi-Fan; Liang, Jeng-Jong

    2013-03-01

    The science parks have helped shape Taiwan as a high-tech island with a good reputation worldwide. But some complaints on air pollution from the science parks have recently risen. To better understand the environmental effects of volatile organic compounds (VOCs) emitted from various high-tech factories in a science park, this study uses a source-receptor approach to characterize the environmental effects of VOCs from control device exhaust in Taichung Science Park. The chemical mass balance model (CMB8.2) of field measurements of 30 stacks and ambient air at nine sites was used to identify the source and relative contribution of ambient VOCs. The exhaust gas of various pollution control devices was also sampled by drawing a stream of the gases from the exhaust duct at its sampling port. The VOC source profile of each control device exhaust was determined using a database of noncharacteristic compounds. Monthly ambient concentrations of 167 VOCs were divided into monsoon datasets to investigate the effect of monsoon conditions on the emission of VOCs in the science park. This study also suggests a method for determining the optimum source profile in source-receptor modeling, and identifies and analyzes the sources of ambient VOCs at nine sites during southwest and northeast monsoons. Results show a direct relationship between the relative contribution of each source and its control device efficiency. The proposed source-receptor approach can characterize the environmental effect of air pollutants from various factories and successfully assess the efficiency of various control devices.

  19. A bio-inspired memory device based on interfacing Physarum polycephalum with an organic semiconductor

    Directory of Open Access Journals (Sweden)

    Agostino Romeo

    2015-01-01

    Full Text Available The development of devices able to detect and record ion fluxes is a crucial point in order to understand the mechanisms that regulate communication and life of organisms. Here, we take advantage of the combined electronic and ionic conduction properties of a conducting polymer to develop a hybrid organic/living device with a three-terminal configuration, using the Physarum polycephalum Cell (PPC slime mould as a living bio-electrolyte. An over-oxidation process induces a conductivity switch in the polymer, due to the ionic flux taking place at the PPC/polymer interface. This behaviour endows a current-depending memory effect to the device.

  20. A bio-inspired memory device based on interfacing Physarum polycephalum with an organic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Romeo, Agostino; Dimonte, Alice; Tarabella, Giuseppe; D’Angelo, Pasquale, E-mail: dangelo@imem.cnr.it, E-mail: iannotta@imem.cnr.it; Erokhin, Victor; Iannotta, Salvatore, E-mail: dangelo@imem.cnr.it, E-mail: iannotta@imem.cnr.it [IMEM-CNR, Institute of Materials for Electronics and Magnetism-National Research Council, Parma 43124 (Italy)

    2015-01-01

    The development of devices able to detect and record ion fluxes is a crucial point in order to understand the mechanisms that regulate communication and life of organisms. Here, we take advantage of the combined electronic and ionic conduction properties of a conducting polymer to develop a hybrid organic/living device with a three-terminal configuration, using the Physarum polycephalum Cell (PPC) slime mould as a living bio-electrolyte. An over-oxidation process induces a conductivity switch in the polymer, due to the ionic flux taking place at the PPC/polymer interface. This behaviour endows a current-depending memory effect to the device.

  1. Memory effects in a Al/Ti:HfO2/CuPc metal-oxide-semiconductor device

    Science.gov (United States)

    Tripathi, Udbhav; Kaur, Ramneek

    2016-05-01

    Metal oxide semiconductor structured organic memory device has been successfully fabricated. Ti doped hafnium oxide (Ti:HfO2) nanoparticles has been fabricated by precipitation method and further calcinated at 800 °C. Copper phthalocyanine, a hole transporting material has been utilized as an organic semiconductor. The electrical properties of the fabricated device have been studied by measuring the current-voltage and capacitance-voltage characteristics. The amount of charge stored in the nanoparticles has been calculated by using flat band condition. This simple approach for fabricating MOS memory device has opens up opportunities for the development of next generation memory devices.

  2. Memory effects in a Al/Ti:HfO{sub 2}/CuPc metal-oxide-semiconductor device

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, Udbhav, E-mail: udbhav1781996@gmail.com; Kaur, Ramneek [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India)

    2016-05-23

    Metal oxide semiconductor structured organic memory device has been successfully fabricated. Ti doped hafnium oxide (Ti:HfO{sub 2}) nanoparticles has been fabricated by precipitation method and further calcinated at 800 °C. Copper phthalocyanine, a hole transporting material has been utilized as an organic semiconductor. The electrical properties of the fabricated device have been studied by measuring the current-voltage and capacitance-voltage characteristics. The amount of charge stored in the nanoparticles has been calculated by using flat band condition. This simple approach for fabricating MOS memory device has opens up opportunities for the development of next generation memory devices.

  3. Negative effect of Au nanoparticles on an IGZO TFT-based nonvolatile memory device

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Myunghoon; Yoo, Gwangwe; Lee, Jongtaek; Jeong, Seokwon; Roh, Yonghan; Park, Jinhong; Kwon, Namyong [Sungkyunkwan University, Suwon (Korea, Republic of); Jung, Wooshik [Stanford University, Stanford, CA (United States)

    2014-02-15

    In this letter, the electrical characteristics of nonvolatile memory devices based on back gate type indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) are investigated in terms of the Au nanoparticles (NPs) employed in the floating gate-stack of the device. The size of the Au NPs is controlled using a by 500 .deg. C annealing process after the Au thin-film deposition. The size and the roughness of the Au NPs were observed by using scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. In order to analyze the electrical properties according to Au NP size, we measured the current-voltage (I{sub D}-V{sub G}) characteristics of the nonvolatile memory devices fabricated without Au NPs and with Au NPs of various sizes. The size of the Au NP increased, so did the surface roughness of the gate. This resulted in increased carrier scattering, which subsequently degraded the on-current of the memory device. In addition, inter-diffusion between the Au and the α-IGZO through the non-uniform Al{sub 2}O{sub 3} tunneling layer seemed to further degrade the device performance.

  4. Anomalous Threshold Voltage Variability of Nitride Based Charge Storage Nonvolatile Memory Devices

    Directory of Open Access Journals (Sweden)

    Meng Chuan Lee

    2013-01-01

    Full Text Available Conventional technology scaling is implemented to meet the insatiable demand of high memory density and low cost per bit of charge storage nonvolatile memory (NVM devices. In this study, effect of technology scaling to anomalous threshold voltage ( variability is investigated thoroughly on postcycled and baked nitride based charge storage NVM devices. After long annealing bake of high temperature, cell’s variability of each subsequent bake increases within stable distribution and found exacerbate by technology scaling. Apparent activation energy of this anomalous variability was derived through Arrhenius plots. Apparent activation energy (Eaa of this anomalous variability is 0.67 eV at sub-40 nm devices which is a reduction of approximately 2 times from 110 nm devices. Technology scaling clearly aggravates this anomalous variability, and this poses reliability challenges to applications that demand strict control, for example, reference cells that govern fundamental program, erase, and verify operations of NVM devices. Based on critical evidence, this anomalous variability is attributed to lateral displacement of trapped charges in nitride storage layer. Reliability implications of this study are elucidated. Moreover, potential mitigation methods are proposed to complement technology scaling to prolong the front-runner role of nitride based charge storage NVM in semiconductor flash memory market.

  5. Development of a self-contained device for rapid detection of volatile impurities in the oil system of a turbine

    Science.gov (United States)

    Starostin, A. A.; Shangin, V. V.; Bukhman, V. G.; Volosnikov, D. V.; Skripov, P. V.

    2016-08-01

    The research is devoted to development of a self-contained device for rapid detection of volatile impurities in the oil system of a turbine and testing it using the operating equipment. The device consists of a remote sensor, whose sensitive element is a 3-5-mm long wire probe 20 microns in diameter, and a measurement unit that comprises a microcontroller with a set of peripherals. The design of the device enables automation of the measurement procedure with a minimum number of preset settings and real-time output of information to the operator console. The software of the device provides two-stage pulse heating of the wire probe and a resistance temperature detector. The two-stage mode proves to be the most sensitive to appearance in the system of moisture, including its trace amounts. The characteristic time of the heating is of the order of 10 ms. The measurement procedure is based on a method that consists in automatic search for spontaneous boiling-up temperature of the oil accompanied by a characteristic response signal. The results were interpreted by formal correlation of the measured values with an array of calibration data obtained in similar experiments with well-defined oil samples. An experimental method for application of the device has been developed that takes into account technological factors, such as comparatively high values of the flow rate and the temperature of the oil in locations of the oil drain from bearings, the variability of these values, and the variety of noise types that accompany the operation of the thermal power equipment that complicate the online measurements. Tests of the device were carried out in locations of oil drain from supporting bearings. The test results have demonstrated the possibility of applying the device directly in the oil system of a turbine and provided a practical basis for development of a system of multipoint control of the technological scheme in real time.

  6. SEMICONDUCTOR DEVICES Density-controllable nonvolatile memory devices having metal nanocrystals through chemical synthesis and assembled by spin-coating technique

    Science.gov (United States)

    Guangli, Wang; Yubin, Chen; Yi, Shi; Lin, Pu; Lijia, Pan; Rong, Zhang; Youdou, Zheng

    2010-12-01

    A novel two-step method is employed, for the first time, to fabricate nonvolatile memory devices that have metal nanocrystals. First, size-averaged Au nanocrystals are synthesized chemically; second, they are assembled into memory devices by a spin-coating technique at room temperature. This attractive approach makes it possible to tailor the diameter and control the density of nanocrystals individually. In addition, processes at room temperature prevent Au diffusion, which is a main concern for the application of metal nanocrystal-based memory. The experimental results, both the morphology characterization and the electrical measurements, reveal that there is an optimum density of nanocrystal monolayer to balance between long data retention and a large hysteresis memory window. At the same time, density-controllable devices could also feed the preferential emphasis on either memory window or retention time. All these facts confirm the advantages and novelty of our two-step method.

  7. Feasibility study of molecular memory device based on DNA using methylation to store information

    Science.gov (United States)

    Jiang, Liming; Qiu, Wanzhi; Al-Dirini, Feras; Hossain, Faruque M.; Evans, Robin; Skafidas, Efstratios

    2016-07-01

    DNA, because of its robustness and dense information storage capability, has been proposed as a potential candidate for next-generation storage media. However, encoding information into the DNA sequence requires molecular synthesis technology, which to date is costly and prone to synthesis errors. Reading the DNA strand information is also complex. Ideally, DNA storage will provide methods for modifying stored information. Here, we conduct a feasibility study investigating the use of the DNA 5-methylcytosine (5mC) methylation state as a molecular memory to store information. We propose a new 1-bit memory device and study, based on the density functional theory and non-equilibrium Green's function method, the feasibility of electrically reading the information. Our results show that changes to methylation states lead to changes in the peak of negative differential resistance which can be used to interrogate memory state. Our work demonstrates a new memory concept based on methylation state which can be beneficial in the design of next generation DNA based molecular electronic memory devices.

  8. A high performance triboelectric nanogenerator for self-powered non-volatile ferroelectric transistor memory

    Science.gov (United States)

    Fang, Huajing; Li, Qiang; He, Wenhui; Li, Jing; Xue, Qingtang; Xu, Chao; Zhang, Lijing; Ren, Tianling; Dong, Guifang; Chan, H. L. W.; Dai, Jiyan; Yan, Qingfeng

    2015-10-01

    We demonstrate an integrated module of self-powered ferroelectric transistor memory based on the combination of a ferroelectric FET and a triboelectric nanogenerator (TENG). The novel TENG was made of a self-assembled polystyrene nanosphere array and a poly(vinylidene fluoride) porous film. Owing to this unique structure, it exhibits an outstanding performance with an output voltage as high as 220 V per cycle. Meanwhile, the arch-shaped TENG is shown to be able to pole a bulk ferroelectric 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-PT) single crystal directly. Based on this effect, a bottom gate ferroelectric FET was fabricated using pentacene as the channel material and a PMN-PT single crystal as the gate insulator. Systematic tests illustrate that the ON/OFF current ratio of this transistor memory element is approximately 103. More importantly, we demonstrate the feasibility to switch the polarization state of this FET gate insulator, namely the stored information, by finger tapping the TENG with a designed circuit. These results may open up a novel application of TENGs in the field of self-powered memory systems.We demonstrate an integrated module of self-powered ferroelectric transistor memory based on the combination of a ferroelectric FET and a triboelectric nanogenerator (TENG). The novel TENG was made of a self-assembled polystyrene nanosphere array and a poly(vinylidene fluoride) porous film. Owing to this unique structure, it exhibits an outstanding performance with an output voltage as high as 220 V per cycle. Meanwhile, the arch-shaped TENG is shown to be able to pole a bulk ferroelectric 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-PT) single crystal directly. Based on this effect, a bottom gate ferroelectric FET was fabricated using pentacene as the channel material and a PMN-PT single crystal as the gate insulator. Systematic tests illustrate that the ON/OFF current ratio of this transistor memory element is approximately 103. More importantly, we demonstrate the

  9. Organic ferroelectric opto-electronic memories

    Directory of Open Access Journals (Sweden)

    Kamal Asadi

    2011-12-01

    Full Text Available Memory is a prerequisite for many electronic devices. Organic non-volatile memory devices based on ferroelectricity are a promising approach towards the development of a low-cost memory technology based on a simple cross-bar array. In this review article we discuss the latest developments in this area with a focus on the most promising opto-electronic device concept, i.e., bistable rectifying diodes. The integration of these diodes into larger memory arrays is discussed. Through a clever design of the electrodes we demonstrate light emitting diodes with integrated built-in switches that can be applied in signage applications.

  10. Next generation Associative Memory devices for the FTK tracking processor of the ATLAS experiment

    CERN Document Server

    Andreani, A; The ATLAS collaboration; Beccherle, B; Beretta, M; Citterio, M; Crescioli, F; Colombo, A; Giannetti, P; Liberali, V; Shojaii, J; Stabile, A

    2013-01-01

    The AMchip is a VLSI device that implements the associative memory function, a special content addressable memory specifically designed for high energy physics applications and first used in the CDF experiment at Tevatron. The 4th generation of AMchip has been developed for the core pattern recognition stage of the Fast TracKer (FTK) processor: a hardware processor for online reconstruction of particle trajectories at the ATLAS experiment at LHC. We present the architecture, design considerations, power consumption and performance measurements of the 4th generation of AMchip. We present also the design innovations toward the 5th generation and the first prototype results.

  11. Design and verification of a shape memory polymer peripheral occlusion device.

    Science.gov (United States)

    Landsman, Todd L; Bush, Ruth L; Glowczwski, Alan; Horn, John; Jessen, Staci L; Ungchusri, Ethan; Diguette, Katelin; Smith, Harrison R; Hasan, Sayyeda M; Nash, Daniel; Clubb, Fred J; Maitland, Duncan J

    2016-10-01

    Shape memory polymer foams have been previously investigated for their safety and efficacy in treating a porcine aneurysm model. Their biocompatibility, rapid thrombus formation, and ability for endovascular catheter-based delivery to a variety of vascular beds makes these foams ideal candidates for use in numerous embolic applications, particularly within the peripheral vasculature. This study sought to investigate the material properties, safety, and efficacy of a shape memory polymer peripheral embolization device in vitro. The material characteristics of the device were analyzed to show tunability of the glass transition temperature (Tg) and the expansion rate of the polymer to ensure adequate time to deliver the device through a catheter prior to excessive foam expansion. Mechanical analysis and flow migration studies were performed to ensure minimal risk of vessel perforation and undesired thromboembolism upon device deployment. The efficacy of the device was verified by performing blood flow studies that established affinity for thrombus formation and blood penetration throughout the foam and by delivery of the device in an ultrasound phantom that demonstrated flow stagnation and diversion of flow to collateral pathways.

  12. 4D Printing of Shape Memory-Based Personalized Endoluminal Medical Devices.

    Science.gov (United States)

    Zarek, Matt; Mansour, Nicola; Shapira, Shir; Cohn, Daniel

    2017-01-01

    The convergence of additive manufacturing and shape-morphing materials is promising for the advancement of personalized medical devices. The capability to transform 3D objects from one shape to another, right off the print bed, is known as 4D printing. Shape memory thermosets can be tailored to have a range of thermomechanical properties favorable to medical devices, but processing them is a challenge because they are insoluble and do not flow at any temperature. This study presents here a strategy to capitalize on a series of medical imaging modalities to construct a printable shape memory endoluminal device, exemplified by a tracheal stent. A methacrylated polycaprolactone precursor with a molecular weight of 10 000 g mol(-1) is printed with a UV-LED stereolithography printer based on anatomical data. This approach converges with the zeitgeist of personalized medicine and it is anticipated that it will broadly expand the application of shape memory-exhibiting biomedical devices to myriad clinical indications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Microstructural effect of gadolinium oxide nanocrystals upon annealing on electrical properties of memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Michael R.S. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Liu, Chuan-Pu, E-mail: cpliu@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China); Wang, Jer-Chyi; Chen, Yu-Kai; Lai, Chao-Sung [Department of Electronic Engineering, Chang-Gung University, Kweishan 333, Taoyuan, Taiwan (China); Fang, Yu-Ching; Shu, Li [Materials and Electro-Optics Research Division, Chung Shan Institute of Science and Technology, Longtan 325, Taoyuan, Taiwan (China)

    2012-06-30

    The microstructure evolution of sputtered gadolinium oxide nanocrystal (NC) memory devices upon annealing has been characterized in detail by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). TEM results indicate that the as-deposited film is composed of metallic Gd clusters embedded in an amorphous Gd{sub x}O{sub y} matrix. The Gd clusters undergo phase transformation to oxide NCs upon annealing, reaching a maximum density of 7.9-9.1 Multiplication-Sign 10{sup 11} cm{sup -2} at 850 Degree-Sign C, which is consistent with the largest memory window width. Upon annealing at even higher temperature, TEM diffraction patterns and XPS composition profiles indicate apparent Si diffusion into the NC layer, probably from the SiO{sub 2} tunneling oxide or the Si substrate, leading to the formation of gadolinium silicate NCs. The presence of silicate NCs gradually deteriorates the device performance due to the reduction of barrier confinement for stored charges, although the dot density is only marginally decreased. The results suggest that the optimum memory device performance is dominated by not only the most considered size and density of NCs, but also the composition and phase inside. - Highlights: Black-Right-Pointing-Pointer Memory devices with gadolinium oxide nanocrystals have been realized. Black-Right-Pointing-Pointer X-ray photoelectron spectroscopy shows annealing-induced interdiffusion of Si. Black-Right-Pointing-Pointer Transmission electron microscopy indicates the formation of gadolinium silicate. Black-Right-Pointing-Pointer Migrating Si from substrate can further modify NC phase upon annealing. Black-Right-Pointing-Pointer Both nanocrystal density and phase influence the device performance.

  14. Magnetic resonance flow velocity and temperature mapping of a shape memory polymer foam device

    Directory of Open Access Journals (Sweden)

    Wilson Thomas S

    2009-12-01

    Full Text Available Abstract Background Interventional medical devices based on thermally responsive shape memory polymer (SMP are under development to treat stroke victims. The goals of these catheter-delivered devices include re-establishing blood flow in occluded arteries and preventing aneurysm rupture. Because these devices alter the hemodynamics and dissipate thermal energy during the therapeutic procedure, a first step in the device development process is to investigate fluid velocity and temperature changes following device deployment. Methods A laser-heated SMP foam device was deployed in a simplified in vitro vascular model. Magnetic resonance imaging (MRI techniques were used to assess the fluid dynamics and thermal changes associated with device deployment. Results Spatial maps of the steady-state fluid velocity and temperature change inside and outside the laser-heated SMP foam device were acquired. Conclusions Though non-physiological conditions were used in this initial study, the utility of MRI in the development of a thermally-activated SMP foam device has been demonstrated.

  15. The influence of Ti doping and annealing on Ce2Ti2O7 flash memory devices

    Science.gov (United States)

    Kao, Chyuan Haur; Chen, Su Zhien; Luo, Yang; Chiu, Wang Ting; Chiu, Shih Wei; Chen, I. Chien; Lin, Chan-Yu; Chen, Hsiang

    2017-02-01

    In this research, a CeO2 film with Ti doping was used as a trapping layer in metal oxide high-K-oxide-Si (MOHOS)-type memory devices. Since incorporation of Ti atoms into the film could fix dangling bonds and defects, the Ce2Ti2O7 trapping layer with annealing treatment could have a larger memory window and a faster programming/erasing speed. To confirm the origin, multiple material analyses indicate that annealing at an appropriate temperature and Ti doping could enhance crystallization. The Ce2Ti2O7-based memory device is promising for future industrial flash memory applications.

  16. Low voltage lead titanate/Si one-transistor ferroelectric memory with good device characteristics

    Science.gov (United States)

    Sun, C. L.; Chen, S. Y.; Liao, C. C.; Chin, Albert

    2004-11-01

    We have developed one-transistor ferroelectric memory using lead titanate (PTO) as a gate dielectric directly formed on Si without any buffer layer. The PTO/Si metal-oxide-semiconductor field-effect transistor memory has shown a large threshold voltage shift of 1.6 V at only ±4V program/erase voltages. The corresponding good interface was achieved by lowering the anneal temperature to 450 °C. Besides the sharp capacitance change of 0.17μF/Vcm2, it was also evidenced by the high mobility of 169cm2/Vs close to high-κ HfO2. In addition, long retention >1000s and endurance >1011 stress cycles in the device suggested good memory characteristics.

  17. Chemical-Vapor-Deposited Graphene as Charge Storage Layer in Flash Memory Device

    Directory of Open Access Journals (Sweden)

    W. J. Liu

    2016-01-01

    Full Text Available We demonstrated a flash memory device with chemical-vapor-deposited graphene as a charge trapping layer. It was found that the average RMS roughness of block oxide on graphene storage layer can be significantly reduced from 5.9 nm to 0.5 nm by inserting a seed metal layer, which was verified by AFM measurements. The memory window is 5.6 V for a dual sweep of ±12 V at room temperature. Moreover, a reduced hysteresis at the low temperature was observed, indicative of water molecules or −OH groups between graphene and dielectric playing an important role in memory windows.

  18. Modeling of electron conduction in contact resistive random access memory devices as random telegraph noise.

    Science.gov (United States)

    Tseng, Yuan Heng; Shen, Wen Chao; Lin, Chrong Jung

    2012-04-01

    The intense development and study of resistive random access memory (RRAM) devices has opened a new era in semiconductor memory manufacturing. Resistive switching and carrier conduction inside RRAM films have become critical issues in recent years. Electron trapping/detrapping behavior is observed and investigated in the proposed contact resistive random access memory (CR-RAM) cell. Through the fitting of the space charge limiting current (SCLC) model, and analysis in terms of the random telegraph noise (RTN) model, the temperature-dependence of resistance levels and the high-temperature data retention behavior of the contact RRAM film are successfully and completely explained. Detail analyses of the electron capture and emission from the traps by forward and reverse read measurements provide further verifications for hopping conduction mechanism and current fluctuation discrepancies.

  19. High-performance memory device using graphene oxide flakes sandwiched polymethylmethacrylate layers.

    Science.gov (United States)

    Valanarasu, S; Kulandaisamy, I; Kathalingam, A; Rhee, Jin-Koo; Vijayan, T A; Chandramohan, R

    2013-10-01

    Organic bistable devices (OBDs) using graphene oxide (GO) flakes sandwiched polymethylmethacrylate (PMMA) films were fabricated. These devices exhibited two accessible conducting states, that is, a low-conductivity (OFF) state and a high-conductivity (ON) state. The devices can be switched to ON state under a negative electrical sweep; it can also be reset to the initial OFF state by a reverse (positive) electrical sweep. Detailed I-V measurements have shown that in ITO/PMMA/GO/PMMA/Al sandwiches the resistive switching originates from the formation and rupture of conducting filaments. The ON/OFF ratio of the OBDs was approximately 5 x 10(3), reproducibility of more than 10(5) cycles, and retention time of 10(4) s. These properties show that the device is promising for high-density, low-cost memory application.

  20. Structural damping with shape-memory alloys: one class of devices

    Science.gov (United States)

    Krumme, Robert; Hayes, Jack; Sweeney, Steve

    1995-05-01

    Passive control of the dynamic response of civil structures utilizing shape-memory alloy (SMA) damping techniques is reviewed. An important class of SMA damper -- the center- tapped (CT) device -- is described. Coverage includes: (1) characterization of damping requirements and passive damping approaches for civil structures; (2) characterization of SMA material behaviors relevant to civil structural applications; (3) overview of our SMA passive damping device technology and description of the center-tapped device operation and structure; (4) precis of an experimental program conducted to verify the CT device behavior, the detailed results of which are reported in another paper by the Earthquake Engineering Research Center; (5) review of a design study of SMA passive damping for retrofit of an extant nonductile concrete building.

  1. A non-volatile organic electrochemical device as a low-voltage artificial synapse for neuromorphic computing

    Science.gov (United States)

    van de Burgt, Yoeri; Lubberman, Ewout; Fuller, Elliot J.; Keene, Scott T.; Faria, Grégorio C.; Agarwal, Sapan; Marinella, Matthew J.; Alec Talin, A.; Salleo, Alberto

    2017-04-01

    The brain is capable of massively parallel information processing while consuming only ~1-100 fJ per synaptic event. Inspired by the efficiency of the brain, CMOS-based neural architectures and memristors are being developed for pattern recognition and machine learning. However, the volatility, design complexity and high supply voltages for CMOS architectures, and the stochastic and energy-costly switching of memristors complicate the path to achieve the interconnectivity, information density, and energy efficiency of the brain using either approach. Here we describe an electrochemical neuromorphic organic device (ENODe) operating with a fundamentally different mechanism from existing memristors. ENODe switches at low voltage and energy (500 distinct, non-volatile conductance states within a ~1 V range, and achieves high classification accuracy when implemented in neural network simulations. Plastic ENODes are also fabricated on flexible substrates enabling the integration of neuromorphic functionality in stretchable electronic systems. Mechanical flexibility makes ENODes compatible with three-dimensional architectures, opening a path towards extreme interconnectivity comparable to the human brain.

  2. Impact of return on long-memory data set of volatility of Dhaka Stock Exchange market with the role of financial institutions: an empirical analysis

    Directory of Open Access Journals (Sweden)

    Muhammad Mahboob Ali

    2017-08-01

    Full Text Available The current study intends to empirically test a relationship between long-memory features in returns and volatility of Dhaka Stock Exchange market. As such, the study uses the ARFIMA-FIGARCH and FIPARCH structure for the daily data ranging from 15 December 2003 to July 31, 2013 of Dhaka Stock Exchange market index, i.e., DSE General Index (DGEN. The observed indication assembled from long-memory tests supports the occurrence of long memory in Bangladesh stock returns. The study aims at doing research work with long-memory data set, as it provides a superior strategy, as well as gives real picture with short-memory data set. Moreover, the backup indication for existence of long memory in both return and volatility denies the efficient market hypothesis of Fama (1970 that the future return and volatility values are unpredictable. Extra measures ought to be given for the smooth functioning of the Dhaka Stock Exchange market so that both individual and institutional investors can get congenial atmosphere to invest. Authors’ suggested that Bangladesh Bank must play vital role as share market of Bangladesh is dominated by banking shares and in case of other listed shares of the Dhaka Stock Exchange, market authority should deal with transparently and fairly so that the market can be transformed into strong efficient market. This requires suitable directives, groundwork, removing malpractices and also implementation of investors’ friendly decisions. Further, fiscal policy of the country should be pro investor friendly, as well as monetary policy should work as complementary towards investment at stock exchange market as suggested by the authors.

  3. Magnetic Shape Memory Alloys as smart materials for micro-positioning devices

    Directory of Open Access Journals (Sweden)

    A. Hubert

    2012-10-01

    Full Text Available In the field of microrobotics, actuators based on smart materials are predominant because of very good precision, integration capabilities and high compactness. This paper presents the main characteristics of Magnetic Shape Memory Alloys as new candidates for the design of micromechatronic devices. The thermo-magneto-mechanical energy conversion process is first presented followed by the adequate modeling procedure required to design actuators. Finally, some actuators prototypes realized at the Femto-ST institute are presented, including a push-pull bidirectional actuator. Some results on the control and performances of these devices conclude the paper.

  4. Development and process control of magnetic tunnel junctions for magnetic random access memory devices

    Science.gov (United States)

    Kula, Witold; Wolfman, Jerome; Ounadjela, Kamel; Chen, Eugene; Koutny, William

    2003-05-01

    We report on the development and process control of magnetic tunnel junctions (MTJs) for magnetic random access memory (MRAM) devices. It is demonstrated that MTJs with high magnetoresistance ˜40% at 300 mV, resistance-area product (RA) ˜1-3 kΩ μm2, low intrinsic interlayer coupling (Hin) ˜2-3 Oe, and excellent bit switching characteristics can be developed and fully integrated with complementary metal-oxide-semiconductor circuitry into MRAM devices. MTJ uniformity and repeatability level suitable for mass production has been demonstrated with the advanced processing and monitoring techniques.

  5. Metal-free, single-polymer device exhibits resistive memory effect

    KAUST Repository

    Bhansali, Unnat Sampatraj

    2013-12-23

    All-polymer, write-once-read-many times resistive memory devices have been fabricated on flexible substrates using a single polymer, poly(3,4- ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). Spin-cast or inkjet-printed films of solvent-modified PEDOT:PSS are used as electrodes, while the unmodified or as-is PEDOT:PSS is used as the semiconducting active layer. The all-polymer devices exhibit an irreversible but stable transition from a low resistance state (ON) to a high resistance state (OFF) at low voltages caused by an electric-field-induced morphological rearrangement of PEDOT and PSS at the electrode interface. However, in the metal-PEDOT:PSS-metal devices, we have shown a metal filament formation switching the device from an initial high resistance state (OFF) to the low resistance state (ON). The all-PEDOT:PSS memory device has low write voltages (<3 V), high ON/OFF ratio (>10 3), good retention characteristics (>10 000 s), and stability in ambient storage (>3 months). © 2013 American Chemical Society.

  6. Interfacial behavior of resistive switching in ITO-PVK-Al WORM memory devices

    Science.gov (United States)

    Whitcher, T. J.; Woon, K. L.; Wong, W. S.; Chanlek, N.; Nakajima, H.; Saisopa, T.; Songsiriritthigul, P.

    2016-02-01

    Understanding the mechanism of resistive switching in a memory device is fundamental in order to improve device performance. The mechanism of current switching in a basic organic write-once read-many (WORM) memory device is investigated by determining the energy level alignments of indium tin oxide (ITO), poly(9-vinylcarbazole) (PVK) and aluminum (Al) using x-ray and ultraviolet photoelectron spectroscopy, current-voltage characterization and Auger depth profiling. The current switching mechanism was determined to be controlled by the interface between the ITO and the PVK. The electric field applied across the device causes the ITO from the uneven surface of the anode to form metallic filaments through the PVK, causing a shorting effect within the device leading to increased conduction. This was found to be independent of the PVK thickness, although the switch-on voltage was non-linearly dependent on the thickness. The formation of these filaments also caused the destruction of the interfacial dipole at the PVK-Al interface.

  7. Metal oxide resistive random access memory based synaptic devices for brain-inspired computing

    Science.gov (United States)

    Gao, Bin; Kang, Jinfeng; Zhou, Zheng; Chen, Zhe; Huang, Peng; Liu, Lifeng; Liu, Xiaoyan

    2016-04-01

    The traditional Boolean computing paradigm based on the von Neumann architecture is facing great challenges for future information technology applications such as big data, the Internet of Things (IoT), and wearable devices, due to the limited processing capability issues such as binary data storage and computing, non-parallel data processing, and the buses requirement between memory units and logic units. The brain-inspired neuromorphic computing paradigm is believed to be one of the promising solutions for realizing more complex functions with a lower cost. To perform such brain-inspired computing with a low cost and low power consumption, novel devices for use as electronic synapses are needed. Metal oxide resistive random access memory (ReRAM) devices have emerged as the leading candidate for electronic synapses. This paper comprehensively addresses the recent work on the design and optimization of metal oxide ReRAM-based synaptic devices. A performance enhancement methodology and optimized operation scheme to achieve analog resistive switching and low-energy training behavior are provided. A three-dimensional vertical synapse network architecture is proposed for high-density integration and low-cost fabrication. The impacts of the ReRAM synaptic device features on the performances of neuromorphic systems are also discussed on the basis of a constructed neuromorphic visual system with a pattern recognition function. Possible solutions to achieve the high recognition accuracy and efficiency of neuromorphic systems are presented.

  8. Efficient mask data preparation for variable shaped e-beam writing system focusing on memory devices

    Science.gov (United States)

    Jang, Tae H.; Lee, Jong-Bae; Shin, Jae-Pil; Yoo, Kwang-Jai; Jung, Dai-Hyun; Park, Yong-Hee; Yoo, Moon-Hyun; Kong, Jeong-Taek

    2003-12-01

    To cope with sub-100nm technology in the mask making industry, a variable shaped e-beam(VSB) writing system is one of the solutions through its high-electron voltage. The VSB writing system, however, requires a different mask data preparation comparing to the traditional raster scan writing system. Due to the differences, mask making industries are confronted with difficult problems, such as explosively increasing data volume and unpredictably growing mask making time especially for memory devices. VSB system's writing time is determined by the conversion from CAD data to VSB data. The conversion time, especially for the critical layers of memory devices, mostly depends on to what extent optimize CAD data to enhance writing system throughput. For this reason, to shorten the unpredictably growing mask making time, a data conversion tool must consider the throughput of data conversion and mask writing at the same time. To reduce the data conversion time while retaining the optimal writing time, we propose the mixed-mode data processing method, in which the hierarchical data operation is applied on memory cells and the flat data operation is applied on peripheral circuits. For each area, different fracturing strategies are applied, too. The polygon-aware fracturing method is applied to improve the CD control within memory cells, and the selective one-directional fracturing method is applied to reduce the writing time within peripheral circuits.

  9. Germanium nanoparticles grown at different deposition times for memory device applications

    Energy Technology Data Exchange (ETDEWEB)

    Mederos, M., E-mail: melissa.mederos@gmail.com [Center for Semiconductor Components and Nanotechnology (CCSNano), University of Campinas (Unicamp), Rua João Pandia Calógeras 90, Campinas, CEP: 13083-870, São Paulo (Brazil); Mestanza, S.N.M. [Federal University of ABC (UFABC), Rua Santa Adélia 166, Bangu, Santo André, CEP: 09210-170, São Paulo (Brazil); Lang, R. [Institute of Science and Technology, Federal University of São Paulo (UNIFESP), Rua Talim, 330, São José dos Campos, CEP: 12231-280, São Paulo (Brazil); Doi, I.; Diniz, J.A. [Center for Semiconductor Components and Nanotechnology (CCSNano), University of Campinas (Unicamp), Rua João Pandia Calógeras 90, Campinas, CEP: 13083-870, São Paulo (Brazil); School of Electrical and Computer Engineering, University of Campinas (Unicamp), Av. Albert Einstein 400, Campinas, CEP: 13083-852, São Paulo (Brazil)

    2016-07-29

    In the present work, circular Metal-Oxide-Semiconductor capacitors with 200 μm of diameter and germanium (Ge) nanoparticles (NPs) embedded in the gate oxide are studied for memory applications. Optimal process parameters are investigated for Ge NPs growing by low pressure chemical vapor deposition at different deposition times. Photoluminescence measurements showed room-temperature size-dependent green-red region bands attributed to quantum confinement effects present in the NPs. High-frequency capacitance versus voltage measurements demonstrated the memory effects on the MOS structures due to the presence of Ge NPs in the gate oxide acting as discrete floating gates. Current versus voltage measurements confirmed the Fowler-Nordheim tunneling as the programming mechanism of the devices. - Highlights: • Ge nanoparticles with high density and uniforms sizes were obtained by LPCVD. • Room-temperature size-dependent bands of photoluminescence were observed. • MOS capacitors with Ge nanoparticles embedded in the oxide were fabricated. • Ge nanoparticles are the main responsible for the memory properties in the devices. • Fowler-Nordheim tunneling is the conduction mechanism observed on the devices.

  10. InAs quantum dots as charge storing elements for applications in flash memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Sk Masiul; Biswas, Pranab [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Banerji, P., E-mail: pallab@matsc.iitkgp.ernet.in [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Chakraborty, S. [Applied Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Sector-I, Kolkata 700 064 (India)

    2015-08-15

    Graphical abstract: - Highlights: • Catalyst-free growth of InAs quantum dots was carried out on high-k ZrO{sub 2}. • Memory device with InAs quantum dots as charge storage nodes are fabricated. • Superior memory window, low leakage and reasonably good retention were observed. • Carrier transport phenomena are explained in both program and erase operations. - Abstract: InAs quantum dots (QDs) were grown by metal organic chemical vapor deposition technique to use them as charge storage nodes. Uniform QDs were formed with average diameter 5 nm and height 5–10 nm with a density of 2 × 10{sup 11} cm{sup −2}. The QDs were grown on high-k dielectric layer (ZrO{sub 2}), which was deposited onto ultra-thin GaP passivated p-GaAs (1 0 0) substrate. A charge storage device with the structure Metal/ZrO{sub 2}/InAs QDs/ZrO{sub 2}/(GaP)GaAs/Metal was fabricated. The devices containing InAs QDs exhibit superior memory window, low leakage current density along with reasonably good charge retention. A suitable electronic band diagram corresponding to programming and erasing operations was proposed to explain the operation.

  11. The Nano-Memory Devices of a Single Wall and Peapod Structural Carbon Nanotube Field Effect Transistor

    Science.gov (United States)

    Lee, C. H.; Kang, K. T.; Park, K. S.; Kim, M. S.; Kim, H. S.; Kim, H. G.; Fischer, J. E.; Johnson, A. T.

    2003-08-01

    The rediscovery and the memory application of single walled carbon nanotubes (SWNTs) give a new method in nanoelectronics applications. At first we will report the memory effects of a SWNT, and attempt to use this property in a memory device. To use a SWNT field effect transistor (FET) as a charge-storage memory device, the device operates by injecting electrons from the nanotube channel of a TubeFET into charge traps on the surface of the SiO2 gate dielectric, thus shifting the threshold voltage. This memory can be written and erased many times, and has a hold time of hundreds of seconds at room temperature. At second we have attempted to make a Peapod tubeFET. It is the structure that a C60 was contained within the tube and separated from it by a graphitic Van der Waals gap. I-V property of the Peapod shows semiconducting property.

  12. Exploring the Future of Out-of-Core Computing with Compute-Local Non-Volatile Memory

    Directory of Open Access Journals (Sweden)

    Myoungsoo Jung

    2014-01-01

    Full Text Available Drawing parallels to the rise of general purpose graphical processing units (GPGPUs as accelerators for specific high-performance computing (HPC workloads, there is a rise in the use of non-volatile memory (NVM as accelerators for I/O-intensive scientific applications. However, existing works have explored use of NVM within dedicated I/O nodes, which are distant from the compute nodes that actually need such acceleration. As NVM bandwidth begins to out-pace point-to-point network capacity, we argue for the need to break from the archetype of completely separated storage. Therefore, in this work we investigate co-location of NVM and compute by varying I/O interfaces, file systems, types of NVM, and both current and future SSD architectures, uncovering numerous bottlenecks implicit in these various levels in the I/O stack. We present novel hardware and software solutions, including the new Unified File System (UFS, to enable fuller utilization of the new compute-local NVM storage. Our experimental evaluation, which employs a real-world Out-of-Core (OoC HPC application, demonstrates throughput increases in excess of an order of magnitude over current approaches.

  13. Self-activated mesh device using shape memory alloy for periosteal expansion osteogenesis.

    Science.gov (United States)

    Yamauchi, Kensuke; Takahashi, Tetsu; Tanaka, Kenko; Nogami, Shinnosuke; Kaneuji, Takeshi; Kanetaka, Hiroyasu; Miyazaki, Toshiki; Lethaus, Bernd; Kessler, Peter

    2013-07-01

    The present study evaluated the use of this self-activated shape memory alloy (SMA) device, with a focus on its effects in the region under the periosteum. Twelve Japanese white rabbits were used in this study. The device was inserted under the periosteum at the forehead. In the experimental group, the device was pushed, bent, and attached to the bone surface and fixed with a titanium screw. In control group, the device was only inserted under the periosteum. After 14 days, the screw was removed and the mesh was activated in the experimental group. Rabbits were sacrificed 5 and 8 weeks after the operation and newly formed bone was histologically and radiographically evaluated. The quantitative data by the area and the occupation of newly formed bone indicated that the experimental group had a higher volume of new bone than the control group at each consolidation period. Histologically, some newly formed bone was observed and most of the subperiosteal space underneath the device was filled with fibrous tissue, and a thin layer of immature bone was observed in the control group. In the experimental group, multiple dome-shaped bones, outlined by thin and scattered trabeculae, were clearly observed under the SMA mesh device. The use of self-activated devices for the periosteal expansion technique may make it possible to avoid donor site morbidity, trans-skin activation rods, any bone-cutting procedure, and the following intermittent activation procedure.

  14. Charging effect in Au nanoparticle memory device with biomolecule binding mechanism.

    Science.gov (United States)

    Jung, Sung Mok; Kim, Hyung-Jun; Kim, Bong-Jin; Yoon, Tae-Sik; Kim, Yong-Sang; Lee, Hyun Ho

    2011-07-01

    Organic memory device having gold nanoparticle (Au NPs) has been introduced in the structure of metal-pentacene-insulator-silicon (MPIS) capacitor device, where the Au NPs layer was formed by a new bonding method. Biomolecule binding mechanism between streptavidin and biotin was used as a strong binding method for the formation of monolayered Au NPs on polymeric dielectric of poly vinyl alcohol (PVA). The self-assembled Au NPs was functioned to show storages of charge in the MPIS device. The binding by streptavidin and biotin was confirmed by AFM and UV-VIS. The UV-VIS absorption of the Au NPs was varied at 515 nm and 525 nm depending on the coating of streptavidin. The AFM image showed no formation of multi-stacked layers of the streptavidin-capped Au NPs on biotin-NHS layer. Capacitance-voltage (C-V) performance of the memory device was measured to investigate the charging effect from Au NPs. In addition, charge retention by the Au NPs storage was tested to show 10,000 s in the C-V curve.

  15. Observation of nonvolatile resistive memory switching characteristics in Ag/graphene-oxide/Ag devices.

    Science.gov (United States)

    Venugopal, Gunasekaran; Kim, Sang-Jae

    2012-11-01

    In this paper, we report highly stable and bipolar resistive switching effects of Ag/Graphene oxide thinfilm/Ag devices. The graphene-oxide (GO) thinfilms were prepared on Ag/SiO2/Si substrates by spin-coating technique. The Ag/GO/Ag devices showed a steady and bipolar resistive switching characteristic. The resistance switching from low resistance state (LRS) and high resistance state (HRS) with the resistance ratio of HRS to LRS of about 10 which was attained at a voltage bias of 0.1 V. Based on the filamentary conduction model, the dominant conduction mechanism of switching effect was well explained. Our results show GO can be a promising candidate for future development of nonvolatile memory devices.

  16. Influence of heavy ion flux on single event effect testing in memory devices

    Science.gov (United States)

    Luo, Jie; Liu, Jie; Sun, Youmei; Hou, Mingdong; Xi, Kai; Liu, Tianqi; Wang, Bin; Ye, Bing

    2017-09-01

    The natural space presents a particle flux variable environment and choosing a suitable flux value for ground-based single event experiments is an unresolved problem so far. In this work, various types of memory devices have been tested over the ion flux range from 10 to 105 ions/(cm2·s) using different ions covering LET from 10.1 to 99.8 MeV·cm2/mg. It was found that for most devices the error rates of single event upsets are affected by the applied flux value. And the effect involving flux becomes prominent as it is increased above 103 ions/(cm2·s). Different devices behave differently as the flux is increased and the flux effect depends strongly on the LET of the impinging ions. The results concluded in this experiment are discussed in detail and recommendations for choosing appropriate experimental flux are given.

  17. Needle-type extraction device for the purge and trap analysis of 23 volatile organic compounds in tap water.

    Science.gov (United States)

    Ueta, Ikuo; Razak, Nurhafizza Abd; Mizuguchi, Ayako; Kawakubo, Susumu; Saito, Yoshihiro; Jinno, Kiyokatsu

    2013-11-22

    We developed a rapid determination technique for trace volatile organic compounds (VOCs) in tap water by introducing a novel needle-type extraction device coupled to a purge-and-trap method. To extract a wide range of VOCs, a new extraction needle containing particles of divinylbenzene and activated carbon was developed in this study. During the active sampling of the headspace gas in a glass vial by the extraction needle, pure N2 gas was used for purging the aqueous sample. After the optimization of several experimental parameters, such as the addition of the salt and conditions of dry purging and desorption, the extraction performance of the device and method was evaluated for 23 VOCs that are typically found in tap water samples. The quantification limits of the method were 0.6 μg/L for 1,1-dichloroethylene and less than 0.5 μg/L for other VOCs, with good repeatability being confirmed for all the target compounds. Taking advantage of the excellent recovery of VOCs, the determination of VOCs in real tap water samples was carried out successfully. Because the developed method does not require sample heating and/or cryogenic focusing, simple and rapid analyses can be performed along with satisfactory sensitivity for typical tap water samples.

  18. Shape memory alloy-based biopsy device for active locomotive intestinal capsule endoscope.

    Science.gov (United States)

    Le, Viet Ha; Hernando, Leon-Rodriguez; Lee, Cheong; Choi, Hyunchul; Jin, Zhen; Nguyen, Kim Tien; Go, Gwangjun; Ko, Seong-Young; Park, Jong-Oh; Park, Sukho

    2015-03-01

    Recently, capsule endoscopes have been used for diagnosis in digestive organs. However, because a capsule endoscope does not have a locomotive function, its use has been limited to small tubular digestive organs, such as small intestine and esophagus. To address this problem, researchers have begun studying an active locomotive intestine capsule endoscope as a medical instrument for the whole gastrointestinal tract. We have developed a capsule endoscope with a small permanent magnet that is actuated by an electromagnetic actuation system, allowing active and flexible movement in the patient's gut environment. In addition, researchers have noted the need for a biopsy function in capsule endoscope for the definitive diagnosis of digestive diseases. Therefore, this paper proposes a novel robotic biopsy device for active locomotive intestine capsule endoscope. The proposed biopsy device has a sharp blade connected with a shape memory alloy actuator. The biopsy device measuring 12 mm in diameter and 3 mm in length was integrated into our capsule endoscope prototype, where the device's sharp blade was activated and exposed by the shape memory alloy actuator. Then the electromagnetic actuation system generated a specific motion of the capsule endoscope to extract the tissue sample from the intestines. The final biopsy sample tissue had a volume of about 6 mm(3), which is a sufficient amount for a histological analysis. Consequently, we proposed the working principle of the biopsy device and conducted an in-vitro biopsy test to verify the feasibility of the biopsy device integrated into the capsule endoscope prototype using the electro-magnetic actuation system. © IMechE 2015.

  19. Enhanced organic memory devices (OMEM) with a photochromic perhydro DTE as a transduction layer (Conference Presentation)

    Science.gov (United States)

    Cordes, Sandra; Kranz, Darius; Maibach, Eduard; Kempf, Maxim; Meerholz, Klaus

    2016-09-01

    In modern electronic systems memory elements are of fundamental importance for data storage. Especially solution-processable nonvolatile organic memories, which are inexpensive and can be manufactured on flexible substrates, are a promising alternative to brittle inorganic devices. Organic photochromic switchable compounds, mostly dithienylethenes (DTEs), are thermally stable, fatigue resistant and can undergo an electrically- or/and photo-induced ring-opening and -closing reaction which results in a change of energy levels. Due to the energetic difference in the highest occupied molecular orbital (HOMO) between the open and closed isomer, the DTE layer can be exploited as a switchable hole injection barrier that controls the electrical current in the diode. We demonstrated that a light-emitting organic memory (LE-OMEM) device with a perfluoro DTE transduction layer can be switched electrically via high current densities pulses and optically by irradiated light, with impressive current ON/OFF Ratios (OOR) of 10Λ2, 10Λ4 respectively. Currently we aim to minimize the barrier of the ON state and maximize the barrier of the OFF state by designing DTE molecules with larger differences in the HOMO energies of the two isomers yielding improved OOR values. By synthesizing perhydro derivates of DTE we achieved molecules with high HOMO levels and large ΔHOMO energies providing OMEM devices with excellent physical properties (OOR 1.4 x higher than perfluoro DTE). Due to the high HOMO level of the perhydro DTE utilization of hole transport layers (HTLs) is not necessary and thus manufacturing of OMEM devices is simplified.

  20. Unusual magnetic behavior in a chiral-based magnetic memory device

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Dor, Oren; Yochelis, Shira [Department of Applied Physics, Center of Nanoscience and Nanotechnology, Hebrew University, Jerusalem 91904 (Israel); Felner, Israel, E-mail: Israel.felner@mail.huij.ac.il [“Racah” Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Paltiel, Yossi [Department of Applied Physics, Center of Nanoscience and Nanotechnology, Hebrew University, Jerusalem 91904 (Israel)

    2016-01-15

    In recent years chiral molecules were found to act as efficient spin filters. Using a multilayer structure with chiral molecules magnetic memory was realized. Observed rare magnetic phenomena in a chiral-based magnetic memory device was reported by O-Ben Dor et. al in Nature Commun, 4, 2256 (2013). This multi-layered device is built from α-helix L-polyalanine (AHPA-L) adsorbed on gold, Al{sub 2}O{sub 3} (7 nm) and Ni (30 nm) layers. It was shown that certain temperature range the FC branch crosses the magnetic peak (at 55 K) observed in the ZFC curve thus ZFC>FC. We show here that in another similar multi-layered material, at low applied field, the ZFC curve lies above the FC one up to 70 K. The two features have the same origin and the crucial necessary components to exhibit them are: AHPA-L and 30 nm Ni layered thick. Similar effects were also reported in sulfur doped amorphous carbon. A comparison between the two systems and the ingredients for these peculiar observations is discussed. - Highlights: • The highlights of the present manuscript is the peculiar magnetic behavior observed in a multilayer structure with chiral molecules, magnetic memory. • It is shown that certain temperature range the FC branch crosses the magnetic peak (at 55 K) observed in the ZFC curve thus ZFC>FC. • Similar effects were also reported in sulfur doped amorphous carbon.

  1. Synthesis of Gold Nanoparticles Capped with Quaterthiophene for Transistor and Resistor Memory Devices

    Directory of Open Access Journals (Sweden)

    Mai Ha Hoang

    2016-01-01

    Full Text Available Recently, the fabrication of nonvolatile memory devices based on gold nanoparticles has been intensively investigated. In this work, we report on the design and synthesis of new semiconducting quaterthiophene incorporating hexyl thiol group (4TT. Gold nanoparticles capped with 4TT (4TTG were prepared in a two-phase liquid-liquid system. These nanoparticles have diameters in the range 2–6 nm and are well dispersed in the poly(3-hexylthiophene (P3HT host matrix. The intermolecular interaction between 4TT and P3HT could enhance the charge-transport between gold nanoparticles and P3HT. Transfer curve of transistor memory device made of 4TTG/P3HT hybrid film exhibited significant current hysteresis, probably arising from the energy level barrier at 4TTG/P3HT interface. Additionally, the polymer memory resistor structure with an active layer consisting of 4TTG and P3HT displayed a remarkable electrical bistable behavior.

  2. An annulus fibrosus closure device based on a biodegradable shape-memory polymer network.

    Science.gov (United States)

    Sharifi, Shahriar; van Kooten, Theo G; Kranenburg, Hendrik-Jan C; Meij, Björn P; Behl, Marc; Lendlein, Andreas; Grijpma, Dirk W

    2013-11-01

    Injuries to the intervertebral disc caused by degeneration or trauma often lead to tearing of the annulus fibrosus (AF) and extrusion of the nucleus pulposus (NP). This can compress nerves and cause lower back pain. In this study, the characteristics of poly(D,L-lactide-co-trimethylene carbonate) networks with shape-memory properties have been evaluated in order to prepare biodegradable AF closure devices that can be implanted minimally invasively. Four different macromers with (D,L-lactide) to trimethylene carbonate (DLLA:TMC) molar ratios of 80:20, 70:30, 60:40 and 40:60 with terminal methacrylate groups and molecular weights of approximately 30 kg mol(-1) were used to prepare the networks by photo-crosslinking. The mechanical properties of the samples and their shape-memory properties were determined at temperatures of 0 °C and 40 °C by tensile tests- and cyclic, thermo-mechanical measurements. At 40 °C all networks showed rubber-like behavior and were flexible with elastic modulus values of 1.7-2.5 MPa, which is in the range of the modulus values of human annulus fibrosus tissue. The shape-memory characteristics of the networks were excellent with values of the shape-fixity and the shape-recovery ratio higher than 98 and 95%, respectively. The switching temperatures were between 10 and 39 °C. In vitro culture and qualitative immunocytochemistry of human annulus fibrosus cells on shape-memory films with DLLA:TMC molar ratios of 60:40 showed very good ability of the networks to support the adhesion and growth of human AF cells. When the polymer network films were coated by adsorption of fibronectin, cell attachment, cell spreading, and extracellular matrix production was further improved. Annulus fibrosus closure devices were prepared from these AF cell-compatible materials by photo-polymerizing the reactive precursors in a mold. Insertion of the multifunctional implant in the disc of a cadaveric canine spine showed that these shape-memory devices could be

  3. Inductively heated shape memory polymer for the magnetic actuation of medical devices.

    Science.gov (United States)

    Buckley, Patrick R; McKinley, Gareth H; Wilson, Thomas S; Small, Ward; Benett, William J; Bearinger, Jane P; McElfresh, Michael W; Maitland, Duncan J

    2006-10-01

    Presently, there is interest in making medical devices such as expandable stents and intravascular microactuators from shape memory polymer (SMP). One of the key challenges in realizing SMP medical devices is the implementation of a safe and effective method of thermally actuating various device geometries in vivo. A novel scheme of actuation by Curie-thermoregulated inductive heating is presented. Prototype medical devices made from SMP loaded with nickel zinc ferrite ferromagnetic particles were actuated in air by applying an alternating magnetic field to induce heating. Dynamic mechanical thermal analysis was performed on both the particle-loaded and neat SMP materials to assess the impact of the ferrite particles on the mechanical properties of the samples. Calorimetry was used to quantify the rate of heat generation as a function of particle size and volumetric loading of ferrite particles in the SMP. These tests demonstrated the feasibility of SMP actuation by inductive heating. Rapid and uniform heating was achieved in complex device geometries and particle loading up to 10% volume content did not interfere with the shape recovery of the SMP.

  4. Inductively Heated Shape Memory Polymer for the Magnetic Actuation of Medical Devices

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, P; Mckinley, G; Wilson, T; Small, W; Benett, W; Bearinger, J; McElfresh, M; Maitland, D

    2005-09-06

    Presently there is interest in making medical devices such as expandable stents and intravascular microactuators from shape memory polymer (SMP). One of the key challenges in realizing SMP medical devices is the implementation of a safe and effective method of thermally actuating various device geometries in vivo. A novel scheme of actuation by Curie-thermoregulated inductive heating is presented. Prototype medical devices made from SMP loaded with Nickel Zinc ferrite ferromagnetic particles were actuated in air by applying an alternating magnetic field to induce heating. Dynamic mechanical thermal analysis was performed on both the particle-loaded and neat SMP materials to assess the impact of the ferrite particles on the mechanical properties of the samples. Calorimetry was used to quantify the rate of heat generation as a function of particle size and volumetric loading of ferrite particles in the SMP. These tests demonstrated the feasibility of SMP actuation by inductive heating. Rapid and uniform heating was achieved in complex device geometries and particle loading up to 10% volume content did not interfere with the shape recovery of the SMP.

  5. Self-formed conductive nanofilaments in (Bi, Mn)Ox for ultralow-power memory devices

    KAUST Repository

    Kang, Chen Fang

    2015-04-01

    Resistive random access memory (RRAM) is one of the most promising candidates as a next generation nonvolatile memory (NVM), owing to its superior scalability, low power consumption and high speed. From the materials science point of view, to explore optimal RRAM materials is still essential for practical application. In this work, a new material (Bi, Mn)Ox (BMO) is investigated and several key performance characteristics of Pt/BMO/Pt structured device, including switching performance, retention and endurance, are examined in details. Furthermore, it has been confirmed by high-resolution transmission electron microscopy that the underlying switching mechanism is attributed to formation and disruption of metallic conducting nanofilaments (CNFs). More importantly, the power dissipation for each CNF is as low as 3.8/20fJ for set/reset process, and a realization of cross-bar structure memory cell is demonstrated to prove the downscaling ability of proposed RRAM. These distinctive properties have important implications for understanding switching mechanisms and implementing ultralow power-dissipation RRAM based on BMO. •Self-formed conductive nanofilaments in BMO show ultralow-power memory feature.•The feature of 10nm in diameter and an average 20-30nm spacing of CNFs suggests the compatibility with the current CMOS technologies.•Power dissipation for each CNF is as low as 3.8/20fJ for set/reset process•A realization of cross-bar structure memory cell is demonstrated to prove the downscaling ability of proposed RRAM. © 2015 Elsevier Ltd.

  6. CMOS Compatible Nonvolatile Memory Devices Based on SiO2/Cu/SiO2 Multilayer Films

    Institute of Scientific and Technical Information of China (English)

    WANG Yan; LIU Qi; LV Hang-Bing; LONG Shi-Bing; ZHANG Sen; LI Ying-Tao; LIAN Wen-Tai; YANG Jian-Hong; LIU Ming

    2011-01-01

    We systematically investigate the resistive switching characteristics of SiO2 films with a Cu/SiO2/Cu/SiO2/Pt multilayer structure. The device exhibits good resistive switching performances,including a high ON/OFF resistance ratio (>103),good retention characteristic (>104 s),satisfactory switching endurance (>200cycles),a fast programming speed (<100ns) and a high device yield (~100%).Considering these results,SiO2-based memories have highly promising applications for nonvolatile memory devices.

  7. Solid-state non-volatile electronically programmable reversible variable resistance device

    Science.gov (United States)

    Ramesham, Rajeshuni (Inventor); Thakoor, Sarita (Inventor); Daud, Taher (Inventor); Thakoor, Aniklumar P. (Inventor)

    1989-01-01

    A solid-state variable resistance device (10) whose resistance can be repeatedly altered by a control signal over a wide range, and which will remain stable after the signal is removed, is formed on an insulated layer (14), supported on a substrate (12) and comprises a set of electrodes (16a, 16b) connected by a layer (18) of material, which changes from an insulator to a conductor upon the injection of ions, covered by a layer (22) of material with insulating properties which permit the passage of ions, overlaid by an ion donor material (20). The ion donor material is overlaid by an insulating layer (24) upon which is deposited a control gate (26) located above the contacts. In a preferred embodiment, the variable resistance material comprises WO.sub.3, the ion donor layer comprises Cr.sub.2 O.sub.3, and the layers sandwiching the ion donor layer comprise silicon monoxide. When a voltage is applied to the gate, the resistance between the electrode contacts changes, decreasing with positive voltage and increasing with negative voltage.

  8. Lead-free epitaxial ferroelectric material integration on semiconducting (100) Nb-doped SrTiO3 for low-power non-volatile memory and efficient ultraviolet ray detection.

    Science.gov (United States)

    Kundu, Souvik; Clavel, Michael; Biswas, Pranab; Chen, Bo; Song, Hyun-Cheol; Kumar, Prashant; Halder, Nripendra N; Hudait, Mantu K; Banerji, Pallab; Sanghadasa, Mohan; Priya, Shashank

    2015-07-23

    We report lead-free ferroelectric based resistive switching non-volatile memory (NVM) devices with epitaxial (1-x)BaTiO3-xBiFeO3 (x = 0.725) (BT-BFO) film integrated on semiconducting (100) Nb (0.7%) doped SrTiO3 (Nb:STO) substrates. The piezoelectric force microscopy (PFM) measurement at room temperature demonstrated ferroelectricity in the BT-BFO thin film. PFM results also reveal the repeatable polarization inversion by poling, manifesting its potential for read-write operation in NVM devices. The electroforming-free and ferroelectric polarization coupled electrical behaviour demonstrated excellent resistive switching with high retention time, cyclic endurance, and low set/reset voltages. X-ray photoelectron spectroscopy was utilized to determine the band alignment at the BT-BFO and Nb:STO heterojunction, and it exhibited staggered band alignment. This heterojunction is found to behave as an efficient ultraviolet photo-detector with low rise and fall time. The architecture also demonstrates half-wave rectification under low and high input signal frequencies, where the output distortion is minimal. The results provide avenue for an electrical switch that can regulate the pixels in low or high frequency images. Combined this work paves the pathway towards designing future generation low-power ferroelectric based microelectronic devices by merging both electrical and photovoltaic properties of BT-BFO materials.

  9. Lead-free epitaxial ferroelectric material integration on semiconducting (100) Nb-doped SrTiO3 for low-power non-volatile memory and efficient ultraviolet ray detection

    Science.gov (United States)

    Kundu, Souvik; Clavel, Michael; Biswas, Pranab; Chen, Bo; Song, Hyun-Cheol; Kumar, Prashant; Halder, Nripendra N.; Hudait, Mantu K.; Banerji, Pallab; Sanghadasa, Mohan; Priya, Shashank

    2015-07-01

    We report lead-free ferroelectric based resistive switching non-volatile memory (NVM) devices with epitaxial (1-x)BaTiO3-xBiFeO3 (x = 0.725) (BT-BFO) film integrated on semiconducting (100) Nb (0.7%) doped SrTiO3 (Nb:STO) substrates. The piezoelectric force microscopy (PFM) measurement at room temperature demonstrated ferroelectricity in the BT-BFO thin film. PFM results also reveal the repeatable polarization inversion by poling, manifesting its potential for read-write operation in NVM devices. The electroforming-free and ferroelectric polarization coupled electrical behaviour demonstrated excellent resistive switching with high retention time, cyclic endurance, and low set/reset voltages. X-ray photoelectron spectroscopy was utilized to determine the band alignment at the BT-BFO and Nb:STO heterojunction, and it exhibited staggered band alignment. This heterojunction is found to behave as an efficient ultraviolet photo-detector with low rise and fall time. The architecture also demonstrates half-wave rectification under low and high input signal frequencies, where the output distortion is minimal. The results provide avenue for an electrical switch that can regulate the pixels in low or high frequency images. Combined this work paves the pathway towards designing future generation low-power ferroelectric based microelectronic devices by merging both electrical and photovoltaic properties of BT-BFO materials.

  10. Chemical insight into origin of forming-free resistive random-access memory devices

    KAUST Repository

    Wu, X.

    2011-09-29

    We demonstrate the realization of a forming-step free resistive random access memory (RRAM) device using a HfOx/TiOx/HfOx/TiOxmultilayer structure, as a replacement for the conventional HfOx-based single layer structure. High-resolution transmission electron microscopy (HRTEM), along with electron energy loss spectroscopy(EELS)analysis has been carried out to identify the distribution and the role played by Ti in the RRAM stack. Our results show that Ti out-diffusion into the HfOx layer is the chemical cause of forming-free behavior. Moreover, the capability of Ti to change its ionic state in HfOx eases the reduction-oxidation (redox) reaction, thus lead to the RRAM devices performance improvements.

  11. Stretchable carbon nanotube charge-trap floating-gate memory and logic devices for wearable electronics.

    Science.gov (United States)

    Son, Donghee; Koo, Ja Hoon; Song, Jun-Kyul; Kim, Jaemin; Lee, Mincheol; Shim, Hyung Joon; Park, Minjoon; Lee, Minbaek; Kim, Ji Hoon; Kim, Dae-Hyeong

    2015-05-26

    Electronics for wearable applications require soft, flexible, and stretchable materials and designs to overcome the mechanical mismatch between the human body and devices. A key requirement for such wearable electronics is reliable operation with high performance and robustness during various deformations induced by motions. Here, we present materials and device design strategies for the core elements of wearable electronics, such as transistors, charge-trap floating-gate memory units, and various logic gates, with stretchable form factors. The use of semiconducting carbon nanotube networks designed for integration with charge traps and ultrathin dielectric layers meets the performance requirements as well as reliability, proven by detailed material and electrical characterizations using statistics. Serpentine interconnections and neutral mechanical plane layouts further enhance the deformability required for skin-based systems. Repetitive stretching tests and studies in mechanics corroborate the validity of the current approaches.

  12. Direct observation of nanometer-scale Joule and Peltier effects in phase change memory devices

    Science.gov (United States)

    Grosse, Kyle L.; Xiong, Feng; Hong, Sungduk; King, William P.; Pop, Eric

    2013-05-01

    We measure power dissipation in phase change memory (PCM) devices by scanning Joule expansion microscopy (SJEM) with ˜50 nm spatial and 0.2 K temperature resolution. The temperature rise in the Ge2Sb2Te5 (GST) is dominated by Joule heating, but at the GST-TiW contacts it is a combination of Peltier and current crowding effects. Comparison of SJEM and electrical measurements with simulations of the PCM devices uncovers a thermopower of ˜350 μV K-1 and a contact resistance of ˜2.0 × 10-8 Ω m2 (to TiW) for 25 nm thick films of face centered-cubic crystalline GST. Knowledge of such nanometer-scale Joule, Peltier, and current crowding effects is essential for energy-efficient design of future PCM technology.

  13. The effect of medical device dose-memory functions on patients’ adherence to treatment, confidence, and disease self-management

    Directory of Open Access Journals (Sweden)

    Hall RL

    2014-05-01

    Full Text Available Rebecca L Hall,1 Thomas Willgoss,1 Louise J Humphrey,1 Jens Harald Kongsø2 1Adelphi Values, Adelphi Mill, Bollington, Cheshire, UK; 2Novo Nordisk A/S, Novo Allé, Bagsværd, Denmark Background: Adherence to treatment is an important issue in chronic disease management and an indicator of patients’ ability to self-manage their condition and treatment. Some drug-dispensing and drug-delivery devices have been designed to support patients’ medication-taking behavior by including dose-memory and combined dose-memory and dose-reminder functions, which electronically store, and visually display dose-history information, enabling the patient to review, monitor, and/or be actively reminded about their medication doses.Purpose: This literature review explored the role and impact of these devices on patients’ treatment adherence, confidence with, and self-management of their condition and treatment.Materials and methods: A search of MEDLINE, Embase, and PsycINFO was performed to identify articles published in English from 2003–2013 that studied the effect of devices with dose-memory and combined dose-memory and dose-reminder functions on treatment adherence and users’ (patients, health care professionals [HCPs], and caregivers confidence, self-management behavior, and attitudes.Results: The database searches yielded 940 abstracts from which 13 articles met the inclusion criteria and were retained. Devices with dose-memory and combined dose-memory and dose-reminder functions were found to improve self-reported and electronically monitored treatment adherence in chronic conditions such as asthma, diabetes, and HIV. The ability of the devices to provide dose-history information and active medication reminders was considered valuable in disease management by patients, caregivers, and HCPs. The devices were found to enhance patients’ confidence in, and motivation to manage their medication and condition, and help reduce forgotten or incorrect

  14. Organic ferroelectric memory devices with inkjet-printed polymer electrodes on flexible substrates

    KAUST Repository

    Bhansali, Unnat Sampatraj

    2013-05-01

    Drop-on-demand piezoelectric inkjet-printing technique has been used to fabricate a functional cross-bar array of all-organic ferroelectric memory devices. The polymer-ferroelectric-polymer device consists of a ferroelectric copolymer P(VDF-TrFE) film sandwiched between inkjet-patterned, continuous, orthogonal lines of PEDOT:PSS polymer as the bottom and top electrodes. These devices exhibit well-saturated hysteresis curves with a maximum remnant polarization (Pr) = 6.7 μC/cm2, coercive field (E c) = 55 MV/m and a peak capacitance density of 45 nF/cm2. Our polarization fatigue measurements show that these devices retain ∼100% and 45% of their initial Pr values after 103 and 10 5 stress cycles, respectively. The overall performance and polarization retention characteristics of these ferroelectric capacitors with inkjet-printed polymer electrodes are comparable to metal and spin-cast polymer electrodes suggesting their potential use in large-area flexible electronics. © 2013 Elsevier Ltd. All rights reserved.

  15. Scalability of valence change memory: From devices to tip-induced filaments

    Directory of Open Access Journals (Sweden)

    U. Celano

    2016-08-01

    Full Text Available Since the early days of the investigation on resistive switching (RS, the independence of the ON-state resistance with actual cell area has been a trademark of filamentary-switching. However, with the continuous downscaling of the memory cell down to 10 x 10 nm2 and below, the persistence of this phenomena raises intriguing questions on the conductive filaments (CFs and its dimensions. Particularly, the cell functionality demonstrated at relatively high switching current (> 100 μA implies a high current density (> 106 A/cm2 inside a CF supposedly confined in few hundreds on nm3. We previously demonstrated a methodology for the direct observation of CFs in integrated devices namely scalpel SPM, which overcomes most of the characterization challenges imposed by the device structure and the small CF lateral dimensions. In this letter, we use scalpel SPM to clarify the scaling potential of HfO2-based valence change memory (VCM by characterization of CFs programmed at relatively high switching current and by AFM tip-induced RS experiments. Besides the demonstration of a remarkable scaling potential for the VCM technology, our results are also used to clarify the present understanding on the AFM-based experiments.

  16. Scalability of valence change memory: From devices to tip-induced filaments

    Science.gov (United States)

    Celano, U.; Fantini, A.; Degraeve, R.; Jurczak, M.; Goux, L.; Vandervorst, W.

    2016-08-01

    Since the early days of the investigation on resistive switching (RS), the independence of the ON-state resistance with actual cell area has been a trademark of filamentary-switching. However, with the continuous downscaling of the memory cell down to 10 x 10 nm2 and below, the persistence of this phenomena raises intriguing questions on the conductive filaments (CFs) and its dimensions. Particularly, the cell functionality demonstrated at relatively high switching current (> 100 μA) implies a high current density (> 106 A/cm2) inside a CF supposedly confined in few hundreds on nm3. We previously demonstrated a methodology for the direct observation of CFs in integrated devices namely scalpel SPM, which overcomes most of the characterization challenges imposed by the device structure and the small CF lateral dimensions. In this letter, we use scalpel SPM to clarify the scaling potential of HfO2-based valence change memory (VCM) by characterization of CFs programmed at relatively high switching current and by AFM tip-induced RS experiments. Besides the demonstration of a remarkable scaling potential for the VCM technology, our results are also used to clarify the present understanding on the AFM-based experiments.

  17. Integration of lead-free ferroelectric on HfO2/Si (100) for high performance non-volatile memory applications

    OpenAIRE

    Kundu, Souvik; Maurya, Deepam; Clavel, Michael; Zhou, Yuan; Nripendra N. Halder; Hudait, Mantu K.; Banerji, Pallab; Priya, Shashank

    2015-01-01

    We introduce a novel lead-free ferroelectric thin film (1-x)BaTiO3-xBa(Cu1/3Nb2/3)O3 (x = 0.025) (BT-BCN) integrated on to HfO2 buffered Si for non-volatile memory (NVM) applications. Piezoelectric force microscopy (PFM), x-ray diffraction, and high resolution transmission electron microscopy were employed to establish the ferroelectricity in BT-BCN thin films. PFM study reveals that the domains reversal occurs with 180° phase change by applying external voltage, demonstrating its effectivene...

  18. Reversible strain-induced magnetization switching in FeGa nanomagnets: Pathway to a rewritable, non-volatile, non-toggle, extremely low energy straintronic memory

    Science.gov (United States)

    Ahmad, Hasnain; Atulasimha, Jayasimha; Bandyopadhyay, Supriyo

    2015-12-01

    We report reversible strain-induced magnetization switching between two stable/metastable states in ~300 nm sized FeGa nanomagnets delineated on a piezoelectric PMN-PT substrate. Voltage of one polarity applied across the substrate generates compressive strain in a nanomagnet and switches its magnetization to one state, while voltage of the opposite polarity generates tensile strain and switches the magnetization back to the original state. The two states can encode the two binary bits, and, using the right voltage polarity, one can write either bit deterministically. This portends an ultra-energy-efficient non-volatile “non-toggle” memory.

  19. Nano-Floating Gate Memory Devices Composed of ZnO Thin-Film Transistors on Flexible Plastics

    Directory of Open Access Journals (Sweden)

    Park Byoungjun

    2011-01-01

    Full Text Available Abstract Nano-floating gate memory devices were fabricated on a flexible plastic substrate by a low-temperature fabrication process. The memory characteristics of ZnO-based thin-film transistors with Al nanoparticles embedded in the gate oxides were investigated in this study. Their electron mobility was found to be 0.18 cm2/V·s and their on/off ratio was in the range of 104–105. The threshold voltages of the programmed and erased states were negligibly changed up to 103 cycles. The flexibility, memory properties, and low-temperature fabrication of the nano-floating gate memory devices described herein suggest that they have potential applications for future flexible integrated electronics.

  20. Memory

    Science.gov (United States)

    ... it has to decide what is worth remembering. Memory is the process of storing and then remembering this information. There are different types of memory. Short-term memory stores information for a few ...

  1. Nonvolatile write-once-read-many times memory devices based on the composites of poly(4-vinylphenol)/Vulcan XC-72.

    Science.gov (United States)

    Song, Sunghoon; Kim, Tae-Wook; Cho, Byungjin; Ji, Yongsung; Lee, Takhee

    2011-05-01

    We fabricated write-once-read-many times (WORM) type organic memory devices in 8 x 8 cross-bar structure. The active material for organic based WORM memory devices is mixture of both poly(4-vinyphenol) (PVP) and Vulcan XC-72s. From the electrical characteristics of the WORM memory devices, we observed two different resistance states, low resistance state and high resistance state, with six orders of ON/OFF ratio (I(ON)/I(OFF) - 10(6)). In addition, the WORM memory devices were maintained for longer than 50000 seconds without any serious degradation.

  2. Next generation spin torque memories

    CERN Document Server

    Kaushik, Brajesh Kumar; Kulkarni, Anant Aravind; Prajapati, Sanjay

    2017-01-01

    This book offers detailed insights into spin transfer torque (STT) based devices, circuits and memories. Starting with the basic concepts and device physics, it then addresses advanced STT applications and discusses the outlook for this cutting-edge technology. It also describes the architectures, performance parameters, fabrication, and the prospects of STT based devices. Further, moving from the device to the system perspective it presents a non-volatile computing architecture composed of STT based magneto-resistive and all-spin logic devices and demonstrates that efficient STT based magneto-resistive and all-spin logic devices can turn the dream of instant on/off non-volatile computing into reality.

  3. Semiconductor-Free Nonvolatile Resistive Switching Memory Devices Based on Metal Nanogaps Fabricated on Flexible Substrates via Adhesion Lithography

    KAUST Repository

    Semple, James

    2017-01-02

    Electronic memory cells are of critical importance in modern-day computing devices, including emerging technology sectors such as large-area printed electronics. One technology that has being receiving significant interest in recent years is resistive switching primarily due to its low dimensionality and nonvolatility. Here, we describe the development of resistive switching memory device arrays based on empty aluminum nanogap electrodes. By employing adhesion lithography, a low-temperature and large-area compatible nanogap fabrication technique, dense arrays of memory devices are demonstrated on both rigid and flexible plastic substrates. As-prepared devices exhibit nonvolatile memory operation with stable endurance, resistance ratios >10⁴ and retention times of several months. An intermittent analysis of the electrode microstructure reveals that controlled resistive switching is due to migration of metal from the electrodes into the nanogap under the application of an external electric field. This alternative form of resistive random access memory is promising for use in emerging sectors such as large-area electronics as well as in electronics for harsh environments, e.g., space, high/low temperature, magnetic influences, radiation, vibration, and pressure.

  4. Effect of hydrogen ion beam treatment on Si nanocrystal/SiO{sub 2} superlattice-based memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Sheng-Wen; Chen, Hui-Ju; Wu, Hsuan-Ta; Chuang, Bing-Ru; Shih, Chuan-Feng, E-mail: cfshih@mail.ncku.edu.tw

    2016-03-30

    Graphical abstract: - Highlights: • Memory window and retention properties are improved employing HIBAS technique. • The O/Si ratio and radiative recombination are changed by HIBAS. • Memory properties are affected not only by Si NCs and O/Si ratio but also the RDCs. • The mechanism of hydrogen ion beam alters the memory properties is investigated. - Abstract: This study presents a novel route for synthesizing silicon-rich oxide (SRO)/SiO{sub 2} superlattice-based memory devices with an improved memory window and retention properties. The SiO{sub 2} and SRO superlattices are deposited by reactive sputtering. Specifically, the hydrogen ion beam is used to irradiate the SRO layer immediately after its deposition in the vacuum chamber. The use of the hydrogen ion beam was determined to increase oxygen content and the density of the Si nanocrystals. The memory window increased from 16 to 25.6 V, and the leakage current decreased significantly by two orders, to under ±20 V, for the hydrogen ion beam-prepared devices. This study investigates the mechanism into how hydrogen ion beam treatment alters SRO films and influences memory properties.

  5. GA-based optimum design of a shape memory alloy device for seismic response mitigation

    Science.gov (United States)

    Ozbulut, O. E.; Roschke, P. N.; Y Lin, P.; Loh, C. H.

    2010-06-01

    Damping systems discussed in this work are optimized so that a three-story steel frame structure and its shape memory alloy (SMA) bracing system minimize response metrics due to a custom-tailored earthquake excitation. Multiple-objective numerical optimization that simultaneously minimizes displacements and accelerations of the structure is carried out with a genetic algorithm (GA) in order to optimize SMA bracing elements within the structure. After design of an optimal SMA damping system is complete, full-scale experimental shake table tests are conducted on a large-scale steel frame that is equipped with the optimal SMA devices. A fuzzy inference system is developed from data collected during the testing to simulate the dynamic material response of the SMA bracing subcomponents. Finally, nonlinear analyses of a three-story braced frame are carried out to evaluate the performance of comparable SMA and commonly used steel braces under dynamic loading conditions and to assess the effectiveness of GA-optimized SMA bracing design as compared to alternative designs of SMA braces. It is shown that peak displacement of a structure can be reduced without causing significant acceleration response amplification through a judicious selection of physical characteristics of the SMA devices. Also, SMA devices provide a recentering mechanism for the structure to return to its original position after a seismic event.

  6. Coexistence of diode-like volatile and multilevel nonvolatile resistive switching in a ZrO2/TiO2 stack structure

    Science.gov (United States)

    Li, Yingtao; Yuan, Peng; Fu, Liping; Li, Rongrong; Gao, Xiaoping; Tao, Chunlan

    2015-10-01

    Diode-like volatile resistive switching as well as nonvolatile resistive switching behaviors in a Cu/ZrO2/TiO2/Ti stack are investigated. Depending on the current compliance during the electroforming process, either volatile resistive switching or nonvolatile resistive switching is observed. With a lower current compliance (diode-like volatile resistive switching with a rectifying ratio over 106. The permanent transition from volatile to nonvolatile resistive switching can be obtained by applying a higher current compliance of 100 μA. Furthermore, by using different reset voltages, the Cu/ZrO2/TiO2/Ti device exhibits multilevel memory characteristics with high uniformity. The coexistence of nonvolatile multilevel memory and diode-like volatile resistive switching behaviors in the same Cu/ZrO2/TiO2/Ti device opens areas of applications in high-density storage, logic circuits, neural networks, and passive crossbar memory selectors.

  7. The effect of medical device dose-memory functions on patients' adherence to treatment, confidence, and disease self-management.

    Science.gov (United States)

    Hall, Rebecca L; Willgoss, Thomas; Humphrey, Louise J; Kongsø, Jens Harald

    2014-01-01

    Adherence to treatment is an important issue in chronic disease management and an indicator of patients' ability to self-manage their condition and treatment. Some drug-dispensing and drug-delivery devices have been designed to support patients' medication-taking behavior by including dose-memory and combined dose-memory and dose-reminder functions, which electronically store, and visually display dose-history information, enabling the patient to review, monitor, and/or be actively reminded about their medication doses. This literature review explored the role and impact of these devices on patients' treatment adherence, confidence with, and self-management of their condition and treatment. A search of MEDLINE, Embase, and PsycINFO was performed to identify articles published in English from 2003-2013 that studied the effect of devices with dose-memory and combined dose-memory and dose-reminder functions on treatment adherence and users' (patients, health care professionals [HCPs], and caregivers) confidence, self-management behavior, and attitudes. The database searches yielded 940 abstracts from which 13 articles met the inclusion criteria and were retained. Devices with dose-memory and combined dose-memory and dose-reminder functions were found to improve self-reported and electronically monitored treatment adherence in chronic conditions such as asthma, diabetes, and HIV. The ability of the devices to provide dose-history information and active medication reminders was considered valuable in disease management by patients, caregivers, and HCPs. The devices were found to enhance patients' confidence in, and motivation to manage their medication and condition, and help reduce forgotten or incorrect medication dosing. The incorporation of dose-memory and combined dose-memory and dose-reminder functions in drug-delivery devices can improve patients' adherence, confidence, and self-management behavior. They can target non-intentional barriers to adherence and can

  8. An ultra-low-power area-efficient non-volatile memory in a 0.18 μ m single-poly CMOS process for passive RFID tags

    Institute of Scientific and Technical Information of China (English)

    Jia Xiaoyun; Feng Peng; Zhang Shengguang; Wu Nanjian; Zhao Baiqin; Liu Su

    2013-01-01

    This paper presents an ultra-low-power area-efficient non-volatile memory (NVM) in a 0.18μm singlepoly standard CMOS process for passive radio frequency identification (RFID) tags.In the memory cell,a novel low-power operation method is proposed to realize bi-directional Fowler-Nordheim tunneling during write operation.Furthermore,the cell is designed with PMOS transistors and coupling capacitors to minimize its area.In order to improve its reliability,the cell consists of double floating gates to store the data,and the 1 kbit NVM was implemented in a 0.18μm single-poly standard CMOS process.The area of the memory cell and 1 kbit memory array is 96μm2 and 0.12 mm2,respectively.The measured results indicate that the program/erase voltage ranges from 5 to 6 V.The power consumption of the read/write operation is 0.19μW/0.69 μW at a read/write rate of (268 kb/s)/(3.0 kb/s).

  9. Diode-less bilayer oxide (WO(x)-NbO(x)) device for cross-point resistive memory applications.

    Science.gov (United States)

    Liu, Xinjun; Sadaf, Sharif Md; Son, Myungwoo; Shin, Jungho; Park, Jubong; Lee, Joonmyoung; Park, Sangsu; Hwang, Hyunsang

    2011-11-25

    The combination of a threshold switching device and a resistive switching (RS) device was proposed to suppress the undesired sneak current for the integration of bipolar RS cells in a cross-point array type memory. A simulation for this hybrid-type device shows that the matching of key parameters between switch element and memory element is an important issue. Based on the threshold switching oxides, a conceptual structure with a simple metal-oxide 1-oxide 2-metal stack was provided to accommodate the evolution trend. We show that electroformed W-NbO(x)-Pt devices can simultaneously exhibit both threshold switching and memory switching. A qualitative model was suggested to elucidate the unique properties in a W-NbO(x)-Pt stack, where threshold switching is associated with a localized metal-insulator transition in the NbO(x) bulk, and the bipolar RS derives from a redox at the tip of the localized filament at the WO(x)-NbO(x) interface. Such a simple metal-oxide-metal structure, with functionally separated bulk and interface effects, provides a fabrication advantage for future high-density cross-point memory devices.

  10. Wavelet analisys and HHG in nanorings Their applications in logic gates and memory mass devices

    CERN Document Server

    Cricchio, Dario

    2015-01-01

    We study the application of one nanoring driven by a laser field in different states of polarization in logic circuits. In particular we show that assigning boolean values to different state of the incident laser field and to the emitted signals, we can create logic gates such as OR, XOR and AND. We also show the possibility to make logic circuits such as half-adder and full-adder using one and two nanoring respectively. Using two nanorings we made the Toffoli gate. Finally we use the final angular momentum acquired by the electron to store information and hence show the possibility to use an array of nanorings as a mass memory device.

  11. Electrophysical Properties of Ge-Sb-Te Thin Films for Phase Change Memory Devices

    Science.gov (United States)

    Lazarenko, P. I.; Kozyukhin, S. A.; Sherchenkov, A. A.; Babich, A. V.; Timoshenkov, S. P.; Gromov, D. G.; Zabolotskaya, A. V.; Kozik, V. V.

    2017-01-01

    In this work, we studied temperature dependences of the resistivity and current-voltage characteristics of amorphous thin films based on the materials of a Ge-Sb-Te system of compositions GeSb4Te7 (GST147), GeSb2Te4 (GST124), and Ge2Sb2Te5 (GST225) applied in the phase change memory devices. The effect of changes in the composition of thin films on the crystallization temperature, resistivity of films in amorphous and crystalline states, and on the activation energy of conductivity is determined. It is found that the peculiarity of these materials is the mechanism of two-channel conductivity where the contribution to the conductivity is made by charge carriers excited into localized states in the band tails and by carriers of the delocalized states in the valence band.

  12. A CMOS-compatible poly-Si nanowire device with hybrid sensor/memory characteristics for System-on-Chip applications.

    Science.gov (United States)

    Chen, Min-Cheng; Chen, Hao-Yu; Lin, Chia-Yi; Chien, Chao-Hsin; Hsieh, Tsung-Fan; Horng, Jim-Tong; Qiu, Jian-Tai; Huang, Chien-Chao; Ho, Chia-Hua; Yang, Fu-Liang

    2012-01-01

    This paper reports a versatile nano-sensor technology using "top-down" poly-silicon nanowire field-effect transistors (FETs) in the conventional Complementary Metal-Oxide Semiconductor (CMOS)-compatible semiconductor process. The nanowire manufacturing technique reduced nanowire width scaling to 50 nm without use of extra lithography equipment, and exhibited superior device uniformity. These n type polysilicon nanowire FETs have positive pH sensitivity (100 mV/pH) and sensitive deoxyribonucleic acid (DNA) detection ability (100 pM) at normal system operation voltages. Specially designed oxide-nitride-oxide buried oxide nanowire realizes an electrically V(th)-adjustable sensor to compensate device variation. These nanowire FETs also enable non-volatile memory application for a large and steady V(th) adjustment window (>2 V Programming/Erasing window). The CMOS-compatible manufacturing technique of polysilicon nanowire FETs offers a possible solution for commercial System-on-Chip biosensor application, which enables portable physiology monitoring and in situ recording.

  13. A CMOS-Compatible Poly-Si Nanowire Device with Hybrid Sensor/Memory Characteristics for System-on-Chip Applications

    Directory of Open Access Journals (Sweden)

    Chia-Hua Ho

    2012-03-01

    Full Text Available This paper reports a versatile nano-sensor technology using “top-down” poly-silicon nanowire field-effect transistors (FETs in the conventional Complementary Metal-Oxide Semiconductor (CMOS-compatible semiconductor process. The nanowire manufacturing technique reduced nanowire width scaling to 50 nm without use of extra lithography equipment, and exhibited superior device uniformity. These n type polysilicon nanowire FETs have positive pH sensitivity (100 mV/pH and sensitive deoxyribonucleic acid (DNA detection ability (100 pM at normal system operation voltages. Specially designed oxide-nitride-oxide buried oxide nanowire realizes an electrically Vth-adjustable sensor to compensate device variation. These nanowire FETs also enable non-volatile memory application for a large and steady Vth adjustment window (>2 V Programming/Erasing window. The CMOS-compatible manufacturing technique of polysilicon nanowire FETs offers a possible solution for commercial System-on-Chip biosensor application, which enables portable physiology monitoring and in situ recording.

  14. Computational Analysis of Advanced Shape-Memory Alloy Devices Through a Robust Modeling Framework

    Science.gov (United States)

    Scalet, Giulia; Conti, Michele; Auricchio, Ferdinando

    2017-06-01

    Shape-memory alloys (SMA) provide significant advantages in various industrial fields, but their manufacturing and commercialization are currently hindered. This is attributed mainly to the poor knowledge of material behavior and the lack of standards in its mechanical characterization. SMA products are usually developed by trial-and-error testing to address specific design requirements, thus increasing costs and time. The development of simulation tools offers a possible solution to assist engineers and designers and allows to better understand SMA transformation phenomena. Accordingly, the purpose of the present paper is to numerically analyze and predict the response of spring-like actuators and septal occluders, which are industrial components exploiting the shape-memory and pseudoelastic properties of SMAs, respectively. The methodology includes two main stages: the implementation of the three-dimensional phenomenological model known as Souza- Auricchio model and the finite element modeling of the device. A discussion about the steps of each stage, as parameter identification and model generalizations, is provided. Validation results are presented through a comparison with the results of a performed experimental campaign. The framework proves good prediction capabilities and allows to reduce the number of experimental tests in the future.

  15. Effect of mechanical loads on stability of nanodomains in ferroelectric ultrathin films: towards flexible erasing of the non-volatile memories.

    Science.gov (United States)

    Chen, W J; Zheng, Yue; Xiong, W M; Feng, Xue; Wang, Biao; Wang, Ying

    2014-06-18

    Intensive investigations have been drawn on nanoscale ferroelectrics for their prospective applications such as developing memory devices. In contrast with the commonly used electrical means to process (i.e., read, write or erase) the information carried by ferroelectric domains, at present, mechanisms of non-electrical processing ferroelectric domains are relatively lacking. Here we make a systematical investigation on the stability of 180° cylindrical domains in ferroelectric nanofilms subjected to macroscopic mechanical loads, and explore the possibility of mechanical erasing. Effects of domain size, film thickness, temperature and different mechanical loads, including uniform strain, cylindrical bending and wavy bending, have been revealed. It is found that the stability of a cylindrical domain depends on its radius, temperature and film thickness. More importantly, mechanical loads have great controllability on the stability of cylindrical domains, with the critical radius nonlinearly sensitive to both strain and strain gradient. This indicates that erasing cylindrical domain can be achieved by changing the strain state of nanofilm. Based on the calculated phase diagrams, we successfully simulate several mechanical erasing processes on 4 × 4 bits memory devices. Our study sheds light on prospective device applications of ferroelectrics involving mechanical loads, such as flexible memory devices and other micro-electromechanical systems.

  16. Structural Phase Transition Effect on Resistive Switching Behavior of MoS2 -Polyvinylpyrrolidone Nanocomposites Films for Flexible Memory Devices.

    Science.gov (United States)

    Zhang, Peng; Gao, Cunxu; Xu, Benhua; Qi, Lin; Jiang, Changjun; Gao, Meizhen; Xue, Desheng

    2016-04-01

    The 2H phase and 1T phase coexisting in the same molybdenum disulfide (MoS2 ) nanosheets can influence the electronic properties of the materials. The 1T phase of MoS2 is introduced into the 2H-MoS2 nanosheets by two-step hydrothermal synthetic methods. Two types of nonvolatile memory effects, namely write-once read-many times memory and rewritable memory effect, are observed in the flexible memory devices with the configuration of Al/1T@2H-MoS2 -polyvinylpyrrolidone (PVP)/indium tin oxide (ITO)/polyethylene terephthalate (PET) and Al/2H-MoS2 -PVP/ITO/PET, respectively. It is observed that structural phase transition in MoS2 nanosheets plays an important role on the resistive switching behaviors of the MoS2 -based device. It is hoped that our results can offer a general route for the preparation of various promising nanocomposites based on 2D nanosheets of layered transition metal dichalcogenides for fabricating the high performance and flexible nonvolatile memory devices through regulating the phase structure in the 2D nanosheets.

  17. Effects of drying temperature and ethanol concentration on bipolar switching characteristics of natural Aloe vera-based memory devices.

    Science.gov (United States)

    Lim, Zhe Xi; Cheong, Kuan Yew

    2015-10-28

    Extracted, formulated, and processed natural Aloe vera has been used as an active layer for memory applications. The functional memory device is realized by a bottom-up structure of ITO/Aloe vera/Al in which the Aloe vera is spin-coated after mixing with different concentrations of ethanol (0-80 wt%) and subsequently dried at different temperatures (50-120 °C). From the current density-voltage measurements, the device can exhibit a reproducible bipolar switching characteristic with pure Aloe vera dried at 50 °C. It is proposed that charges are transported across the Aloe vera layer via space-charge-limited conduction (SCLC), and clusters of interstitial space formed by the functional groups of acemannans and de-esterified pectins in the dried Aloe vera contribute to the memory effect. The formation of charge traps in the Aloe vera layer is dependent on the drying temperature. The drying temperature of a memory-switching Aloe vera layer can be extended to 120 °C with the addition of appropriate amounts of ethanol. The concept of using natural Aloe vera as an active material for memory applications has been demonstrated, and the read memory window, ON/OFF ratio, and retention time are approximately 5.0 V, 10(3), and >10(4) s, respectively.

  18. Suppression of thermoelectric Thomson effect in silicon microwires under large electrical bias and implications for phase-change memory devices

    Science.gov (United States)

    Bakan, Gokhan; Gokirmak, Ali; Silva, Helena

    2014-12-01

    We have observed how thermoelectric effects that result in asymmetric melting of silicon wires are suppressed for increasing electric current density (J). The experimental results are investigated using numerical modeling of the self-heating process, which elucidates the relative contributions of the asymmetric thermoelectric Thomson heat (˜J) and symmetric Joule heating (˜J2) that lead to symmetric heating for higher current levels. These results are applied in modeling of the self-heating process in phase-change memory devices. While, phase-change memory devices show a clearly preferred operation polarity due to thermoelectric effects, nearly symmetric operation can be achieved with higher amplitude and shorter current pulses, which can lead to design of improved polarity-invariant memory circuitry.

  19. High-performance and low-power rewritable SiOx 1 kbit one diode-one resistor crossbar memory array.

    Science.gov (United States)

    Wang, Gunuk; Lauchner, Adam C; Lin, Jian; Natelson, Douglas; Palem, Krishna V; Tour, James M

    2013-09-14

    An entire 1-kilobit crossbar device based upon SiOx resistive memories with integrated diodes has been made. The SiOx -based one diode-one resistor device system has promise to satisfy the prerequisite conditions for next generation non-volatile memory applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Parallel database search and prime factorization with magnonic holographic memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Khitun, Alexander [Electrical and Computer Engineering Department, University of California - Riverside, Riverside, California 92521 (United States)

    2015-12-28

    In this work, we describe the capabilities of Magnonic Holographic Memory (MHM) for parallel database search and prime factorization. MHM is a type of holographic device, which utilizes spin waves for data transfer and processing. Its operation is based on the correlation between the phases and the amplitudes of the input spin waves and the output inductive voltage. The input of MHM is provided by the phased array of spin wave generating elements allowing the producing of phase patterns of an arbitrary form. The latter makes it possible to code logic states into the phases of propagating waves and exploit wave superposition for parallel data processing. We present the results of numerical modeling illustrating parallel database search and prime factorization. The results of numerical simulations on the database search are in agreement with the available experimental data. The use of classical wave interference may results in a significant speedup over the conventional digital logic circuits in special task data processing (e.g., √n in database search). Potentially, magnonic holographic devices can be implemented as complementary logic units to digital processors. Physical limitations and technological constrains of the spin wave approach are also discussed.

  1. IVO, a device for In situ Volatilization and On-line detection of products from heavy ion reactions

    CERN Document Server

    Duellmann, C E; Eichler, R; Gäggeler, H W; Jost, D T; Piguet, D; Türler, A

    2002-01-01

    A new gaschromatographic separation system to rapidly isolate heavy ion reaction products in the form of highly volatile species is described. Reaction products recoiling from the target are stopped in a gas volume and converted in situ to volatile species, which are swept by the carrier gas to a chromatography column. Species that are volatile under the given conditions pass through the column. In a cluster chamber, which is directly attached to the exit of the column, the isolated volatile species are chemically adsorbed to the surface of aerosol particles and transported to an on-line detection system. The whole set-up was tested using short-lived osmium (Os) and mercury (Hg) nuclides produced in heavy ion reactions to model future chemical studies with hassium (Hs, Z=108) and element 112. By varying the temperature of the isothermal section of the chromatography column between room temperature and -80 deg. C, yield measurements of given species can be conducted, yielding information about the volatility o...

  2. Using volatile additives to alter the morphology and performance of active layers in thin-film molecular photovoltaic devices incorporating bulk heterojunctions.

    Science.gov (United States)

    Dang, Minh Trung; Wuest, James D

    2013-12-07

    Thin-film photovoltaic devices composed of polymers or small molecules have an exciting future as sources of renewable energy because they can be made in large sizes on flexible surfaces by inexpensive techniques of fabrication. Significant progress in developing new molecular photovoltaic materials and device architectures has been achieved in the last decade. The identity of molecular components in active layers and their individual optoelectronic properties obviously help determine the properties of devices; in addition, however, the behavior of devices depends critically on the nature of the local organization of the components. Recent studies have shown that the morphology of active layers can be tuned by adjusting various parameters, including the solvent used to cast the layer, thermal annealing, and special processing additives. In this review, we summarize the effect of volatile additives on the nanoscale morphology of molecular blends, and we show how these effects can improve the performance of devices. Although we focus on the behavior of mixtures of the type used in current molecular thin-film photovoltaic devices, the subject of our review will interest researchers in all areas of science and technology requiring materials in which separate phases must form intimate long-lived intermixtures with defined structures.

  3. 新型非易失相变存储器PCM应用研究%Application Research on New Non-Volatile Phase Change Memory PCM

    Institute of Scientific and Technical Information of China (English)

    刘金垒; 李琼

    2012-01-01

    Parallel I/O has optimized I/O performance effectively, but it is difficult to reduce the access latency. The Phase Change Memory, as a sort of SCM (Storage Class Memory), has distinct characters of non-volatile, randomly read and write, low latency, high throughput, small volume and low power consumption, it provides a direct and effective way for optimizing the I/O performance. In this paper, the PCM's characteristics and problems existed are studied, some research progress on PCM application are summarized. To solve parallel I/O problems, a hierachical parallel I/O storage model based on PCM is introduced, which can improve the efficiency on metadata service and the throughput of parallel I/O in parallel file system.%并行I/O技术有效优化了I/O性能,但对访问延迟却难以控制.相变存储器(phase change memory,PCM)作为一种SCM(storage class memory),具有非易失性、随机可读写、低延迟、高吞吐率、体积小和低功耗的特点,为I/O性能优化提供了最直接有效的途径.研究了PCM的特性与存在的问题,总结了目前PCM的应用研究进展,针对高性能计算中的并行I/O问题,提出了一种基于相变存储器PCM的层次式并行混合存储模型,能够有效提高并行文件系统元数据服务效率和并行I/O吞吐率.

  4. Organic nano-floating-gate transistor memory with metal nanoparticles

    Science.gov (United States)

    Van Tho, Luu; Baeg, Kang-Jun; Noh, Yong-Young

    2016-04-01

    Organic non-volatile memory is advanced topics for various soft electronics applications as lightweight, low-cost, flexible, and printable solid-state data storage media. As a key building block, organic field-effect transistors (OFETs) with a nano-floating gate are widely used and promising structures to store digital information stably in a memory cell. Different types of nano-floating-gates and their various synthesis methods have been developed and applied to fabricate nanoparticle-based non-volatile memory devices. In this review, recent advances in the classes of nano-floating-gate OFET memory devices using metal nanoparticles as charge-trapping sites are briefly reviewed. Details of device fabrication, characterization, and operation mechanisms are reported based on recent research activities reported in the literature.

  5. Four-state memory based on a giant and non-volatile converse magnetoelectric effect in FeAl/PIN-PMN-PT structure.

    Science.gov (United States)

    Wei, Yanping; Gao, Cunxu; Chen, Zhendong; Xi, Shibo; Shao, Weixia; Zhang, Peng; Chen, Guilin; Li, Jiangong

    2016-07-15

    We report a stable, tunable and non-volatile converse magnetoelectric effect (ME) in a new type of FeAl/PIN-PMN-PT heterostructure at room temperature, with a giant electrical modulation of magnetization for which the maximum relative magnetization change (ΔM/M) is up to 66%. The 109° ferroelastic domain switching in the PIN-PMN-PT and coupling with the ferromagnetic (FM) film via uniaxial anisotropy originating from the PIN-PMN-PT (011) surface are the key roles in converse ME effect. We also propose here a new, four-state memory through which it is possible to modify the remanent magnetism state by adjusting the electric field. This work represents a helpful approach to securing electric-writing magnetic-reading with low energy consumption for future high-density information storage applications.

  6. Four-state memory based on a giant and non-volatile converse magnetoelectric effect in FeAl/PIN-PMN-PT structure

    Science.gov (United States)

    Wei, Yanping; Gao, Cunxu; Chen, Zhendong; Xi, Shibo; Shao, Weixia; Zhang, Peng; Chen, Guilin; Li, Jiangong

    2016-07-01

    We report a stable, tunable and non-volatile converse magnetoelectric effect (ME) in a new type of FeAl/PIN-PMN-PT heterostructure at room temperature, with a giant electrical modulation of magnetization for which the maximum relative magnetization change (ΔM/M) is up to 66%. The 109° ferroelastic domain switching in the PIN-PMN-PT and coupling with the ferromagnetic (FM) film via uniaxial anisotropy originating from the PIN-PMN-PT (011) surface are the key roles in converse ME effect. We also propose here a new, four-state memory through which it is possible to modify the remanent magnetism state by adjusting the electric field. This work represents a helpful approach to securing electric-writing magnetic-reading with low energy consumption for future high-density information storage applications.

  7. Nonvolatile Resistance Random Access Memory Devices Based on ZnO Nanorod Arrays

    Directory of Open Access Journals (Sweden)

    Liang-Wen Ji

    2015-02-01

    Full Text Available In this paper, a nonvolatile resistance random access memory (RRAM device based on ZnO nanorod arrays has been fabricated and characterized. Vertically aligned ZnO nanorod layers (NRLs were deposited on indium tin oxide (ITO electrodes using a hydrothermal process/ chemical bath deposition (CBD. It can be found the Ag/ZnO NRL/ITO capacitor exhibits bipolar resistive switching behavior. The resistive switching behavior may be related to the oxygen vacancies and/or zinc interstitials confined on the surface of the ZnO NRs, giving rise to the formation of straight and extensible conducting path along each ZnO NR. Furthermore, superior stability in resistive switching characteristics was also observed. Both growing times and annealing times were investigated and annealing was done in oxygen for 3, 6 and 9 minutes at different temperatures. For ZnO nanorods that had been annealed for 6 minutes the forming voltage was about 6.06V, the Set voltage was about 3.25V and the Reset voltage was -2.78V. The original resistance was 7×106Ω. The resistance in the low-resistance state was 108Ω and in the high-resistance state was 2016Ω, the resistance ratio was 18.7.

  8. Treatment of ingrown nail with a special device composed of shape-memory alloy.

    Science.gov (United States)

    Park, Se-Won; Park, Ji-Ho; Lee, Jong-Hee; Lee, Dong-Youn; Lee, Joo-Heung; Yang, Jun-Mo

    2014-04-01

    Ingrown nail is a common nail problem resulting in pain and disability in daily life. Recently, a new treatment modality for an ingrown nail was reported that used a device composed of shape-memory alloy, K-D. The aim of the present study was to determine the efficacy, recurrence rate and complications of K-D. Between June 2010 and September 2012, 24 patients (31 nails) underwent treatment of symptomatic incurved nails with a K-D. Patients were evaluated at pretreatment and during every visit. The mean age of the patients involved was 43.4 years. The mean period of follow up was 161 days. The mean maintenance period was 41 days. The right first toenail was the most common site. Almost ingrown nails healed and the nail deformity was corrected after the procedure. Among the 31 nails, seven of the ingrown nails recurred during follow up (22.6% recurrence rate). The recurrence rate of the patients with stage 1, 2 and 3 ingrown nails was 22.2%, 33.3% and 14.2%, respectively. The majority of patients were very satisfied. There were no side-effects in most patients except loss of nail in one patient. K-D has some advantages such as simple application steps, no deformity after the procedure, high patient satisfaction and obvious effect compared to other non-invasive and invasive methods. © 2014 Japanese Dermatological Association.

  9. Nanoscale design of multifunctional organic layers for low-power high-density memory devices.

    Science.gov (United States)

    Nougaret, Laurianne; Kassa, Hailu G; Cai, Ronggang; Patois, Tilia; Nysten, Bernard; van Breemen, Albert J J M; Gelinck, Gerwin H; de Leeuw, Dago M; Marrani, Alessio; Hu, Zhijun; Jonas, Alain M

    2014-04-22

    We demonstrate the design of a multifunctional organic layer by the rational combination of nanosized regions of two functional polymers. Instead of relying on a spontaneous and random phase separation process or on the tedious synthesis of block copolymers, the method involves the nanomolding of a first component, followed by the filling of the resulting open spaces by a second component. We apply this methodology to fabricate organic nonvolatile memory diodes of high density. These are built by first creating a regular array of ferroelectric nanodots by nanoimprint lithography, followed by the filling of the trenches separating the ferroelectric nanodots with a semiconducting polymer. The modulation of the current in the semiconductor by the polarization state of the ferroelectric material is demonstrated both at the scale of a single semiconductor channel and in a microscopic device measuring about 80,000 channels in parallel, for voltages below ca. 2 V. The fabrication process, which combines synergetically orthogonal functional properties with a fine control over their spatial distribution, is thus demonstrated to be efficient over large areas.

  10. Can conventional phase-change memory devices be scaled down to single-nanometre dimensions?

    Science.gov (United States)

    Hayat, Hasan; Kohary, Krisztian; Wright, C. David

    2017-01-01

    The scaling potential of ‘mushroom-type’ phase-change memory devices is evaluated, down to single-nanometre dimensions, using physically realistic simulations that combine electro-thermal modelling with a Gillespie Cellular Automata phase-transformation approach. We found that cells with heater contact sizes as small as 6 nm could be successfully amorphized and re-crystallized (RESET and SET) using moderate excitation voltages. However, to enable the efficient formation of amorphous domes during RESET in small cells (heater contact diameters of 10 nm or less), it was necessary to improve the thermal confinement of the cell to reduce heat loss via the electrodes. The resistance window between the SET and RESET states decreased as the cell size reduced, but it was still more than an order of magnitude even for the smallest cells. As expected, the RESET current reduced as the cells got smaller; indeed, RESET current scaled with the inverse of the heater contact diameter and ultra-small RESET currents of only 19 μA were achieved for the smallest cells. Our results show that the conventional mushroom-type phase-change cell architecture is scalable and operable in the sub-10nm region.

  11. Management of long-term and reversible hysteroscopic sterilization: a novel device with nickel-titanium shape memory alloy.

    Science.gov (United States)

    Xu, Bin; Zhu, Ke-an; Xu, Dabao; Aili, Aixingzi

    2014-07-07

    Female sterilization is the second most commonly used method of contraception in the United States. Female sterilization can now be performed through laparoscopic, abdominal, or hysteroscopic approaches. The hysteroscopic sterilization may be a safer option than sterilization through laparoscopy or laparotomy because it avoids invading the abdominal cavity and undergoing general anaesthesia. Hysteroscopic sterilization mainly includes chemical agents and mechanical devices. Common issues related to the toxicity of the chemical agents used have raised concerns regarding this kind of contraception. The difficulty of the transcervical insertion of such mechanical devices into the fallopian tubes has increased the high incidence of device displacement or dislodgment. At present, Essure® is the only commercially available hysteroscopic sterilization device being used clinically. The system is irreversible and is not effective immediately. Our new hysteroscopic sterility system consists of nickel-titanium (NiTi) shape memory alloy and a waterproof membrane. The NiTi alloy is covered with two coatings to avoid toxic Ni release and to prevent stimulation of epithelial tissue growth around the oviducts. Because of the shape memory effect of the NiTi alloy, the device works like an umbrella: it stays collapsed at low temperature before placement and opens by the force of shape memory activated by the body temperature after it is inserted hysteroscopically into the interstitial tubal lumen. The rim of the open device will incise into interstitial myometrium during the process of unfolding. Once the device is fixed, it blocks the tube completely. When the patient no longer wishes for sterilization, the device can be closed by perfusing liquid with low temperature into the uterine cavity, followed by prospective hysteroscopic removal. After the device removal, the fallopian tube will revert to its physiological functions. Currently, experimental and clinical studies are needed

  12. Design and laboratory testing of a chamber device to measure total flux of volatile organic compounds from the unsaturated zone under natural conditions

    Science.gov (United States)

    Tillman, Fred D.; Smith, James A.

    2004-11-01

    To determine if an aquifer contaminated with volatile organic compounds (VOCs) has potential for natural remediation, all natural processes affecting the fate and transport of VOCs in the subsurface must be identified and quantified. This research addresses the quantification of air-phase volatile organic compounds (VOCs) leaving the unsaturated zone soil gas and entering the atmosphere—including the additional flux provided by advective soil-gas movement induced by barometric pumping. A simple and easy-to-use device for measuring VOC flux under natural conditions is presented. The vertical flux chamber (VFC) was designed using numerical simulations and evaluated in the laboratory. Mass-balance numerical simulations based on continuously stirred tank reactor equations (CSTR) provided information on flux measurement performance of several sampling configurations with the final chamber configuration measuring greater than 96% of model-simulated fluxes. A laboratory device was constructed to evaluate the flux chamber under both diffusion-only and advection-plus-diffusion transport conditions. The flux chamber measured an average of 82% of 15 diffusion-only fluxes and an average of 95% of 15 additional advection-plus-diffusion flux experiments. The vertical flux chamber has the capability of providing reliable measurement of VOC flux from the unsaturated zone under both diffusion and advection transport conditions.

  13. Electrical bistabilities and operating mechanisms of memory devices fabricated utilizing ZnO quantum dot-multi-walled carbon nanotube nanocomposites

    Science.gov (United States)

    Li, Fushan; Son, Dong Ick; Cho, Sung Hwan; Kim, Tae Whan

    2009-05-01

    Transmission electron microscopy images showed that the ZnO quantum dots (QDs) were conjugated with multi-walled carbon nanotubes (MWCNTs). Bistable memories utilizing an ensemble of the ZnO QD-MWCNT heterostructures were developed and the storage capability of the devices was significantly enhanced due to the conjugation of the ZnO QDs and the MWCNTs. Operating mechanisms of memory devices fabricated utilizing the ZnO QD-MWCNT heterostructures are described on the basis of the current-voltage results. The memory devices exhibited excellent environmental stability at ambient conditions.

  14. Modeling for Formation of Conducting Path in Cu/SiO2/Pt Memory Devices: Based on Soft Breakdown Mechanism

    Science.gov (United States)

    Luo, J. M.

    2013-09-01

    The forming process before resistive switching in Cu/ SiO2/Pt memory devices, corresponding to the formation of conducting path, can be regarded as the dielectric soft breakdown. Based on the analysis of breakdown mechanism, a dynamic model combining the transition of Cu ions with the space-charge effect has been proposed, and demonstrates that the forming voltage depends on the thickness of oxide, the sweep rate of voltage and temperature. The predictions of the model are consistent with the experiment data reported in the literature and it is believed that the transition of Cu ions across the oxide and the accumulation of Cu ions at the SiO2/Pt interface could be responsible for the conductive path formation in Cu/SiO2/Pt memory devices.

  15. Materials and Physics Challenges for Spin Transfer Torque Magnetic Random Access Memories

    Energy Technology Data Exchange (ETDEWEB)

    Heinonen, O.

    2014-10-05

    Magnetic random access memories utilizing the spin transfer torque effect for writing information are a strong contender for non-volatile memories scalable to the 20 nm node, and perhaps beyond. I will here examine how these devices behave as the device size is scaled down from 70 nm size to 20 nm. As device sizes go below ~50 nm, the size becomes comparable to intrinsic magnetic length scales and the device behavior does not simply scale with size. This has implications for the device design and puts additional constraints on the materials in the device.

  16. Endurance degradation and lifetime model of p-channel floating gate flash memory device with 2T structure

    Science.gov (United States)

    Wei, Jiaxing; Liu, Siyang; Liu, Xiaoqiang; Sun, Weifeng; Liu, Yuwei; Liu, Xiaohong; Hou, Bo

    2017-08-01

    The endurance degradation mechanisms of p-channel floating gate flash memory device with two-transistor (2T) structure are investigated in detail in this work. With the help of charge pumping (CP) measurements and Sentaurus TCAD simulations, the damages in the drain overlap region along the tunnel oxide interface caused by band-to-band (BTB) tunneling programming and the damages in the channel region resulted from Fowler-Nordheim (FN) tunneling erasure are verified respectively. Furthermore, the lifetime model of endurance characteristic is extracted, which can extrapolate the endurance degradation tendency and predict the lifetime of the device.

  17. The effect of the thickness of tunneling layer on the memory properties of (Cu2O)0.5(Al2O3)0.5 high-k composite charge-trapping memory devices

    Science.gov (United States)

    Liu, Jinqiu; Lu, Jianxin; Yin, Jiang; Xu, Bo; Xia, Yidong; Liu, Zhiguo

    2016-06-01

    The charge-trapping memory devices namely Pt/Al2O3/(Al2O3)0.5(Cu2O)0.5/SiO2/p-Si with 2, 3 and 4 nm SiO2 tunneling layers were fabricated by using RF magnetron sputtering and atomic layer deposition techniques. At an applied voltage of ±11 V, the memory windows in the C-V curves of the memory devices with 2, 3 and 4 nm SiO2 tunneling layers were about 4.18, 9.91 and 11.33 V, respectively. The anomaly in memory properties among the three memory devices was ascribed to the different back tunneling probabilities of trapped electrons in the charge-trapping dielectric (Al2O3)0.5(Cu2O)0.5 due to the different thicknesses of SiO2 tunneling layer.

  18. Matrix-dependent Strain Distributions of Au and Ag Nanoparticles in a Metal-oxide-semiconductor-based Nonvolatile Memory Device

    OpenAIRE

    Honghua Huang; Ying Zhang; Wenyan Wei; Ting Yu; Xingfang Luo; Cailei Yuan

    2015-01-01

    The matrix-dependent strain distributions of Au and Ag nanoparticles in a metal-oxide-semiconductor based nonvolatile memory device are investigated by finite element calculations. The simulation results clearly indicate that both Au and Ag nanoparticles incur compressive strain by high-k Al2O3 and conventional SiO2 dielectrics. The strain distribution of nanoparticles is closely related to the surrounding matrix. Nanoparticles embedded in different matrices experience different compressive s...

  19. A New Concept for Non-Volatile Memory: The Electric-Pulse Induced Resistive Change Effect in Colossal Magnetoresistive Thin Films

    Science.gov (United States)

    Liu, S. Q.; Wu, N. J.; Ignatiev, A.

    2001-01-01

    A novel electric pulse-induced resistive change (EPIR) effect has been found in thin film colossal magnetoresistive (CMR) materials, and has shown promise for the development of resistive, nonvolatile memory. The EPIR effect is induced by the application of low voltage (resistance of the thin film sample depending on pulse polarity. The sample resistance change has been shown to be over two orders of magnitude, and is nonvolatile after pulsing. The sample resistance can also be changed through multiple levels - as many as 50 have been shown. Such a device can provide a way for the development of a new kind of nonvolatile multiple-valued memory with high density, fast write/read speed, low power-consumption, and potential high radiation-hardness.

  20. Metal induced crystallized poly-Si-based conductive bridge resistive switching memory device with one transistor and one resistor architecture

    Science.gov (United States)

    Chand, Umesh; Huang, Chun-Yang; Kumar, Dayanand; Tseng, Tseung-Yuen

    2015-11-01

    In this letter, the metal induced crystallization (MIC) process is used in the Si-based conductive bridging resistive random access memory (CBRAM) application. The amorphous Si (a-Si) is transformed to crystallized poly-silicon (poly-Si) at a low temperature by using Ni metal for inducing poly-Si to provide the resistive switching. The MIC process can produce a highly preferred orientation poly-Si film, which can create the exact paths or grain boundaries through the top and down electrodes in the present CBRAM device. The grain boundary in MIC poly-Si layer can confine the conductive filament of metal bridging growth in it, which can improve the switching fluctuation behavior in the nonvolatile memory application. Compared with the a-Si based device, a significant improvement in terms of resistive switching parameters such as stability and resistance distribution is demonstrated in the MIC poly-Si CBRAM device. Moreover, the well-behaved memory performance, such as high ON/OFF resistance ratio (4 order), a large AC endurance (106), and good retention characteristics (104 s at 125 °C) are achieved in the Cu/poly-Si/n+-Si CMOS compatible cross bar structure.

  1. Giant magneto-resistance devices

    CERN Document Server

    Hirota, Eiichi; Inomata, Koichiro

    2002-01-01

    This book deals with the application of giant magneto-resistance (GMR) effects to electronic devices. It will appeal to engineers and graduate students in the fields of electronic devices and materials. The main subjects are magnetic sensors with high resolution and magnetic read heads with high sensitivity, required for hard-disk drives with recording densities of several gigabytes. Another important subject is novel magnetic random-access memories (MRAM) with non-volatile non-destructive and radiation-resistant characteristics. Other topics include future GMR devices based on bipolar spin transistors, spin field-effect transistors (FETs) and double-tunnel junctions.

  2. Towards developing a compact model for magnetization switching in straintronics magnetic random access memory devices

    Science.gov (United States)

    Barangi, Mahmood; Erementchouk, Mikhail; Mazumder, Pinaki

    2016-08-01

    Strain-mediated magnetization switching in a magnetic tunneling junction (MTJ) by exploiting a combination of piezoelectricity and magnetostriction has been proposed as an energy efficient alternative to spin transfer torque (STT) and field induced magnetization switching methods in MTJ-based magnetic random access memories (MRAM). Theoretical studies have shown the inherent advantages of strain-assisted switching, and the dynamic response of the magnetization has been modeled using the Landau-Lifshitz-Gilbert (LLG) equation. However, an attempt to use LLG for simulating dynamics of individual elements in large-scale simulations of multi-megabyte straintronics MRAM leads to extremely time-consuming calculations. Hence, a compact analytical solution, predicting the flipping delay of the magnetization vector in the nanomagnet under stress, combined with a liberal approximation of the LLG dynamics in the straintronics MTJ, can lead to a simplified model of the device suited for fast large-scale simulations of multi-megabyte straintronics MRAMs. In this work, a tensor-based approach is developed to study the dynamic behavior of the stressed nanomagnet. First, using the developed method, the effect of stress on the switching behavior of the magnetization is investigated to realize the margins between the underdamped and overdamped regimes. The latter helps the designer realize the oscillatory behavior of the magnetization when settling along the minor axis, and the dependency of oscillations on the stress level and the damping factor. Next, a theoretical model to predict the flipping delay of the magnetization vector is developed and tested against LLG-based numerical simulations to confirm the accuracy of findings. Lastly, the obtained delay is incorporated into the approximate solutions of the LLG dynamics, in order to create a compact model to liberally and quickly simulate the magnetization dynamics of the MTJ under stress. Using the developed delay equation, the

  3. Towards developing a compact model for magnetization switching in straintronics magnetic random access memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Barangi, Mahmood, E-mail: barangi@umich.edu; Erementchouk, Mikhail; Mazumder, Pinaki [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2121 (United States)

    2016-08-21

    Strain-mediated magnetization switching in a magnetic tunneling junction (MTJ) by exploiting a combination of piezoelectricity and magnetostriction has been proposed as an energy efficient alternative to spin transfer torque (STT) and field induced magnetization switching methods in MTJ-based magnetic random access memories (MRAM). Theoretical studies have shown the inherent advantages of strain-assisted switching, and the dynamic response of the magnetization has been modeled using the Landau-Lifshitz-Gilbert (LLG) equation. However, an attempt to use LLG for simulating dynamics of individual elements in large-scale simulations of multi-megabyte straintronics MRAM leads to extremely time-consuming calculations. Hence, a compact analytical solution, predicting the flipping delay of the magnetization vector in the nanomagnet under stress, combined with a liberal approximation of the LLG dynamics in the straintronics MTJ, can lead to a simplified model of the device suited for fast large-scale simulations of multi-megabyte straintronics MRAMs. In this work, a tensor-based approach is developed to study the dynamic behavior of the stressed nanomagnet. First, using the developed method, the effect of stress on the switching behavior of the magnetization is investigated to realize the margins between the underdamped and overdamped regimes. The latter helps the designer realize the oscillatory behavior of the magnetization when settling along the minor axis, and the dependency of oscillations on the stress level and the damping factor. Next, a theoretical model to predict the flipping delay of the magnetization vector is developed and tested against LLG-based numerical simulations to confirm the accuracy of findings. Lastly, the obtained delay is incorporated into the approximate solutions of the LLG dynamics, in order to create a compact model to liberally and quickly simulate the magnetization dynamics of the MTJ under stress. Using the developed delay equation, the

  4. Enhanced non-volatile memory characteristics with quattro-layer graphene nanoplatelets vs . 2.85-nm Si nanoparticles with asymmetric Al2O3/HfO2 tunnel oxide

    Science.gov (United States)

    El-Atab, Nazek; Turgut, Berk Berkan; Okyay, Ali K.; Nayfeh, Munir; Nayfeh, Ammar

    2015-06-01

    In this work, we demonstrate a non-volatile metal-oxide semiconductor (MOS) memory with Quattro-layer graphene nanoplatelets as charge storage layer with asymmetric Al2O3/HfO2 tunnel oxide and we compare it to the same memory structure with 2.85-nm Si nanoparticles charge trapping layer. The results show that graphene nanoplatelets with Al2O3/HfO2 tunnel oxide allow for larger memory windows at the same operating voltages, enhanced retention, and endurance characteristics. The measurements are further confirmed by plotting the energy band diagram of the structures, calculating the quantum tunneling probabilities, and analyzing the charge transport mechanism. Also, the required program time of the memory with ultra-thin asymmetric Al2O3/HfO2 tunnel oxide with graphene nanoplatelets storage layer is calculated under Fowler-Nordheim tunneling regime and found to be 4.1 ns making it the fastest fully programmed MOS memory due to the observed pure electrons storage in the graphene nanoplatelets. With Si nanoparticles, however, the program time is larger due to the mixed charge storage. The results confirm that band-engineering of both tunnel oxide and charge trapping layer is required to enhance the current non-volatile memory characteristics.

  5. Development of a novel shape memory alloy-actuated resettable locking device for magnetic bearing reaction wheel.

    Science.gov (United States)

    Zhang, Xiaoyong; Yan, Xiaojun; Zhang, Shaowei; Nie, Jingxu

    2014-01-01

    The current investigation proposes a shape memory alloy (SMA)-actuated resettable locking device for magnetic bearing reaction wheel. The device employed two SMA wire-based actuators to realize locking and unlocking. Dual-slope mating surfaces were used on one hand to transmit the motion between a moving part and a clamp, and on the other hand to achieve a self-locking linkage in the locking state. Moreover, geometric parameters of the two SMA wires and corresponding bias springs were also designed. Based on the proposed design scheme, four locking devices were manufactured and assembled. Performance and environmental tests were performed to verify the proposed locking device. Test results show that the locking device can protect the magnetic bearing reaction wheel from launch vibration damage, and can withstand the thermal environment in the launch and on-orbit stage. Moreover, the device can be successfully operated for 76 times, and the response time for the locking and unlocking processes under 7 V power supply is 0.9 s and 5.6 s, respectively. Considering the results obtained from these tests, we conclude that the proposed resettable locking device is an attractive alternative technology to conventional motor-driven or pyrotechnics-based technologies, and can be applied reliably in the magnetic bearing reaction wheel.

  6. Atomic-scale quantification of interdiffusion and dopant localization in GeSbTe-based memory devices

    Science.gov (United States)

    Chae, B.-G.; Seol, J.-B.; Song, J.-H.; Jung, W.-Y.; Hwang, H.; Park, C.-G.

    2016-09-01

    Fabrication of phase-change memory devices at modest or ambient temperatures leads to nanoscale compositional variations in phase-transition layers, where amorphous-polycrystalline phase change takes place via electrical switching, and can alter the device's performances. Here, by transmission electron microscopy and atom probe tomography, we address that thermal annealing at 400 °C for 20 min induces an elemental interdiffusion in the devices consisting of TiN (top electrode), carbon-doped GeSbTe (phase-transition layer), and TiSiN (bottom heater). With respect to the employed annealing process, the Ge atoms of GeSbTe layer have diffused into TiSiN layer at a given sample volume, while the Ti atoms of TiSiN layer into GeSbTe layer. Furthermore, non-random nature of dopant distribution in the GeSbTe materials leads to a Ti-localization including dopants at the GeSbTe/TiSiN interfaces. Our findings have two important implications: First, the annealing-driven interdiffusion of Ge and Ti is a predominant mechanism responsible for nanoscale compositional variations in GeSbTe layer; second, such an interdiffusion and the resultant dopant localization play a crucial role on the driving force for amorphous-polycrystalline transition of GeSbTe-based memory devices.

  7. Nonvolatile Memory Technology for Space Applications

    Science.gov (United States)

    Oldham, Timothy R.; Irom, Farokh; Friendlich, Mark; Nguyen, Duc; Kim, Hak; Berg, Melanie; LaBel, Kenneth A.

    2010-01-01

    This slide presentation reviews several forms of nonvolatile memory for use in space applications. The intent is to: (1) Determine inherent radiation tolerance and sensitivities, (2) Identify challenges for future radiation hardening efforts, (3) Investigate new failure modes and effects, and technology modeling programs. Testing includes total dose, single event (proton, laser, heavy ion), and proton damage (where appropriate). Test vehicles are expected to be a variety of non-volatile memory devices as available including Flash (NAND and NOR), Charge Trap, Nanocrystal Flash, Magnetic Memory (MRAM), Phase Change--Chalcogenide, (CRAM), Ferroelectric (FRAM), CNT, and Resistive RAM.

  8. SEMICONDUCTOR DEVICES Novel multi-bit non-uniform channel charge trapping memory device with virtual-source NAND flash array

    Science.gov (United States)

    Haiming, Gu; Liyang, Pan; Peng, Zhu; Dong, Wu; Zhigang, Zhang; Jun, Xu

    2010-10-01

    In order to overcome the bit-to-bit interference of the traditional multi-level NAND type device, this paper firstly proposes a novel multi-bit non-uniform channel charge trapping memory (NUC-CTM) device with virtual-source NAND-type array architecture, which can effectively restrain the second-bit effect (SBE) and provide 3-bit per cell capability. Owing to the n- buffer region, the SBE induced threshold voltage window shift can be reduced to less than 400 mV and the minimum threshold voltage window between neighboring levels is larger than 750 mV for reliable 3-bit operation. A silicon-rich SiON is also investigated as a trapping layer to improve the retention reliability of the NUC-CTM.

  9. 3D Printing of Shape Memory Polymers for Flexible Electronic Devices.

    Science.gov (United States)

    Zarek, Matt; Layani, Michael; Cooperstein, Ido; Sachyani, Ela; Cohn, Daniel; Magdassi, Shlomo

    2016-06-01

    The formation of 3D objects composed of shape memory polymers for flexible electronics is described. Layer-by-layer photopolymerization of methacrylated semicrystalline molten macromonomers by a 3D digital light processing printer enables rapid fabrication of complex objects and imparts shape memory functionality for electrical circuits.

  10. Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices.

    Science.gov (United States)

    Grosse, Kyle L; Pop, Eric; King, William P

    2014-09-01

    This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K(-1). This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

  11. Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Grosse, Kyle L. [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Pop, Eric [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); King, William P., E-mail: wpk@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Departments of Electrical and Computer Engineering and Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    2014-09-15

    This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K{sup −1}. This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

  12. Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices

    Science.gov (United States)

    Grosse, Kyle L.; Pop, Eric; King, William P.

    2014-09-01

    This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K-1. This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

  13. Organic ferroelectric/semiconducting nanowire hybrid layer for memory storage

    NARCIS (Netherlands)

    Cai, R.; Kassa, H.G.; Haouari, R.; Marrani, A.; Geerts, Y.H.; Ruzié, C.; Breemen, A.J.J.M. van; Gelinck, G.H.; Nysten, B.; Hu, Z.; Jonas, A.M.

    2016-01-01

    Ferroelectric materials are important components of sensors, actuators and non-volatile memories. However, possible device configurations are limited due to the need to provide screening charges to ferroelectric interfaces to avoid depolarization. Here we show that, by alternating ferroelectric and

  14. Nonvolatile and Cryogenic-compatible Quantum Memory Devices (QuMEM)

    Science.gov (United States)

    2016-06-01

    15 3.9 MRAM ...PCs) Volatile Resistive RAM s 0.5−2.0 V High to low Research and development (R&D) Speed, voltage, sensitivity, endurance MRAM 100 ps− ns...due to the material system it utilizes. 3.9 MRAM There are limitations on the overall scalability (>25 to 30 nm) and technology integration with

  15. Magnetic Random Access Memory based non-volatile asynchronous Muller cell for ultra-low power autonomous applications

    Science.gov (United States)

    Di Pendina, G.; Zianbetov, E.; Beigne, E.

    2015-05-01

    Micro and nano electronic integrated circuit domain is today mainly driven by the advent of the Internet of Things for which the constraints are strong, especially in terms of power consumption and autonomy, not only during the computing phases but also during the standby or idle phases. In such ultra-low power applications, the circuit has to meet new constraints mainly linked to its changing energetic environment: long idle phases, automatic wake up, data back-up when the circuit is sporadically turned off, and ultra-low voltage power supply operation. Such circuits have to be completely autonomous regarding their unstable environment, while remaining in an optimum energetic configuration. Therefore, we propose in this paper the first MRAM-based non-volatile asynchronous Muller cell. This cell has been simulated and characterized in a very advanced 28 nm CMOS fully depleted silicon-on-insulator technology, presenting good power performance results due to an extremely efficient body biasing control together with ultra-wide supply voltage range from 160 mV up to 920 mV. The leakage current can be reduced to 154 pA thanks to reverse body biasing. We also propose an efficient standard CMOS bulk version of this cell in order to be compatible with different fabrication processes.

  16. Magnetic Random Access Memory based non-volatile asynchronous Muller cell for ultra-low power autonomous applications

    Energy Technology Data Exchange (ETDEWEB)

    Di Pendina, G., E-mail: gregory.dipendina@cea.fr, E-mail: eldar.zianbetov@cea.fr, E-mail: edith.beigne@cea.fr; Zianbetov, E., E-mail: gregory.dipendina@cea.fr, E-mail: eldar.zianbetov@cea.fr, E-mail: edith.beigne@cea.fr [Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble (France); CNRS, SPINTEC, F-38000 Grenoble (France); CEA, INAC-SPINTEC, F-38000 Grenoble (France); Beigne, E., E-mail: gregory.dipendina@cea.fr, E-mail: eldar.zianbetov@cea.fr, E-mail: edith.beigne@cea.fr [Univ. Grenoble Alpes, CEA, LETI, F-38000 Grenoble (France)

    2015-05-07

    Micro and nano electronic integrated circuit domain is today mainly driven by the advent of the Internet of Things for which the constraints are strong, especially in terms of power consumption and autonomy, not only during the computing phases but also during the standby or idle phases. In such ultra-low power applications, the circuit has to meet new constraints mainly linked to its changing energetic environment: long idle phases, automatic wake up, data back-up when the circuit is sporadically turned off, and ultra-low voltage power supply operation. Such circuits have to be completely autonomous regarding their unstable environment, while remaining in an optimum energetic configuration. Therefore, we propose in this paper the first MRAM-based non-volatile asynchronous Muller cell. This cell has been simulated and characterized in a very advanced 28 nm CMOS fully depleted silicon-on-insulator technology, presenting good power performance results due to an extremely efficient body biasing control together with ultra-wide supply voltage range from 160 mV up to 920 mV. The leakage current can be reduced to 154 pA thanks to reverse body biasing. We also propose an efficient standard CMOS bulk version of this cell in order to be compatible with different fabrication processes.

  17. Nonvolatile memory devices based on ZnO/polyimide nanocomposite sandwiched between two C{sub 60} layers

    Energy Technology Data Exchange (ETDEWEB)

    Li Fushan [Advanced Semiconductor Research Center, Division of Electronics and Computer Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Tae Whan, E-mail: twk@hanyang.ac.k [Advanced Semiconductor Research Center, Division of Electronics and Computer Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Dong Wenguo; Kim, Young-Ho [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2009-05-29

    The memory effects of a three-layer nonvolatile memory device Al/C{sub 60}/ZnO nanoparticles embedded in a polyimide (PI) layer/C{sub 60}/p-Si were investigated by using capacitance-voltage (C-V) measurements. Transmission electron microscopy and selected area electron diffraction pattern measurements showed that ZnO nanocrystals were formed inside the PI layer. The insertion of C{sub 60} layer improved the charge trap state density in the ZnO nanoparticle. The density was estimated by the flatband voltage shift in the C-V hysteresis, which increases with the max sweep voltage. Possible operating mechanisms corresponding to the charging and discharging process in the structure are proposed on the basis of the C-V results.

  18. Preparation of MoS₂-polyvinylpyrrolidone nanocomposites for flexible nonvolatile rewritable memory devices with reduced graphene oxide electrodes.

    Science.gov (United States)

    Liu, Juqing; Zeng, Zhiyuan; Cao, Xiehong; Lu, Gang; Wang, Lian-Hui; Fan, Qu-Li; Huang, Wei; Zhang, Hua

    2012-11-19

    A facile method for exfoliation and dispersion of molybdenum disulfide (MoS2) with the aid of polyvinylpyrrolidone (PVP) is proposed. The resultant PVP-coated MoS2 nanosheets, i.e., MoS2-PVP nanocomposites, are well dispersed in the low-boiling ethanol solvent, facilitating their thin film preparation and the device fabrication by solution processing technique. As a proof of concept, a flexible memory diode with the configuration of reduced graphene oxide (rGO)/MoS2-PVP/Al exhibited a typical bistable electrical switching and nonvolatile rewritable memory effect with the function of flash. These experimental results prove that the electrical transition is due to the charge trapping and detrapping behavior of MoS2 in the PVP dielectric material. This study paves a way of employing two-dimensional nanomaterials as both functional materials and conducting electrodes for the future flexible data storage.

  19. Oxygen-doped zirconium nitride based transparent resistive random access memory devices fabricated by radio frequency sputtering method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hee-Dong, E-mail: khd0708@sejong.ac.kr [Department of Electrical Engineering, Sejong University, Neungdong-ro 209, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Yun, Min Ju [Department of Electrical Engineering, Sejong University, Neungdong-ro 209, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Kim, Kyeong Heon [School of Electrical Engineering, Korea University, Anam-dong, Sungbuk-gu, Seoul 163-701 (Korea, Republic of); Kim, Sungho, E-mail: sungho85.kim@sejong.ac.kr [Department of Electrical Engineering, Sejong University, Neungdong-ro 209, Gwangjin-gu, Seoul 143-747 (Korea, Republic of)

    2016-08-05

    In this work, we present a feasibility of bipolar resistive switching (RS) characteristics for Oxygen-doped zirconium nitride (O-doped ZrN{sub x}) films, produced by sputtering method, which shows a high optical transmittance of approximately 78% in the visible region as well as near ultra-violet region. In addition, in a RS test, the device has a large current ratio of 5 × 10{sup 3} in positive bias region and 5 × 10{sup 5} in negative bias region. Then, to evaluate an ability of data storage for the proposed memory devices, we measured a retention time for 10{sup 4} s at room temperature (RT) and 85 °C as well. As a result, the set and reset states were stably maintained with a current ratio of ∼10{sup 2} at 85 °C to ∼10{sup 3} at RT. This result means that the transparent memory by controlling the working pressure during sputtering process to deposit the ZrN{sub x} films could be a milestone for future see-through electronic devices. - Highlights: • The resistive switching characteristics of the transparent O-doped ZrN{sub x}-based RRAM cells have investigated. • Oxygen doping concentration within ZrN{sub x} is optimized using working pressure of sputter. • Long retention time were observed.

  20. Structural design of a newly developed pediatric circulatory assist device for Fontan circulation by using shape memory alloy fiber.

    Science.gov (United States)

    Shiraishi, Y; Sugai, T K; Tanaka, A; Yoshizawa, M; Yambe, T; Yamada, A; Omran, M H; Shiga, T; Kitano, T; Kamiya, K; Mochizuki, S; Miura, H; Homma, D; Yamagishi, M

    2011-01-01

    Total cavopulmonary connection (TCPC) is commonly applied for the surgical treatment of congenital heart disease such as single ventricle in pediatric patients. Patients with no ventricle in pulmonary circulation are treated along with Fontan algorithm, in which the systemic venous return is diverted directly to the pulmonary artery without passing through subpulmonary ventricle. In order to promote the pulmonary circulation after Fontan procedure, we developed a newly designed pulmonary circulatory assist device by using shape memory alloy fibers. We developed a pulmonary circulatory assist device as a non-blood contacting mechanical support system in pediatric patients with TCPC. The device has been designed to be installed like a cuff around the ePTFE TCPC conduit, which can contract from outside. We employed a covalent type functional anisotropic shape memory alloy fiber (Biometal, Toki Corporation, Tokyo Japan) as a servo actuator of the pulmonary circulatory assist device. The diameter of this fiber was 100 microns, and its contractile frequency was 2-3 Hz. Heat generation with electric current contracts these fibers and the conduit. The maximum contraction ratio of this fiber is about 7% in length. In order to extend its contractile ratio, we fabricated and installed mechanical structural units to control the length of fibers. In this study, we examined basic contractile functions of the device in the mock system. As a result, the internal pressure of the conduit increased to 63 mmHg by the mechanical contraction under the condition of 400 msec-current supply in the mock examination with the overflow tank of 10 mmHg loading.

  1. Feasibility study of using a Zener diode as the selection device for bipolar RRAM and WORM memory arrays

    Science.gov (United States)

    Li, Yingtao; Fu, Liping; Tao, Chunlan; Jiang, Xinyu; Sun, Pengxiao

    2014-01-01

    Cross-bar arrays are usually used for the high density application of resistive random access memory (RRAM) devices. However, cross-talk interference limits an increase in the integration density. In this paper, the Zener diode is proposed as a selection device to suppress the sneak current in bipolar RRAM arrays. Measurement results show that the Zener diode can act as a good selection device, and the sneak current can be effectively suppressed. The readout margin is sufficiently improved compared to that obtained without the selection device. Due to the improvement for the reading disturbance, the size of the cross-bar array can be enhanced to more than 103 × 103. Furthermore, the possibility of using a write-once-read-many-times (WORM) cross-bar array is also demonstrated by connecting the Zener diode and the bipolar RRAM in series. These results strongly suggest that using a Zener diode as a selection device opens up great opportunities to realize high density bipolar RRAM arrays.

  2. 3D Printing: 3D Printing of Shape Memory Polymers for Flexible Electronic Devices (Adv. Mater. 22/2016).

    Science.gov (United States)

    Zarek, Matt; Layani, Michael; Cooperstein, Ido; Sachyani, Ela; Cohn, Daniel; Magdassi, Shlomo

    2016-06-01

    On page 4449, D. Cohn, S. Magdassi, and co-workers describe a general and facile method based on 3D printing of methacrylated macromonomers to fabricate shape-memory objects that can be used in flexible and responsive electrical circuits. Such responsive objects can be used in the fabrication of soft robotics, minimal invasive medical devices, sensors, and wearable electronics. The use of 3D printing overcomes the poor processing characteristics of thermosets and enables complex geometries that are not easily accessible by other techniques.

  3. Durability of rewritable phase-change Ge$_{X}$Sb$_{Y}$ Te$_{1−X−Y}$ memory devices

    Indian Academy of Sciences (India)

    N Parvathala Reddy; Ch Bapanayya; Rajeev Gupta; S C Agarwal

    2013-06-01

    The bond constraint theory (BCT) dealing with the rigidity caused by bond constraints and the long-range potential fluctuations (LRPF) arising from the defects and heterogeneities in the disordered semiconductors are important for understanding the atomic and electronic properties of amorphous semiconductors. Here, they are applied to the already commercialized Ge$_{X}$Sb$_{Y}$ Te$_{1−X−Y}$ (GST) chalcogenide glasses used in the rewritable phase change memory (PCM) devices. The main concern at present is to improve their ability to withstand a large number of phase change cycles, by choosing the right composition. The two considerations (BCT and LRPF) are briefly described and tested on the most commonly used Ge2Sb2Te5 and the nearby compositions. While these considerations provide significant insight into their atomic and electronic structures, the ansatz linking them with the durability of the PCM devices need to be justified by more work.

  4. Influence of Cu diffusion conditions on the switching of Cu-SiO{sub 2}-based resistive memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Thermadam, S. Puthen, E-mail: spchandr@asu.ed [Center for Applied Nanoionics, Arizona State University, Tempe, AZ 85287-6206 (United States); Bhagat, S.K.; Alford, T.L. [School of Materials, Arizona State University, Tempe AZ 85287-8706 (United States); Sakaguchi, Y. [Department of Electrical and Computer Engineering, Boise State University, Boise, ID 83725-2075 (United States); Kozicki, M.N. [Center for Applied Nanoionics, Arizona State University, Tempe, AZ 85287-6206 (United States); Mitkova, M. [Department of Electrical and Computer Engineering, Boise State University, Boise, ID 83725-2075 (United States)

    2010-04-02

    This paper presents a study of Cu diffusion at various temperatures in thin SiO{sub 2} films and the influence of diffusion conditions on the switching of Programmable Metallization Cell (PMC) devices formed from such Cu-doped films. Film composition and diffusion products were analyzed using secondary ion mass spectroscopy, Rutherford backscattering spectrometry, X-ray diffraction and Raman spectroscopy methods. We found a strong dependence of the diffused Cu concentration, which varied between 0.8 at.% and 10{sup -3} at.%, on the annealing temperature. X-ray diffraction and Raman studies revealed that Cu does not react with the SiO{sub 2} network and remains in elemental form after diffusion for the annealing conditions used. PMC resistive memory cells were fabricated with such Cu-diffused SiO{sub 2} films and device performance, including the stability of the switching voltage, is discussed in the context of the material characteristics.

  5. A nonvolatile memory device with very low power consumption based on the switching of a standard electrode potential

    Directory of Open Access Journals (Sweden)

    Issei Sugiyama

    2017-04-01

    Full Text Available We prepared a nonvolatile memory device that could be reversibly switched between a high and a low open-circuit voltage (Voc regime. The device is composed of a solid electrolyte Li3PO4 film sandwiched between metal Li and Au electrodes: a Li/Li3PO4/Au heterostructure, which was fabricated at room temperature on a glass substrate. The bistable states at Voc ∼ 0.7 and ∼0.3 V could be reversibly switched by applying an external voltage of 2.0 and 0.18 V, respectively. The formation and deformation of an ultrathin Au–Li alloy at the Li3PO4/Au electrode interface were the origin of the reversible switching.

  6. Level Shifts in Volatility and the Implied-Realized Volatility Relation

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper; de Magistris, Paolo Santucci

    to the multivariate case of the univariate level shift technique by Lu and Perron (2008). An application to the S&P500 index and a simulation experiment show that the recently documented empirical properties of strong persistence in volatility and forecastability of future realized volatility from current implied...... volatility, which have been interpreted as long memory (or fractional integration) in volatility and fractional cointegration between implied and realized volatility, are accounted for by occasional common level shifts....

  7. Radiation Testing, Characterization and Qualification Challenges for Modern Microelectronics and Photonics Devices and Technologies

    Science.gov (United States)

    LaBel, Kenneth A.; Cohn, Lewis M.

    2008-01-01

    At GOMAC 2007, we discussed a selection of the challenges for radiation testing of modern semiconductor devices focusing on state-of-the-art memory technologies. This included FLASH non-volatile memories (NVMs) and synchronous dynamic random access memories (SDRAMs). In this presentation, we extend this discussion in device packaging and complexity as well as single event upset (SEU) mechanisms using several technology areas as examples including: system-on-a-chip (SOC) devices and photonic or fiber optic systems. The underlying goal is intended to provoke thought for understanding the limitations and interpretation of radiation testing results.

  8. Experimental Validation of Condition Monitoring for Electrically Activated Shape Memory Alloys for an Unlocking Device

    Science.gov (United States)

    Rathmann, Christian; Theren, Benedict; Fleczok, Benjamin; Kuhlenkötter, Bernd

    2017-06-01

    Shape memory alloys (SMA) belong to the group functional materials which can be activated thermally. Along with a phase transformation, they can remember a previously imprinted shape and have a special resistance behavior. Therefore, they can also be used as a sensor and may be capable of detecting various system states in technical systems. This paper makes a contribution by evaluating the measurability of measured variables by SMA elements. Furthermore, it investigates the technically relevant states of “blockade” and “activation” of electrically activated shape memory actuators. It develops and validates an algorithm which is able to detect a possible “blockade”. Moreover, this work presents a hardware concept for a condition monitoring system of shape memory actuators.

  9. A low temperature processed Si-quantum-dot poly-Si TFT nonvolatile memory device

    Institute of Scientific and Technical Information of China (English)

    Sun Wei

    2013-01-01

    This paper reports on a successful demonstration of poly-Si TFT nonvolatile memory with a much reduced thermal-budget.The TFT uses uniform Si quantum-dots (size ~10 nm and density ~1011 cm-2) asstorage media,obtained via LPCVD by flashing SiH4/H2 at 580 ℃ for 15 s on a Si3N4 surface.The poly-Si grain-enlargement step was shifted after source/drain formation.The NiSix-silicided source/drain enables a fast lateral-recrystallization,and thus grain-enlargement can be accomplished by a much reduced thermal-cycle (i.e.,550 ℃/4 h).The excellent memory characteristics suggest that the proposed poly-Si TFT Si quantum-dot memory and associated processes are promising for use in wider TFT applications,such as system-on-glass.

  10. A Survey on Security and Privacy of Emerging Non-Volatile Memory%新型非易失存储的安全与隐私问题研究综述

    Institute of Scientific and Technical Information of China (English)

    徐远超; 闫俊峰; 万虎; 孙凤芸; 张伟功; 李涛

    2016-01-01

    In recent years ,emerging non‐volatile memory (NVM ) technologies ,such as phase change memory (PCM ) ,spin‐transfer torque RAM (ST T‐RAM ) ,and memristor have gained great attention of researchers .NVM has both byte‐addressable and non‐volatile features ,thereby making it possible to replace both traditional main memory and persistent storage .Also ,NVM can be used in hybrid memory and storage architecture .Due to the advantages of low latency ,high density ,and low power , NVM has become the promising memory technology because of the effect of alleviating memory wall problem .However ,applications can access NVM directly through ordinary load/store interface ,and more important , data resided in the NVM still retains after power loss , thus it imposes new challenges of security and privacy . This paper surveys several security problems about NVM and existing solutions including persistent memory leak , stray writes , metadata security , malicious wearout attacks ,and non‐volatile pointer . Then ,privacy issues and existing studies about NVM , such as data protection and information leaks , are discussed . Finally , we explore other potential security and privacy issues related to NVM and propose several possible solutions , such as convergence of permission and protection ,security of non‐volatile cache ,volatile NVM ,and program security .%近年来,以相变存储器(phase change memory ,PCM )为代表的各种新型非易失存储(non‐volatile memory ,NVM )技术得到广泛关注.NVM 同时具有传统内存的字节寻址特性和外存的非易失特性,因而可以同时替代内存和外存,也可以用于混合存储体系结构.NVM 具有低延时、高密度、低功耗的优势,有效缓解了存储墙问题.然而,由于应用程序可以直接通过存取指令(load/store)接口访问NVM ,并且掉电后存储在 NVM 上的信息不会丢失,这给 NVM 的应用带来了一些新的安全和隐私

  11. 柔性有机非易失性场效应晶体管存储器的研究进展%Progress of flexible organic non-volatile memory field-effect transistors

    Institute of Scientific and Technical Information of China (English)

    柴玉华; 郭玉秀; 卞伟; 李雯; 杨涛; 仪明东; 范曲立; 解令海; 黄维

    2014-01-01

    柔性有机非易失性场效应晶体管存储器具有柔性、质轻、成本低、可低温及大面积加工等优点,在射频识别标签、柔性存储、柔性集成电路和大面积柔性显示等领域展现出巨大的应用前景。本文在介绍柔性有机非易失性场效应晶体管存储器的衬底材料、器件结构和性能参数的基础上,总结了柔性有机非易失性场效应晶体管存储器的分类,并讨论了机械应力和不同温度对柔性有机非易失性场效应晶体管存储器性能参数的影响,最后展望了柔性有机非易失性场效应晶体管存储器的应用前景以及所面临的挑战。%Flexible organic non-volatile memory field-effect transistors (ONVMFETs) are promising candidates in the field of flexible organic electronic devices, which can be used in flexible radio frequency tags, memories, integrated circuits and large-area displays, because of their remarkable advantages such as flexibility, lightweight, low cost and large-area organic electronics. On the basis of the introduction of the development of flexible ONVMFETs in terms of substrates, structures and characteristics, the classification of flexible ONVMFETs is summarized. Meanwhile, we discuss the effects of mechanical stress and temperature on the performance of flexible ONVMFET. Finally, some prospects as well as the challenges are pointed out.

  12. Optimization of poly(vinylidene fluoride-trifluoroethylene) films as non-volatile memory for flexible electronics

    KAUST Repository

    Mao, Duo

    2010-05-01

    The impact of thermal treatment and thickness on the polarization and leakage current of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer thin film capacitors has been studied. The evolution of the film morphology, crystallinity and bonding orientation as a function of annealing temperature and thickness were characterized using multiple techniques. Electrical performance of the devices was correlated with the material properties. It was found that annealing at or slightly above the Curie temperature (Tc) is the optimal temperature for high polarization, smooth surface morphology and low leakage current. Higher annealing temperature (but below the melting temperature Tm) favors larger size β crystallites through molecular chain self-organization, resulting in increased film roughness, and the vertical polarization tends to saturate. Metal-Ferroelectric-Metal (MFM) capacitors consistently achieved Ps, Pr and Vc of 8.5 μC/cm2, 7.4 μC/cm2 and 10.2 V, respectively.

  13. Memory device sensitivity trends in aircraft's environment; Evolution de la sensibilite de composants memoires en altitude avion

    Energy Technology Data Exchange (ETDEWEB)

    Bouchet, T.; Fourtine, S. [Aerospatiale-Matra Airbus, 31 - Toulouse (France); Calvet, M.C. [Aerospatiale-Matra Lanceur, 78 - Les Mureaux (France)

    1999-07-01

    The authors present the SEU (single event upset) sensitivity of 31 SRAM (static random access memory) and 8 DRAM (dynamic random access memory) according to their technologies. 2 methods have been used to compute the SEU rate: the NCS (neutron cross section) method and the BGR (burst generation rate) method, the physics data required by both methods have been either found in scientific literature or directly measured. The use of new technologies implies a quicker time response through a dramatic reduction of chip size and of the amount of energy representing 1 bit. The reduction of size makes less particles are likely to interact with the chip but the reduction of the critical charge implies that these interactions are more likely to damage the chip. The SEU sensitivity is then parted between these 2 opposed trends. Results show that for technologies beyond 0,18 {mu}m these 2 trends balance roughly. Nevertheless the feedback experience shows that the number of errors is increasing. This is due to the fact that avionics requires more and more memory to perform numerical functions, the number of bits is increasing so is the risk of errors. As far as SEU is concerned, RAM devices are less and less sensitive comparatively for 1 bit, and DRAM seem to be less sensitive than SRAM. (A.C.)

  14. Development of a thermodynamic control system for the Fontan circulation pulsation device using shape memory alloy fibers.

    Science.gov (United States)

    Yamada, Akihiro; Shiraishi, Yasuyuki; Miura, Hidekazu; Hashem, Hashem Mohamed Omran; Tsuboko, Yusuke; Yamagishi, Masaaki; Yambe, Tomoyuki

    2015-09-01

    The Fontan procedure is one of the common surgical treatments for circulatory reconstruction in pediatric patients with congenital heart disease. In Fontan circulation, low pulsatility may induce localized lung ischemia and may impair the development of pulmonary peripheral endothelial cells. To promote pulmonary circulation in Fontan circulation, we have been developing a pediatric pulmonary circulatory pulsation device using shape memory alloy fibers attached from the outside of total cavopulmonary connection. In this study, we developed a new thermal control system for the device and examined its functions. We mounted on the device 16 fibers connected in parallel around an ePTFE graft circumferentially. To provide optimized contraction, we designed the new thermal control system. The system consisted of a thermistor, a pressure sensor, and a regulator that was controlled by the adaptive thermodynamic transfer functions. We monitored the parameters and calculated heat transfer function as well as pressure distribution on the graft surface. Then we examined and compared the dynamic contractile pressure and changes in surface temperature. As a result, by the application of the control based on the new feedback system analysis, the circumferential contractile pressure increased by 35%. The adaptive thermodynamic regulation was useful for the selection of alternative thresholds of the surface temperature of the graft. The system could achieve effective contraction for the pulsatile flow generation by the device.

  15. Development of a high capacity bubble domain memory element and related epitaxial garnet materials for application in spacecraft data recorders. Item 2: The optimization of material-device parameters for application in bubble domain memory elements for spacecraft data recorders

    Science.gov (United States)

    Besser, P. J.

    1976-01-01

    Bubble domain materials and devices are discussed. One of the materials development goals was a materials system suitable for operation of 16 micrometer period bubble domain devices at 150 kHz over the temperature range -10 C to +60 C. Several material compositions and hard bubble suppression techniques were characterized and the most promising candidates were evaluated in device structures. The technique of pulsed laser stroboscopic microscopy was used to characterize bubble dynamic properties and device performance at 150 kHz. Techniques for large area LPE film growth were developed as a separate task. Device studies included detector optimization, passive replicator design and test and on-chip bridge evaluation. As a technology demonstration an 8 chip memory cell was designed, tested and delivered. The memory elements used in the cell were 10 kilobit serial registers.

  16. Feasibility of Crosslinked Acrylic Shape Memory Polymer for a Thrombectomy Device

    Directory of Open Access Journals (Sweden)

    Andrea D. Muschenborn

    2014-01-01

    Full Text Available Purpose. To evaluate the feasibility of utilizing a system of SMP acrylates for a thrombectomy device by determining an optimal crosslink density that provides both adequate recovery stress for blood clot removal and sufficient strain capacity to enable catheter delivery. Methods. Four thermoset acrylic copolymers containing benzyl methacrylate (BzMA and bisphenol A ethoxylate diacrylate (Mn∼512, BPA were designed with differing thermomechanical properties. Finite element analysis (FEA was performed to ensure that the materials were able to undergo the strains imposed by crimping, and fabricated devices were subjected to force-monitored crimping, constrained recovery, and bench-top thrombectomy. Results. Devices with 25 and 35 mole% BPA exhibited the highest recovery stress and the highest brittle response as they broke upon constrained recovery. On the contrary, the 15 mole% BPA devices endured all testing and their recovery stress (5 kPa enabled successful bench-top thrombectomy in 2/3 times, compared to 0/3 for the devices with the lowest BPA content. Conclusion. While the 15 mole% BPA devices provided the best trade-off between device integrity and performance, other SMP systems that offer recovery stresses above 5 kPa without increasing brittleness to the point of causing device failure would be more suitable for this application.

  17. Controlling methods of a newly developed extra aortic counter-pulsation device using shape memory alloy fibers.

    Science.gov (United States)

    Hashem, Mohamed O; Yamada, A; Tsuboko, Y; Muira, H; Homma, D; Shiraishi, Y; Yambe, T

    2013-01-01

    Diastolic counter-pulsation has been used to provide circulatory augmentation for short term cardiac support. The success of intra-aortic balloon pump (IABP) therapy has generated interest in long term counter-pulsation strategies to treat heart failure patients. The authors have been developing a totally implantable extra aortic pulsation device for the circulatory support of heart failure patients, using 150 µm Ni-Ti anisotropic shape memory alloy (SMA) fibers. These fibers contract by Joule heating with an electric current supply. The special features of our design are as follow: non blood contacting, extra aortic pulsation function synchronizing with the native heart, a wrapping mechanical structure for the aorta in order to achieve its assistance as the aortomyoplsty and the extra aortic balloon pump. The device consisted of rubber silicone wall plates, serially connected for radial contraction. We examined the contractile function of the device, as well as it controlling methods; the phase delay parameter and the pulse width modulation, in a systemic mock circulatory system, with a pneumatically driven silicone left ventricle model, arterial rubber tubing, a peripheral resistance unit, and a venous reservoir. The device was secured around the aortic tubing with a counter-pulsation mode of 1:4 against the heartbeat. Pressure and flow waveforms were measured at the aortic outflow, as well as its driving condition of the contraction phase width and the phase delay. The device achieved its variable phase control for co-pulsation or counter-pulsation modes by changing the phase delay of the SMA fibers. Peak diastolic pressure significantly augmented, mean flow increased (p<0.05) according to the pulse width modulation. Therefore the newly developed extra aortic counter-pulsation device using SMA fibers, through it controlling methods indicated its promising alternative extra aortic approach for non-blood contacting cardiovascular circulatory support.

  18. Non-volatile polymer electrolyte based on poly(propylene carbonate), ionic liquid, and lithium perchlorate for electrochromic devices.

    Science.gov (United States)

    Zhou, Dan; Zhou, Rui; Chen, Chuanxiang; Yee, Wu-Aik; Kong, Junhua; Ding, Guoqiang; Lu, Xuehong

    2013-06-27

    A series of solvent-free ionic liquid (IL)-based polymer electrolytes composed of amorphous and biodegradable poly(propylene carbonate) (PPC) host, LiClO4, and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM(+)BF4(-)) were prepared and characterized for the first time. FTIR studies reveal that the interaction between PPC chains and imidazolium cations weakens the complexation between PPC chains and Li(+) ions. Thermal analysis (DSC and TGA) results show that the incorporation of BMIM(+)BF4(-) into PPC/LiClO4 remarkably decreases the glass transition temperature and improves the thermal stability of the electrolytes. AC impedance results show that the ionic conductivities of the electrolytes are significantly increased with the increase of BMIM(+)BF4(-) amount, the ambient ionic conductivity of the electrolyte at a PPC/LiClO4/BMIM(+)BF4(-) weight ratio of 1/0.2/3 is 1.5 mS/cm, and the ionic transport behavior follows the Arrhenius equation. Both PPC/LiClO4/BMIM(+)BF4(-) and PPC/BMIM(+)BF4(-) electrolytes were applied in electrochromic devices with polyaniline as the electrochromic layer. The PPC/LiClO4/BMIM(+)BF4(-)-based device exhibits much better electrochromic performance in terms of optical contrast and switching time due to the presence of much smaller cations.

  19. Organic ferroelectric/semiconducting nanowire hybrid layer for memory storage

    Science.gov (United States)

    Cai, Ronggang; Kassa, Hailu G.; Haouari, Rachid; Marrani, Alessio; Geerts, Yves H.; Ruzié, Christian; van Breemen, Albert J. J. M.; Gelinck, Gerwin H.; Nysten, Bernard; Hu, Zhijun; Jonas, Alain M.

    2016-03-01

    Ferroelectric materials are important components of sensors, actuators and non-volatile memories. However, possible device configurations are limited due to the need to provide screening charges to ferroelectric interfaces to avoid depolarization. Here we show that, by alternating ferroelectric and semiconducting nanowires over an insulating substrate, the ferroelectric dipole moment can be stabilized by injected free charge carriers accumulating laterally in the neighboring semiconducting nanowires. This lateral electrostatic coupling between ferroelectric and semiconducting nanowires offers new opportunities to design new device architectures. As an example, we demonstrate the fabrication of an elementary non-volatile memory device in a transistor-like configuration, of which the source-drain current exhibits a typical hysteretic behavior with respect to the poling voltage. The potential for size reduction intrinsic to the nanostructured hybrid layer offers opportunities for the development of strongly miniaturized ferroelectric and piezoelectric devices.Ferroelectric materials are important components of sensors, actuators and non-volatile memories. However, possible device configurations are limited due to the need to provide screening charges to ferroelectric interfaces to avoid depolarization. Here we show that, by alternating ferroelectric and semiconducting nanowires over an insulating substrate, the ferroelectric dipole moment can be stabilized by injected free charge carriers accumulating laterally in the neighboring semiconducting nanowires. This lateral electrostatic coupling between ferroelectric and semiconducting nanowires offers new opportunities to design new device architectures. As an example, we demonstrate the fabrication of an elementary non-volatile memory device in a transistor-like configuration, of which the source-drain current exhibits a typical hysteretic behavior with respect to the poling voltage. The potential for size reduction

  20. Reduction of RESET current in phase change memory devices by carbon doping in GeSbTe films

    Science.gov (United States)

    Park, J. H.; Kim, S.-W.; Kim, J. H.; Wu, Z.; Cho, S. L.; Ahn, D.; Ahn, D. H.; Lee, J. M.; Nam, S. U.; Ko, D.-H.

    2015-03-01

    Phase Change Memory (PCM) has been proposed for use as a substitute for flash memory to satisfy the huge demands for high performance and reliability that promise to come in the next generation. In spite of its high scalability, reliability, and simple structure, high writing current, e.g., RESET current, has been a significant obstacle to achieving a high density in storage applications and the low power consumption required for use in mobile applications. We report herein on an attempt to determine the level of carbon incorporated into a GeSbTe (GST) film that is needed to reduce the RESET current of PCM devices. The crystal structure of the film was transformed into an amorphous phase by carbon doping, the stability of which was enhanced with increasing carbon content. This was verified by the small grain size and large band gap that are typically associated with carbon. The increased level of C-Ge covalent bonding is responsible for these enhancements. Thus, the resistance of the carbon doped Ge2Sb2Te5 film was higher than that for an undoped GST film by a factor of 2 orders of magnitude after producing a stable face-centered cubic phase by annealing. As a consequence, the PCM devices showed a significant reduction in RESET current as low as 23% when the carbon content was increased to 11.8 at. %. This can be attributed to the elevated SET resistance, which is proportional to the dynamic resistance of the PCM device, caused by the high resistance due to a carbon doped GST film.

  1. SEMICONDUCTOR DEVICES Effect of trapped charge accumulation on the retention of charge trapping memory

    Science.gov (United States)

    Rui, Jin; Xiaoyan, Liu; Gang, Du; Jinfeng, Kang; Ruqi, Han

    2010-12-01

    The accumulation process of trapped charges in a TANOS cell during P/E cycling is investigated via numerical simulation. The recombination process between trapped charges is an important issue on the retention of charge trapping memory. Our results show that accumulated trapped holes during P/E cycling can have an influence on retention, and the recombination mechanism between trapped charges should be taken into account when evaluating the retention capability of TANOS.

  2. Volatility Discovery

    DEFF Research Database (Denmark)

    Dias, Gustavo Fruet; Scherrer, Cristina; Papailias, Fotis

    The price discovery literature investigates how homogenous securities traded on different markets incorporate information into prices. We take this literature one step further and investigate how these markets contribute to stochastic volatility (volatility discovery). We formally show...... that the realized measures from homogenous securities share a fractional stochastic trend, which is a combination of the price and volatility discovery measures. Furthermore, we show that volatility discovery is associated with the way that market participants process information arrival (market sensitivity...

  3. Characterizations and thermal stability improvement of phase-change memory device containing Ce-doped GeSbTe films

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yu-Jen; Tsai, Min-Chuan; Wang, Chiung-Hsin; Hsieh, Tsung-Eong, E-mail: tehsieh@mail.nctu.edu.tw

    2012-02-29

    Phase-transition temperature of GeSbTe (GST) chalcogenide film was drastically increased from 159 to 236 Degree-Sign C by cerium (Ce) doping (up to 8.6 at.%) without altering the resistivity property of GST. Grain refinement via the solid-solution mechanism and the amplification of p-type semiconducting behavior in Ce-doped GST were observed. They were correlated with the enhancement of thermal stability and data retention property of GST as revealed by exothermal and isothermal analyses. Phase-change memory (PCM) device characterized at various temperatures revealed an effective thermal stability improvement on the threshold voltage of PCM device by Ce doping. - Highlights: Black-Right-Pointing-Pointer Ce doping increased phase-change temperature of GST from 159 to 236 Degree-Sign C. Black-Right-Pointing-Pointer No suppression of resistivity level in amorphous Ce-doped GST. Black-Right-Pointing-Pointer Resistance ratio of amorphous and crystalline Ce-doped GST was preserved at 10{sup 5}. Black-Right-Pointing-Pointer p-type semiconducting behavior of GST was enhanced by Ce-doping. Black-Right-Pointing-Pointer Ce-doping improved the thermal stability of threshold voltage of GST PCM device.

  4. All-polymer bistable resistive memory device based on nanoscale phase-separated PCBM-ferroelectric blends

    KAUST Repository

    Khan, Mohammad A.

    2012-11-21

    All polymer nonvolatile bistable memory devices are fabricated from blends of ferroelectric poly(vinylidenefluoride-trifluoroethylene (P(VDF-TrFE)) and n-type semiconducting [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The nanoscale phase separated films consist of PCBM domains that extend from bottom to top electrode, surrounded by a ferroelectric P(VDF-TrFE) matrix. Highly conducting poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) polymer electrodes are used to engineer band offsets at the interfaces. The devices display resistive switching behavior due to modulation of this injection barrier. With careful optimization of the solvent and processing conditions, it is possible to spin cast very smooth blend films (Rrms ≈ 7.94 nm) and with good reproducibility. The devices exhibit high Ion/I off ratios (≈3 × 103), low read voltages (≈5 V), excellent dielectric response at high frequencies (Ïμr ≈ 8.3 at 1 MHz), and excellent retention characteristics up to 10 000 s. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Volatile Metabolites

    Directory of Open Access Journals (Sweden)

    Daryl D. Rowan

    2011-11-01

    Full Text Available Volatile organic compounds (volatiles comprise a chemically diverse class of low molecular weight organic compounds having an appreciable vapor pressure under ambient conditions. Volatiles produced by plants attract pollinators and seed dispersers, and provide defense against pests and pathogens. For insects, volatiles may act as pheromones directing social behavior or as cues for finding hosts or prey. For humans, volatiles are important as flavorants and as possible disease biomarkers. The marine environment is also a major source of halogenated and sulfur-containing volatiles which participate in the global cycling of these elements. While volatile analysis commonly measures a rather restricted set of analytes, the diverse and extreme physical properties of volatiles provide unique analytical challenges. Volatiles constitute only a small proportion of the total number of metabolites produced by living organisms, however, because of their roles as signaling molecules (semiochemicals both within and between organisms, accurately measuring and determining the roles of these compounds is crucial to an integrated understanding of living systems. This review summarizes recent developments in volatile research from a metabolomics perspective with a focus on the role of recent technical innovation in developing new areas of volatile research and expanding the range of ecological interactions which may be mediated by volatile organic metabolites.

  6. Resistive switching characteristics and conduction mechanisms of nonvolatile memory devices based on Ga and Sn co-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Dohyun; Yun, Dong Yeol; Lee, Nam Hyun; Kim, Tae Whan, E-mail: twk@hanyang.ac.kr

    2015-07-31

    Nonvolatile memory devices were fabricated utilizing Ga and Sn co-doped ZnO (GZTO) films formed by using a solution process method. X-ray diffraction patterns showed that the crystallinity of the annealed GZTO films was an amorphous phase. X-ray photoelectron spectroscopy spectra of the GZTO films depicted Zn−O, Ga−O, and Sn−O bonds. Current–voltage measurements on the Al/GZTO/indium-tin-oxide (ITO) devices at 300 K showed bipolar resistive switching behaviors. The resistances at both the low resistance state (LRS) and high resistance state (HRS) measured at 0.5 V for the devices maintain almost constant without any damage and breakdown above 130 s, indicative of the memory stability of the devices. A difference in the resistance between the HRS and the LRS was more than 1 order of the magnitude. The conduction mechanisms of the HRS in the set process for the Al/GZTO/ITO devices were dominated by a space-charge-limited current model. - Highlights: • Nonvolatile memory devices were fabricated utilizing Ga and Sn co-doped ZnO (GZTO) films. • X-ray diffraction patterns showed that the annealed GZTO films were an amorphous phase. • Current–voltage measurements on the devices showed bipolar resistive switching behaviors. • One order magnitude difference in resistance between low and high resistance states (HRS) • Space charge limited conduction is the dominant conduction mechanisms of the HRS.

  7. Scientific developments of liquid crystal-based optical memory: a review

    Science.gov (United States)

    Prakash, Jai; Chandran, Achu; Biradar, Ashok M.

    2017-01-01

    The memory behavior in liquid crystals (LCs), although rarely observed, has made very significant headway over the past three decades since their discovery in nematic type LCs. It has gone from a mere scientific curiosity to application in variety of commodities. The memory element formed by numerous LCs have been protected by patents, and some commercialized, and used as compensation to non-volatile memory devices, and as memory in personal computers and digital cameras. They also have the low cost, large area, high speed, and high density memory needed for advanced computers and digital electronics. Short and long duration memory behavior for industrial applications have been obtained from several LC materials, and an LC memory with interesting features and applications has been demonstrated using numerous LCs. However, considerable challenges still exist in searching for highly efficient, stable, and long-lifespan materials and methods so that the development of useful memory devices is possible. This review focuses on the scientific and technological approach of fascinating applications of LC-based memory. We address the introduction, development status, novel design and engineering principles, and parameters of LC memory. We also address how the amalgamation of LCs could bring significant change/improvement in memory effects in the emerging field of nanotechnology, and the application of LC memory as the active component for futuristic and interesting memory devices.

  8. Filament theory based WORM memory devices using aluminum/poly(9-vinylcarbazole)/aluminum structures.

    Science.gov (United States)

    Suresh, Aswin; Krishnakumar, Govind; Namboothiry, Manoj A G

    2014-07-14

    Spin coated poly(N-vinylcarbazole) (PVK) sandwiched between thermally evaporated aluminum (Al) electrodes on a glass substrate showed unipolar Write Once Read Many times (WORM) characteristics. The pristine devices were in the low resistance ON state exhibiting ohmic behavior and at a voltage near -2 V, they switched abruptly to the high resistance OFF state showing space charge limited current (SCLC). We suggest that the rupturing of metallic filaments due to Joule heating may explain the effect. The WORM devices exhibited an ON/OFF ratio of 10(8), a retention of 1000 s and an endurance of ∼10(6) cycles in both ON and OFF states.

  9. Investigation on the relationship between CD and CDU in memory devices

    Science.gov (United States)

    Park, Jeongsu; Kim, Daewoo; Kim, Keunjun; Kim, Choidong; Lee, Sungkoo; Kim, Hyeongsoo

    2016-03-01

    As pattern design rule of device shrinks, CD control becomes more critical and important especially for resistance devices. As CD (Critical Dimension) increases, CDU (Critical Dimension Uniformity) becomes worse generally. The question with this relationship is a starting point of our study. Mainly we focused on two points. One is which factor affects CDU. The other is whether CDU degradation with large CD happens at all cases or not. We have analyzed with simulation and experiment results about CDU with splitted mask layout CD under limited conditions such as same equipment, illumination and exposure dose. As a result, we will show the relationship between CD size and CDU.

  10. New internalized distraction device for craniofacial plastic surgery using Ni-free, Ti-based shape memory alloy.

    Science.gov (United States)

    Kanetaka, Hiroyasu; Shimizu, Yoshinaka; Kudo, Tada-aki; Zhang, Ye; Kano, Mitsuhiro; Sano, Yuya; Ichikawa, Hiroyuki; Hosoda, Hideki; Miyazaki, Shuichi

    2010-11-01

    This study was undertaken to examine effects and biocompatibility of a new internalized distraction device made from newly developed Ti-Nb-Al shape memory alloy (SMA). Crania of Wistar rats were expanded using a U-shaped wire of this SMA set on each cranium in an experimental group. At 2 or 4 weeks after operation, the rats were killed; width measurements and three-dimensional observations of crania were conducted using soft x-ray and microfocus x-ray computed tomography photography. After photography, histologic sections were made and stained with hematoxylin and eosin. No pathologic change in the experimental duration was observed macroscopically or histologically. Significantly increased size was found for the rat crania in the experimental group compared with the control group. Results demonstrated the feasibility and biocompatibility of internalized distraction osteogenesis using Ni-free, Ti-based SMA in craniofacial plastic surgery for craniofacial deformities.

  11. Evaluation of the shape memory performances of poly(ε-caprolactone)-based tubular devices for potential biomedical applications

    Science.gov (United States)

    Pandini, Stefano; Borboni, Alberto; Bodini, Ileana; Vetturi, David; Cambiaghi, Danilo; Paderni, Katia; Messori, Massimo; Toselli, Maurizio; Riccò, Theonis

    2014-05-01

    The shape memory behavior of tubular specimens based on crosslinked poly(ɛ-caprolactone) was investigated in order to evaluate their ability i) to restore their shape after being folded in a more compact one, and ii) to exert stress under external confinement (recovery stress). The specimens were prepared following different crosslinking methodologies and with different network densities, in order to tailor the material response in terms of transformation temperatures and recovery stress capabilities. The devices are able to fully recover their shape once heated close to the melting temperature and to exert moderate stresses, that may be controlled through thickness and crosslink density, and whose values were employed to develop a new testing apparatus for the measurement of radial dilation capabilities.

  12. Electromagnetic induction heating of an orthopaedic nickel--titanium shape memory device.

    Science.gov (United States)

    Müller, Christian W; Pfeifer, Ronny; El-Kashef, Tarek; Hurschler, Christof; Herzog, Dirk; Oszwald, Markus; Haasper, Carl; Krettek, Christian; Gösling, Thomas

    2010-12-01

    Shape memory orthopaedic implants made from nickel-titanium (NiTi) might allow the modulation of fracture healing, changing their cross-sectional shape by employing the shape memory effect. We aimed to show the feasibility and safety of contact-free electromagnetic induction heating of NiTi implants in a rat model. A water-cooled generator-oscillator combination was used. Induction characteristics were determined by measuring the temperature increase of a test sample in correlation to generator power and time. In 53 rats, NiTi implants were introduced into the right hind leg. The animals were transferred to the inductor, and the implant was electromagnetically heated to temperatures between 40 and 60°C. Blood samples were drawn before and 4 h after the procedure. IL-1, IL-4, IL-10, TNF-α, and IFN-γ were measured. Animals were euthanized at 3 weeks. Histological specimens from the hind leg and liver were retrieved and examined for inflammatory changes, necrosis, and corrosion pits. Cytokine measurements and histological specimens showed no significant differences among the groups. We concluded that electromagnetic induction heating of orthopedic NiTi implants is feasible and safe in a rat model. This is the first step in the development of new orthopedic implants in which stiffness or rigidity can be modified after implantation to optimize bone-healing.

  13. A Survey of Surface Modification Techniques for Next-Generation Shape Memory Polymer Stent Devices

    Directory of Open Access Journals (Sweden)

    Tina Govindarajan

    2014-08-01

    Full Text Available The search for a single material with ideal surface properties and necessary mechanical properties is on-going, especially with regard to cardiovascular stent materials. Since the majority of stent problems arise from surface issues rather than bulk material deficiencies, surface optimization of a material that already contains the necessary bulk properties is an active area of research. Polymers can be surface-modified using a variety of methods to increase hemocompatibilty by reducing either late-stage restenosis or acute thrombogenicity, or both. These modification methods can be extended to shape memory polymers (SMPs, in an effort to make these materials more surface compatible, based on the application. This review focuses on the role of surface modification of materials, mainly polymers, to improve the hemocompatibility of stent materials; additional discussion of other materials commonly used in stents is also provided. Although shape memory polymers are not yet extensively used for stents, they offer numerous benefits that may make them good candidates for next-generation stents. Surface modification techniques discussed here include roughening, patterning, chemical modification, and surface modification for biomolecule and drug delivery.

  14. Silicon nanowire charge-trap memory incorporating self-assembled iron oxide quantum dots.

    Science.gov (United States)

    Huang, Ruo-Gu; Heath, James R

    2012-11-19

    Charge-trap non-volatile memory devices based upon the precise integration of quantum dot storage elements with silicon nanowire field-effect transistors are described. Template-assisted assembly yields an ordered array of FeO QDs within the trenches that separate highly aligned SiNWs, and injected charges are reversibly stored via Fowler-Nordheim tunneling into the QDs. Stored charges shift the transistor threshold voltages, providing the basis for a memory device. Quantum dot size is found to strongly influence memory performance metrics.

  15. Ultra-Low Power Memory Design in Scaled Technology Nodes

    DEFF Research Database (Denmark)

    Zeinali, Behzad

    2017-01-01

    technology nodes, this thesis also investigates emerging non-volatile spintronics memories. In this respect, STT-MRAMs and SOT-MRAMs are studied and their design challenges are explored. To improve the read performance of STT-MRAMs, a novel non-destructive self-reference sensing scheme is proposed enabling......In today’s chip design, robust memory design is one of the key challenges of process technology scaling. The steady pace of process technology scaling allows doubling memory array sizes approximately every 2 years. However, further scaling emerges undesirable effects which threaten the power......-efficiency, robust performance and high-density of memories. This thesis addresses these challenges and propose different solutions at the device, circuit and architecture levels in traditional SRAMs and emerging spintronics memories. Based on the fact that SRAMs are the dominant structure in cache memories, which...

  16. Reactive Ion Etching as Cleaning Method Post Chemical Mechanical Polishing for Phase Change Memory Device

    Institute of Scientific and Technical Information of China (English)

    ZHONG Min; SONG Zhi-Tang; LIU Bo; FENG Song-Lin; CHEN Bomy

    2008-01-01

    In order to improve nano-scale phase change memory performance,a super-clean interface should be obtained after chemical mechanical polishing (CMP) of Ge2Sb2Te5 phase change films.We use reactive ion etching (RIE) as the cleaning method.The cleaning effect is analysed by scanning electron microscopy and an energy dispersive spectrometer.The results show that particle residue on the surface has been removed.Meanwhile,Ge2 Sb2 Te5 material stoichiometric content ratios are unchanged.After the top electrode is deposited,currentvoltage characteristics test demonstrates that the set threshold voltage is reduced from 13 V to 2.7V and the threshold current from 0.1 mA to 0.025 mA.Furthermore,we analyse the RIE cleaning principle and compare it with the ultrasonic method.

  17. Rare-Earth Ions in Niobium-Based Devices as a Quantum Memory: Magneto-Optical Effects on Room Temperature Electrical Transport

    Science.gov (United States)

    2016-09-01

    University of Delaware , Newark, DE. 5f. WORK UNIT NUMBER REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-01-0188 The public reporting burden for...ANSI Std . Z39.18 September 2016 Final Rare-Earth Ions in Niobium-based Devices as a Quantum Memory Magneto-Optical Effects on Room Temperature

  18. A memory efficient implementation scheme of Gauss error function in a Laguerre-Volterra network for neuroprosthetic devices.

    Science.gov (United States)

    Li, Will X Y; Cui, Ke; Zhang, Wei

    2017-04-01

    Cognitive neural prosthesis is a manmade device which can be used to restore or compensate for lost human cognitive modalities. The generalized Laguerre-Volterra (GLV) network serves as a robust mathematical underpinning for the development of such prosthetic instrument. In this paper, a hardware implementation scheme of Gauss error function for the GLV network targeting reconfigurable platforms is reported. Numerical approximations are formulated which transform the computation of nonelementary function into combinational operations of elementary functions, and memory-intensive look-up table (LUT) based approaches can therefore be circumvented. The computational precision can be made adjustable with the utilization of an error compensation scheme, which is proposed based on the experimental observation of the mathematical characteristics of the error trajectory. The precision can be further customizable by exploiting the run-time characteristics of the reconfigurable system. Compared to the polynomial expansion based implementation scheme, the utilization of slice LUTs, occupied slices, and DSP48E1s on a Xilinx XC6VLX240T field-programmable gate array has decreased by 94.2%, 94.1%, and 90.0%, respectively. While compared to the look-up table based scheme, 1.0×10(17) bits of storage can be spared under the maximum allowable error of 1.0×10(-3). The proposed implementation scheme can be employed in the study of large-scale neural ensemble activity and in the design and development of neural prosthetic device.

  19. System of extraction of volatiles from soil using microwave processes

    Science.gov (United States)

    Ethridge, Edwin C. (Inventor); Kaukler, William F. (Inventor)

    2013-01-01

    A device for the extraction and collection of volatiles from soil or planetary regolith. The device utilizes core drilled holes to gain access to underlying volatiles below the surface. Microwave energy beamed into the holes penetrates through the soil or regolith to heat it, and thereby produces vapor by sublimation. The device confines and transports volatiles to a cold trap for collection.

  20. Spin-transfer torque magnetoresistive random-access memory technologies for normally off computing (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Ando, K., E-mail: ando-koji@aist.go.jp; Yuasa, S. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568 (Japan); Fujita, S.; Ito, J.; Yoda, H. [Toshiba Corporation, Kawasaki 212-8582 (Japan); Suzuki, Y. [Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan); Nakatani, Y. [Department of Communication Engineering and Informatics, University of Electro-Communication, Chofu 182-8585 (Japan); Miyazaki, T. [WPI-AIMR, Tohoku University, Sendai 980-8577 (Japan)

    2014-05-07

    Most parts of present computer systems are made of volatile devices, and the power to supply them to avoid information loss causes huge energy losses. We can eliminate this meaningless energy loss by utilizing the non-volatile function of advanced spin-transfer torque magnetoresistive random-access memory (STT-MRAM) technology and create a new type of computer, i.e., normally off computers. Critical tasks to achieve normally off computers are implementations of STT-MRAM technologies in the main memory and low-level cache memories. STT-MRAM technology for applications to the main memory has been successfully developed by using perpendicular STT-MRAMs, and faster STT-MRAM technologies for applications to the cache memory are now being developed. The present status of STT-MRAMs and challenges that remain for normally off computers are discussed.

  1. Virtual volatility

    Science.gov (United States)

    Silva, A. Christian; Prange, Richard E.

    2007-03-01

    We introduce the concept of virtual volatility. This simple but new measure shows how to quantify the uncertainty in the forecast of the drift component of a random walk. The virtual volatility also is a useful tool in understanding the stochastic process for a given portfolio. In particular, and as an example, we were able to identify mean reversion effect in our portfolio. Finally, we briefly discuss the potential practical effect of the virtual volatility on an investor asset allocation strategy.

  2. Virtual volatility

    OpenAIRE

    A. Christian Silva; Prange, Richard E.

    2006-01-01

    We introduce the concept of virtual volatility. This simple but new measure shows how to quantify the uncertainty in the forecast of the drift component of a random walk. The virtual volatility also is a useful tool in understanding the stochastic process for a given portfolio. In particular, and as an example, we were able to identify mean reversion effect in our portfolio. Finally, we briefly discuss the potential practical effect of the virtual volatility on an investor asset allocation st...

  3. Plant volatiles.

    Science.gov (United States)

    Baldwin, Ian T

    2010-05-11

    Plant volatiles are the metabolites that plants release into the air. The quantities released are not trivial. Almost one-fifth of the atmospheric CO2 fixed by land plants is released back into the air each day as volatiles. Plants are champion synthetic chemists; they take advantage of their anabolic prowess to produce volatiles, which they use to protect themselves against biotic and abiotic stresses and to provide information - and potentially disinformation - to mutualists and competitors alike. As transferors of information, volatiles have provided plants with solutions to the challenges associated with being rooted in the ground and immobile.

  4. Preserving color fidelity for display devices using scalable memory compression architecture for text, graphics, and video

    Science.gov (United States)

    Lebowsky, Fritz; Nicolas, Marina

    2014-01-01

    High-end monitors and TVs based on LCD technology continue to increase their native display resolution to 4k by 2k and beyond. Subsequently, uncompressed pixel amplitude processing becomes costly not only when transmitting over cable or wireless communication channels, but also when processing with array processor architectures. For motion video content, spatial preprocessing from YCbCr 444 to YCbCr 420 is widely accepted. However, due to spatial low pass filtering in horizontal and vertical direction, quality and readability of small text and graphics content is heavily compromised when color contrast is high in chrominance channels. On the other hand, straight forward YCbCr 444 compression based on mathematical error coding schemes quite often lacks optimal adaptation to visually significant image content. We present a block-based memory compression architecture for text, graphics, and video enabling multidimensional error minimization with context sensitive control of visually noticeable artifacts. As a result of analyzing image context locally, the number of operations per pixel can be significantly reduced, especially when implemented on array processor architectures. A comparative analysis based on some competitive solutions highlights the effectiveness of our approach, identifies its current limitations with regard to high quality color rendering, and illustrates remaining visual artifacts.

  5. Dielectric elastomer memory

    Science.gov (United States)

    O'Brien, Benjamin M.; McKay, Thomas G.; Xie, Sheng Q.; Calius, Emilio P.; Anderson, Iain A.

    2011-04-01

    Life shows us that the distribution of intelligence throughout flexible muscular networks is a highly successful solution to a wide range of challenges, for example: human hearts, octopi, or even starfish. Recreating this success in engineered systems requires soft actuator technologies with embedded sensing and intelligence. Dielectric Elastomer Actuator(s) (DEA) are promising due to their large stresses and strains, as well as quiet flexible multimodal operation. Recently dielectric elastomer devices were presented with built in sensor, driver, and logic capability enabled by a new concept called the Dielectric Elastomer Switch(es) (DES). DES use electrode piezoresistivity to control the charge on DEA and enable the distribution of intelligence throughout a DEA device. In this paper we advance the capabilities of DES further to form volatile memory elements. A set reset flip-flop with inverted reset line was developed based on DES and DEA. With a 3200V supply the flip-flop behaved appropriately and demonstrated the creation of dielectric elastomer memory capable of changing state in response to 1 second long set and reset pulses. This memory opens up applications such as oscillator, de-bounce, timing, and sequential logic circuits; all of which could be distributed throughout biomimetic actuator arrays. Future work will include miniaturisation to improve response speed, implementation into more complex circuits, and investigation of longer lasting and more sensitive switching materials.

  6. Fluctuation behaviors of financial return volatility duration

    Science.gov (United States)

    Niu, Hongli; Wang, Jun; Lu, Yunfan

    2016-04-01

    It is of significantly crucial to understand the return volatility of financial markets because it helps to quantify the investment risk, optimize the portfolio, and provide a key input of option pricing models. The characteristics of isolated high volatility events above certain threshold in price fluctuations and the distributions of return intervals between these events arouse great interest in financial research. In the present work, we introduce a new concept of daily return volatility duration, which is defined as the shortest passage time when the future volatility intensity is above or below the current volatility intensity (without predefining a threshold). The statistical properties of the daily return volatility durations for seven representative stock indices from the world financial markets are investigated. Some useful and interesting empirical results of these volatility duration series about the probability distributions, memory effects and multifractal properties are obtained. These results also show that the proposed stock volatility series analysis is a meaningful and beneficial trial.

  7. Multiferroic domain boundaries as active memory devices: trajectories towards domain boundary engineering.

    Science.gov (United States)

    Salje, Ekhard K H

    2010-04-06

    Twin boundaries in ferroelastics and curved interfaces between crystalline and amorphous zircon can, in principle, act as multiferroic structural elements and lead the way to the discovery of novel multiferroic devices which are based on structurally heterogeneous materials. While this paradigm has not yet been explored in full, this review shows that physical and chemical properties can vary dramatically inside twin boundaries and interfaces. Properties that have been already been explored include electric dipoles in a non-polar matrix, the appearance of superconductivity in twin boundaries and the catalytic reaction of hydrous species in interfaces of radiation damaged material. Some of the fundamental physical and chemical properties of twin boundaries and related interfaces are described and possible applications are outlined.

  8. 基于MCMC的贝叶斯长记忆随机波动模型研究%Markov Chain Monte Carlo Methods for Bayesian Long Memory Stochastic Volatility Models

    Institute of Scientific and Technical Information of China (English)

    郝立亚; 朱慧明; 李素芳; 曾惠芳

    2011-01-01

    针对贝叶斯长记忆随机波动模型的单步Gibbs抽样算法效率低下的问题,通过对模型在状态空间框架下的近似表示,将向前滤波向后抽样算法引入对波动变量的估计过程中,同时在贝叶斯框架下分析了模型参数的满条件后验分布,设计出Gibbs联合抽样算法.更进一步,在对模型进行参数估计的基础上,提出波动变量的向前多步预报分布的估计方法.模拟实验结果表明:联合Gibbs抽样算法能够在保证估计精度的基础上得到优于单步Gibbs抽样方法的抽样效率,对预报分布的特征分析可用于对金融时间序列的风险控制.%This paper was concerned with simulation-based inference in generalized models of stochastic volatility with long memory. A more efficient Markov Chain Monte Carlo sampling method was exploited to the analysis of the model, compared with the single step Gibbs sampling method. Based on the truncated likelihood method, in which the long memory stochastic volatility model was expressed as a linear state space model, we utilized the forward filtering backward sampling method to sample all the unobserved volatilities simultaneously. A simulation method for Bayesian prediction analysis of the volatilities was also developed. The simulation study has given the results of estimated pa-rameters and evaluated the performance of our method. Moreover, the prediction analysis of the volatility can be used to control the risk of financial series.

  9. Modeling and Forecasting the Volatility of Eastern European Emerging Markets

    Directory of Open Access Journals (Sweden)

    Sang Hoon Kang

    2009-06-01

    Full Text Available This study has attempted to seek a volatility forecasting model that can reflect sufficiently the long memory characteristic in the volatility of four Eastern European emerging stock markets, naThis study has attempted to seek a volatility forecasting model that can reflect sufficiently the long memory characteristic in the volatility of four Eastern European emerging stock markets, namely, Hungary, Poland, Russia, and Slovakia. From the results of our empirical analysis, we found that the FIGARCH model is better equipped to capture the long memory property in the volatility of these markets than the GARCH and IGARCH models. More importantly, the FIGARCH model is found to provide superior performance in one-day-ahead volatility forecasts. Thus, this study recommends researchers, portfolio managers, and traders to use the long memory FIGARCH model in analyzing and forecasting the volatility dynamics of Eastern European emerging markets.

  10. Unstable volatility

    DEFF Research Database (Denmark)

    Casas, Isabel; Gijbels, Irène

    2012-01-01

    The objective of this paper is to introduce the break-preserving local linear (BPLL) estimator for the estimation of unstable volatility functions for independent and asymptotically independent processes. Breaks in the structure of the conditional mean and/or the volatility functions are common i...

  11. Unstable volatility

    DEFF Research Database (Denmark)

    Casas, Isabel; Gijbels, Irène

    2012-01-01

    The objective of this paper is to introduce the break-preserving local linear (BPLL) estimator for the estimation of unstable volatility functions for independent and asymptotically independent processes. Breaks in the structure of the conditional mean and/or the volatility functions are common i...

  12. Charge storage properties of InP quantum dots in GaAs metal-oxide-semiconductor based nonvolatile flash memory devices

    Science.gov (United States)

    Kundu, Souvik; Halder, Nripendra N.; Biswas, Pranab; Biswas, D.; Banerji, P.; Mukherjee, Rabibrata; Chakraborty, S.

    2012-11-01

    Metal organic vapor phase epitaxially grown 5 nm InP quantum dots (QDs) were embedded as charge storage elements between high-k control and tunneling dielectric layers in GaAs metal-oxide-semiconductor based nonvolatile memory devices. The QDs trap more electrons resulting in a large memory window (6.3 V) along with low leakage due to Coulomb blockade effect. 16.5% charge loss was found even after 105 s indicating its good charge storing potential. The programming and erasing operations were discussed with proposed band diagram.

  13. Adaptive microwave impedance memory effect in a ferromagnetic insulator

    Science.gov (United States)

    Lee, Hanju; Friedman, Barry; Lee, Kiejin

    2016-12-01

    Adaptive electronics, which are often referred to as memristive systems as they often rely on a memristor (memory resistor), are an emerging technology inspired by adaptive biological systems. Dissipative systems may provide a proper platform to implement an adaptive system due to its inherent adaptive property that parameters describing the system are optimized to maximize the entropy production for a given environment. Here, we report that a non-volatile and reversible adaptive microwave impedance memory device can be realized through the adaptive property of the dissipative structure of the driven ferromagnetic system. Like the memristive device, the microwave impedance of the device is modulated as a function of excitation microwave passing through the device. This kind of new device may not only helpful to implement adaptive information processing technologies, but also may be useful to investigate and understand the underlying mechanism of spontaneous formation of complex and ordered structures.

  14. Effect of annealing treatment on the electrical characteristics of Pt/Cr-embedded ZnO/Pt resistance random access memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Li-Chun, E-mail: lcchang@mail.mcut.edu.tw [Department of Materials Engineering, Ming Chi University of Technology, No. 84, Gongzhuan Rd., Taishan Dist., New Taipei City 24301, Taiwan and Center for Thin Film Technologies and Applications, Ming Chi University of Technology, No. 84, Gongzhuan Rd., Taishan Dist., New Taipei City 24301, Taiwan (China); Kao, Hsuan-Ling [Department of Electronic Engineering, Chang Gung University, No. 259, Wen-Hwa 1st Rd., Kwei-Shan Tao-Yuan 33302, Taiwan (China); Liu, Keng-Hao [Department of Electronic Engineering, Chang Gung University, Tao-Yuan, Taiwan (China)

    2014-03-15

    ZnO/Cr/ZnO trilayer films sandwiched with Pt electrodes were prepared for nonvolatile resistive memory applications. The threshold voltage of a ZnO device embedded with a 3-nm Cr interlayer was approximately 50% lower than that of a ZnO monolayer device. This study investigated threshold voltage as a function of Cr thickness. Both the ZnO monolayer device and the Cr-embedded ZnO device structures exhibited resistance switching under electrical bias both before and after rapid thermal annealing (RTA) treatment, but resistive switching effects in the two cases exhibited distinct characteristics. Compared with the as-fabricated device, the memory cell after RTA demonstrated remarkable device parameter improvements, including a lower threshold voltage, a lower write current, and a higher R{sub off}/R{sub on} ratio. Both transmission electron microscope observations and Auger electron spectroscopy revealed that the Cr charge trapping layer in Cr-embedded ZnO dispersed uniformly into the storage medium after RTA, and x-ray diffraction and x-ray photoelectron spectroscopy analyses demonstrated that the Cr atoms lost electrons to become Cr{sup 3+} ions after dispersion. These results indicated that the altered status of Cr in ZnO/Cr/ZnO trilayer films during RTA treatment was responsible for the switching mechanism transition.

  15. Demo-application of shape memory alloy devices: the rehabilitation of the S. Giorgio Church bell tower

    Science.gov (United States)

    Indirli, Maurizio; Castellano, Maria G.; Clemente, Paolo; Martelli, Alessandro

    2001-07-01

    This paper describes the rehabilitation of the S. Giorgio Church Bell-Tower (Trignano, Municipality of S. Martino in Rio, Reggio Emilia, Italy), completed in September 1999. This masonry building, seriously damaged by the earthquake of October 15th 1996 which struck the Reggio Emilia and Modena Districts, Italy), was investigated by the authors immediately after the seismic event, as other ancient Cultural Heritage Structures (CUHESs) in the same area. In the past, seismic events have visited substantial destruction that translates into a significant loss of architectural heritage. The most common solution traditionally used to enhance the CUHESs seismic behaviour is the introduction of localized reinforcements, usually Traditional Steel Ties (TSTs), increasing stability and ductility. Anyway, in many cases said reinforcement techniques, often too invasive, proved to be inadequate to prevent collapse. For these reasons, the Bell-Tower intervention applies Innovative Antiseismic Techniques (IATs) by the use of superelastic Shape Memory Alloy (SMA) Devices (SMADs), a technology developed after a large amount of theoretical studies, numerical analyses and test campaigns. The SMADs, which can be considered a powerful tool with respect to the traditional methods, provide acceleration reduction, force limitation and energy dissipation. Furthermore, they are characterized by low invasivity and complete reversibility. When another earthquake occurred on June 18th 2000, with the same epicenter and a comparable Richter Magnitudo, the Bell-Tower, subjected to a new investigation, showed no damage of any type. Thus, the new seismic event has been the best verification of the retrofit intervention.

  16. Use of the asymmetric planar hall resistance of an Fe film for possible multi-value memory device applications.

    Science.gov (United States)

    Yoo, Taehee; Khym, S; Lee, Hakjoon; Lee, Sangyeop; Kim, Shinhee; Shin, Jinsik; Lee, Sanghoon; Liu, X; Furdyna, J K

    2011-07-01

    Systematic planar Hall measurements have been performed on a ferromagnetic Fe film grown on a standard (001) GaAs substrate at room temperature. The angular dependence of the planar Hall effect revealed the presence of both four-fold (cubic) and two-fold (uniaxial) anisotropies in the 7 nm thick Fe film. The dominance of the four-fold symmetric anisotropy, however, provided four magnetic easy axes near the (100) direction, which results in a two step switching phenomenon in the magnetization reversal process. An interesting asymmetric hysteresis loop was observed in the planar Hall resistance (PHR) when the turning point of the field scan is set at the value in the region of the second transition. The intermediate resistance states appearing in the asymmetric PHR loop were understood in terms of mutli-domain structures formed during the second switching of magnetization. Such multi-domain structure of the Fe film showing robust time stability provided additional Hall resistance states, which can be used for multi-valued memory device applications.

  17. Review of radiation effects on ReRAM devices and technology

    Science.gov (United States)

    Gonzalez-Velo, Yago; Barnaby, Hugh J.; Kozicki, Michael N.

    2017-08-01

    A review of the ionizing radiation effects on resistive random access memory (ReRAM) technology and devices is presented in this article. The review focuses on vertical devices exhibiting bipolar resistance switching, devices that have already exhibited interesting properties and characteristics for memory applications and, in particular, for non-volatile memory applications. Non-volatile memories are important devices for any type of electronic and embedded system, as they are for space applications. In such applications, specific environmental issues related to the existence of cosmic rays and Van Allen radiation belts around the Earth contribute to specific failure mechanisms related to the energy deposition induced by such ionizing radiation. Such effects are important in non-volatile memory as the current leading technology, i.e. flash-based technology, is sensitive to the total ionizing dose (TID) and single-event effects. New technologies such as ReRAM, if competing with or complementing the existing non-volatile area of memories from the point of view of performance, also have to exhibit great reliability for use in radiation environments such as space. This has driven research on the radiation effects of such ReRAM technology, on both the conductive-bridge RAM as well as the valence-change memories, or OxRAM variants of the technology. Initial characterizations of ReRAM technology showed a high degree of resilience to TID, developing researchers’ interest in characterizing such resilience as well as investigating the cause of such behavior. The state of the art of such research is reviewed in this article.

  18. In vitro and in vivo evaluation of a shape memory polymer foam-over-wire embolization device delivered in saccular aneurysm models.

    Science.gov (United States)

    Boyle, Anthony J; Landsman, Todd L; Wierzbicki, Mark A; Nash, Landon D; Hwang, Wonjun; Miller, Matthew W; Tuzun, Egemen; Hasan, Sayyeda M; Maitland, Duncan J

    2016-10-01

    Current endovascular therapies for intracranial saccular aneurysms result in high recurrence rates due to poor tissue healing, coil compaction, and aneurysm growth. We propose treatment of saccular aneurysms using shape memory polymer (SMP) foam to improve clinical outcomes. SMP foam-over-wire (FOW) embolization devices were delivered to in vitro and in vivo porcine saccular aneurysm models to evaluate device efficacy, aneurysm occlusion, and acute clotting. FOW devices demonstrated effective delivery and stable implantation in vitro. In vivo porcine aneurysms were successfully occluded using FOW devices with theoretical volume occlusion values greater than 72% and rapid, stable thrombus formation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1407-1415, 2016.

  19. Multilevel charging and discharging mechanisms of nonvolatile memory devices based on nanocomposites consisting of monolayered Au nanoparticles embedded in a polystyrene layer

    Science.gov (United States)

    Yeol Yun, Dong; Hyun Lee, Nam; Seong Kim, Hak; Wook Lee, Sang; Whan Kim, Tae

    2014-01-01

    Capacitance-voltage (C-V) curves for Al/Au nanoparticles embedded in a polystyrene (PS) layer/p-Si devices at 300 K showed a metal-insulator-semiconductor behavior with flat-band voltage shifts of the C-V curves due to the existence of charge trapping. Memory windows between 2.6 and 9.9 V were observed at different sweep voltages, indicative of multilevel behavior. Capacitance-time measurements demonstrated that the charge-trapping capability of Au nanoparticles embedded in a PS layer was maintained for retention times larger than 1 × 104 s without significant degradation. The multilevel charging and discharging mechanisms of the memory devices are described on the basis of the experimental results.

  20. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition

    Science.gov (United States)

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-06-01

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption.

  1. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition.

    Science.gov (United States)

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-06-17

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption.

  2. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition

    Science.gov (United States)

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-01-01

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption. PMID:27312225

  3. Influence of Thermal Annealing Treatment on Bipolar Switching Properties of Vanadium Oxide Thin-Film Resistance Random-Access Memory Devices

    Science.gov (United States)

    Chen, Kai-Huang; Cheng, Chien-Min; Kao, Ming-Cheng; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Wu, Sean; Su, Feng-Yi

    2016-12-01

    The bipolar switching properties and electrical conduction mechanism of vanadium oxide thin-film resistive random-access memory (RRAM) devices obtained using a rapid thermal annealing (RTA) process have been investigated in high-resistive status/low-resistive status (HRS/LRS) and are discussed herein. In addition, the resistance switching properties and quality improvement of the vanadium oxide thin-film RRAM devices were measured by x-ray diffraction (XRD) analysis, x-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and current-voltage (I-V) measurements. The activation energy of the hopping conduction mechanism in the devices was investigated based on Arrhenius plots in HRS and LRS. The hopping conduction distance and activation energy barrier were obtained as 12 nm and 45 meV, respectively. The thermal annealing process is recognized as a candidate method for fabrication of thin-film RRAM devices, being compatible with integrated circuit technology for nonvolatile memory devices.

  4. Influence of Thermal Annealing Treatment on Bipolar Switching Properties of Vanadium Oxide Thin-Film Resistance Random-Access Memory Devices

    Science.gov (United States)

    Chen, Kai-Huang; Cheng, Chien-Min; Kao, Ming-Cheng; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Wu, Sean; Su, Feng-Yi

    2017-04-01

    The bipolar switching properties and electrical conduction mechanism of vanadium oxide thin-film resistive random-access memory (RRAM) devices obtained using a rapid thermal annealing (RTA) process have been investigated in high-resistive status/low-resistive status (HRS/LRS) and are discussed herein. In addition, the resistance switching properties and quality improvement of the vanadium oxide thin-film RRAM devices were measured by x-ray diffraction (XRD) analysis, x-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and current-voltage ( I- V) measurements. The activation energy of the hopping conduction mechanism in the devices was investigated based on Arrhenius plots in HRS and LRS. The hopping conduction distance and activation energy barrier were obtained as 12 nm and 45 meV, respectively. The thermal annealing process is recognized as a candidate method for fabrication of thin-film RRAM devices, being compatible with integrated circuit technology for nonvolatile memory devices.

  5. A simple device unit consisting of all NiO storage and switch elements for multilevel terabit nonvolatile random access memory.

    Science.gov (United States)

    Lee, Myoung-Jae; Ahn, Seung-Eon; Lee, Chang Bum; Kim, Chang-Jung; Jeon, Sanghun; Chung, U-In; Yoo, In-Kyeong; Park, Gyeong-Su; Han, Seungwu; Hwang, In Rok; Park, Bae-Ho

    2011-11-01

    Present charge-based silicon memories are unlikely to reach terabit densities because of scaling limits. As the feature size of memory shrinks to just tens of nanometers, there is insufficient volume available to store charge. Also, process temperatures higher than 800 °C make silicon incompatible with three-dimensional (3D) stacking structures. Here we present a device unit consisting of all NiO storage and switch elements for multilevel terabit nonvolatile random access memory using resistance switching. It is demonstrated that NiO films are scalable to around 30 nm and compatible with multilevel cell technology. The device unit can be a building block for 3D stacking structure because of its simple structure and constituent, high performance, and process temperature lower than 300 °C. Memory resistance switching of NiO storage element is accompanied by an increase in density of grain boundary while threshold resistance switching of NiO switch element is controlled by current flowing through NiO film.

  6. Resistive switching effect of Ag/MoS2/FTO device

    Science.gov (United States)

    Sun, Bai; Zhao, Wenxi; Liu, Yonghong; Chen, Peng

    2015-09-01

    The electric-pulse-driven resistance change of metal/oxides/metal structure, which is called resistive switching effect, is a fascinating phenomenon for the development of next generation non-volatile memory. In this work, an outstanding bipolar resistive switching behavior of Ag/MoS2/fluorine-doped tin oxide (FTO) device is demonstrated. The device can maintain superior reversible stability over 100 cycles with an OFF/ON-state resistance ratio of about 103 at room temperature.

  7. Chasing volatility

    DEFF Research Database (Denmark)

    Caporin, Massimiliano; Rossi, Eduardo; Santucci de Magistris, Paolo

    The realized volatility of financial returns is characterized by persistence and occurrence of unpreditable large increments. To capture those features, we introduce the Multiplicative Error Model with jumps (MEM-J). When a jump component is included in the multiplicative specification, the condi...... models, the introduction of the jump component provides a sensible improvement in the fit, as well as for in-sample and out-of-sample volatility tail forecasts....

  8. Volatility Risk

    OpenAIRE

    Zhiguang Wang

    2009-01-01

    Classical capital asset pricing theory tells us that riskaverse investors would require higher returns to compensate for higher risk on an investment. One type of risk is price (return) risk, which reflects uncertainty in the price level and is measured by the volatility (standard deviation) of asset returns. Volatility itself is also known to be random and hence is perceived as another type of risk. Investors can bear price risk in exchange for a higher return. But are investors willing to p...

  9. Modeling and simulation of low power ferroelectric non-volatile memory tunnel field effect transistors using silicon-doped hafnium oxide as gate dielectric

    OpenAIRE

    Saeidi, A.; Biswas, A.; Ionescu, Adrian M.

    2016-01-01

    The implementation and operation of the nonvolatile ferroelectric memory (NVM) tunnel field effect transistors with silicon-doped HfO2 is proposed and theoretically examined for the first time, showing that ferroelectric nonvolatile tunnel field effect transistor (Fe-TFET) can operate as ultra-low power nonvolatile memory even in aggressively scaled dimensions. A Fe-TFET analytical model is derived by combining the pseudo 2-D Poisson equation and Maxwell’s equation. The model describes the Fe...

  10. Forecasting volatility of crude oil markets

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sang Hoon [Department of Business Administration, Gyeongsang National University, Jinju, 660-701 (Korea); Kang, Sang-Mok; Yoon, Seong-Min [Department of Economics, Pusan National University, Busan, 609-735 (Korea)

    2009-01-15

    This article investigates the efficacy of a volatility model for three crude oil markets - Brent, Dubai, and West Texas Intermediate (WTI) - with regard to its ability to forecast and identify volatility stylized facts, in particular volatility persistence or long memory. In this context, we assess persistence in the volatility of the three crude oil prices using conditional volatility models. The CGARCH and FIGARCH models are better equipped to capture persistence than are the GARCH and IGARCH models. The CGARCH and FIGARCH models also provide superior performance in out-of-sample volatility forecasts. We conclude that the CGARCH and FIGARCH models are useful for modeling and forecasting persistence in the volatility of crude oil prices. (author)

  11. MBE-grown Si and Si(1-x)Ge(x) quantum dots embedded within epitaxial Gd2O3 on Si(111) substrate for floating gate memory device.

    Science.gov (United States)

    Manna, S; Aluguri, R; Katiyar, A; Das, S; Laha, A; Osten, H J; Ray, S K

    2013-12-20

    Si and Si(1-x)Ge(x) quantum dots embedded within epitaxial Gd2O3 grown by molecular beam epitaxy have been studied for application in floating gate memory devices. The effect of interface traps and the role of quantum dots on the memory properties have been studied using frequency-dependent capacitance-voltage and conductance-voltage measurements. Multilayer quantum dot memory comprising four and five layers of Si quantum dots exhibits a superior memory window to that of single-layer quantum dot memory devices. It has also been observed that single-layer Si(1-x)Ge(x) quantum dots show better memory characteristics than single-layer Si quantum dots.

  12. High-Performance, Reliable Object-Based NVRAM Devices

    OpenAIRE

    Kang, Yangwook

    2014-01-01

    Non-volatile memory (NVRAM) storage devices are increasingly used in both consumer and enterprise systems, providing high performance and low energy consumption compared to hard drives. Unfortunately, an inflexible block interface and multiple I/O subsystems designed for slow hard drives make it difficult to utilize NVRAMs in a portable and efficient manner. For example, in the OS storage stack, I/O workloads are reshaped and throttled to generate a small number of concurrent I/O requests, th...

  13. 1D versus 3D quantum confinement in 1-5 nm ZnO nanoparticle agglomerations for application in charge-trapping memory devices

    Science.gov (United States)

    El-Atab, Nazek; Nayfeh, Ammar

    2016-07-01

    ZnO nanoparticles (NPs) have attracted considerable interest from industry and researchers due to their excellent properties with applications in optoelectronic devices, sunscreens, photocatalysts, sensors, biomedical sciences, etc. However, the agglomeration of NPs is considered to be a limiting factor since it can affect the desirable physical and electronic properties of the NPs. In this work, 1-5 nm ZnO NPs deposited by spin- and dip-coating techniques are studied. The electronic and physical properties of the resulting agglomerations of NPs are studied using UV-vis-NIR spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy (TEM), and their application in metal-oxide-semiconductor (MOS) memory devices is analyzed. The results show that both dip- and spin-coating techniques lead to agglomerations of the NPs mostly in the horizontal direction. However, the width of the ZnO clusters is larger with dip-coating which leads to 1D quantum confinement, while the smaller ZnO clusters obtained by spin-coating enable 3D quantum confinement in ZnO. The ZnO NPs are used as the charge-trapping layer of a MOS-memory structure and the analysis of the high-frequency C-V measurements allow further understanding of the electronic properties of the ZnO agglomerations. A large memory window is achieved in both devices which confirms that ZnO NPs provide large charge-trapping density. In addition, ZnO confined in 3D allows for a larger memory window at lower operating voltages due to the Poole-Frenkel charge-emission mechanism.

  14. DESTINY: A Comprehensive Tool with 3D and Multi-Level Cell Memory Modeling Capability

    Directory of Open Access Journals (Sweden)

    Sparsh Mittal

    2017-09-01

    Full Text Available To enable the design of large capacity memory structures, novel memory technologies such as non-volatile memory (NVM and novel fabrication approaches, e.g., 3D stacking and multi-level cell (MLC design have been explored. The existing modeling tools, however, cover only a few memory technologies, technology nodes and fabrication approaches. We present DESTINY, a tool for modeling 2D/3D memories designed using SRAM, resistive RAM (ReRAM, spin transfer torque RAM (STT-RAM, phase change RAM (PCM and embedded DRAM (eDRAM and 2D memories designed using spin orbit torque RAM (SOT-RAM, domain wall memory (DWM and Flash memory. In addition to single-level cell (SLC designs for all of these memories, DESTINY also supports modeling MLC designs for NVMs. We have extensively validated DESTINY against commercial and research prototypes of these memories. DESTINY is very useful for performing design-space exploration across several dimensions, such as optimizing for a target (e.g., latency, area or energy-delay product for a given memory technology, choosing the suitable memory technology or fabrication method (i.e., 2D v/s 3D for a given optimization target, etc. We believe that DESTINY will boost studies of next-generation memory architectures used in systems ranging from mobile devices to extreme-scale supercomputers. The latest source-code of DESTINY is available from the following git repository: https://bitbucket.org/sparshmittal/destinyv2.

  15. From MEMRISTOR to MEMImpedance device

    Energy Technology Data Exchange (ETDEWEB)

    Wakrim, T. [Univ. Grenoble Alpes, LTM (CEA-LETI/Minatec), 38000 Grenoble (France); Univ. Grenoble Alpes, G2Elab, F-38000 Grenoble (France); Vallée, C., E-mail: christophe.vallee@cea.fr; Gonon, P.; Mannequin, C. [Univ. Grenoble Alpes, LTM (CEA-LETI/Minatec), 38000 Grenoble (France); Sylvestre, A. [Univ. Grenoble Alpes, G2Elab, F-38000 Grenoble (France)

    2016-02-01

    The behavior of the capacitance switching of HfO{sub 2} Resistive non-volatile Memories is investigated in view of realizing a MEMImpedance (MEM-Z) device. In such a Metal Insulator Metal structure, the impedance value can be tuned by the adjustment of both resistance and capacitance values. We observe a strong variation of capacitance from positive to negative values in a single layer Metal Insulator Metal device made of HfO{sub 2} deposited by Atomic Layer Deposition, but unfortunately no memory effect is observed. However, in the case of a two layer structure, a device has been obtained with a memory effect where both resistance and capacitance values can be tuned simultaneously, with a variation of capacitance down to negative values to get an inductive behavior. Negative capacitance values are observed for voltage values near SET voltage. A schematic model based on shaped oxygen vacancy density is proposed to account for this capacitance variation. The oxygen vacancies can be either isolated or connected in the bulk of the oxide.

  16. Multi-step resistive switching behavior of Li-doped ZnO resistance random access memory device controlled by compliance current

    Science.gov (United States)

    Lin, Chun-Cheng; Tang, Jian-Fu; Su, Hsiu-Hsien; Hong, Cheng-Shong; Huang, Chih-Yu; Chu, Sheng-Yuan

    2016-06-01

    The multi-step resistive switching (RS) behavior of a unipolar Pt/Li0.06Zn0.94O/Pt resistive random access memory (RRAM) device is investigated. It is found that the RRAM device exhibits normal, 2-, 3-, and 4-step RESET behaviors under different compliance currents. The transport mechanism within the device is investigated by means of current-voltage curves, in-situ transmission electron microscopy, and electrochemical impedance spectroscopy. It is shown that the ion transport mechanism is dominated by Ohmic behavior under low electric fields and the Poole-Frenkel emission effect (normal RS behavior) or Li+ ion diffusion (2-, 3-, and 4-step RESET behaviors) under high electric fields.

  17. On the Nature of Dependence in the Volatility of US Stock Returns

    OpenAIRE

    Barnes, Michelle L.

    1998-01-01

    Long memory in the volatility of individual return series and in the volatility of equal-weighted portfolios constituted by the individual return series is analyzed to see if the memory characteristic of the volatility representation is correlated with the portfolio characteristics of size, standard deviation of returns, and firm's beta.

  18. Multilevel non-volatile data storage utilizing common current hysteresis of networked single walled carbon nanotubes

    Science.gov (United States)

    Hwang, Ihn; Wang, Wei; Hwang, Sun Kak; Cho, Sung Hwan; Kim, Kang Lib; Jeong, Beomjin; Huh, June; Park, Cheolmin

    2016-05-01

    The characteristic source-drain current hysteresis frequently observed in field-effect transistors with networked single walled carbon-nanotube (NSWNT) channels is problematic for the reliable switching and sensing performance of devices. But the two distinct current states of the hysteresis curve at a zero gate voltage can be useful for memory applications. In this work, we demonstrate a novel non-volatile transistor memory with solution-processed NSWNTs which are suitable for multilevel data programming and reading. A polymer passivation layer with a small amount of water employed on the top of the NSWNT channel serves as an efficient gate voltage dependent charge trapping and de-trapping site. A systematic investigation evidences that the water mixed in a polymer passivation solution is critical for reliable non-volatile memory operation. The optimized device is air-stable and temperature-resistive up to 80 °C and exhibits excellent non-volatile memory performance with an on/off current ratio greater than 104, a switching time less than 100 ms, data retention longer than 4000 s, and write/read endurance over 100 cycles. Furthermore, the gate voltage dependent charge injection mediated by water in the passivation layer allowed for multilevel operation of our memory in which 4 distinct current states were programmed repetitively and preserved over a long time period.The characteristic source-drain current hysteresis frequently observed in field-effect transistors with networked single walled carbon-nanotube (NSWNT) channels is problematic for the reliable switching and sensing performance of devices. But the two distinct current states of the hysteresis curve at a zero gate voltage can be useful for memory applications. In this work, we demonstrate a novel non-volatile transistor memory with solution-processed NSWNTs which are suitable for multilevel data programming and reading. A polymer passivation layer with a small amount of water employed on the top of the

  19. Observation of Resistive Switching Memory by Reducing Device Size in a New Cr/CrOx/TiOx/TiN Structure

    Institute of Scientific and Technical Information of China (English)

    Debanjan Jana; Subhranu Samanta; Sourav Roy; Yu Feng Lin; Siddheswar Maikap

    2015-01-01

    The resistive switching memory characteristics of 100 randomly measured devices were observed by reducing device size in a Cr/CrOx/TiOx/TiN structure for the first time. Transmission electron microscope image confirmed a via-hole size of 0.4 lm. A 3-nm-thick amorphous TiOx with 4-nm-thick polycrystalline CrOx layer was observed. A small 0.4-lm device shows reversible resistive switching at a current compliance of 300 lA as compared to other larger size devices (1–8 lm) owing to reduction of leakage current through the TiOx layer. Good device-to-device uniformity with a yield of [85%has been clarified by weibull distribution owing to higher slope/shape factor. The switching mechanism is based on oxygen vacancy migration from the CrOx layer and filament formation/rupture in the TiOx layer. Long read pulse endurance of [105 cycles, good data retention of 6 h, and a program/erase speed of 1 ls pulse width have been obtained.

  20. linical Effect Observation of MCu Memory Alloy Intrauterine Device%放置MCu记忆合金宫内节育器临床效果观察

    Institute of Scientific and Technical Information of China (English)

    王玲; 张蕊

    2016-01-01

    目的:探讨观察MCu记忆合金宫内节育器临床使用情况。方法方便选择于2012年2月—2014年12月在山东省烟台市计划生育指导中心自愿放置MCu记忆合金宫内节育器的受试者400例,进行临床效果观察。结果 MCu记忆合金宫内节育器,置器18个月MCuIUD避孕率为99.75%;不良反应发生率3个月时13.5%,18个月后降至0%。累计移位率1.25%,脱落率0.25%;累计续用率为96.25%。结论 MCu记忆合金宫内节育器,避孕有效率高、因症取出及不良反应发生率低,操作便捷,在临床使用中安全高效值得推广使用。%Objective To investigate the clinical use of MCu memory alloy intrauterine device. Methods Convenient selec-tion 400 cases of MCu memory alloy intrauterine device in Yantai City, Shandong Province, family planning guidance center from February 2012 to December 2014 years old were selected, and the clinical effect was observed. Results MCu memory alloy intrauterine device, the device for 18 months MCuIUD contraceptive rate was 99.75%; the incidence of adverse reac-tions was 3 months, 18, 13.5% months after the 0%. The cumulative displacement rate was 1.25%, and the shedding rate was 0.25%. The cumulative rate was 96.25%. Conclusion MCu memory alloy intrauterine device, the effective rate of con-traception, and the incidence of adverse drug reaction rate is low, the operation is convenient, safe and effective in clinical use is worthy of popularization and use.

  1. Tantalum oxide nanoscale resistive switching devices: TEM/EELS study (Presentation Recording)

    Science.gov (United States)

    Norris, Kate J.; Zhang, Jiaming; Merced-Grafals, Emmanuelle; Musunuru, Srinitya; Zhang, Max; Samuels, Katy; Yang, Jianhua J.; Kobayashi, Nobuhiko P.

    2015-08-01

    The field of non-volatile memory devices has been boosted by resistive switching, a reversible change in electrical resistance of a dielectric layer through the application of a voltage potential. Tantalum oxide being one of the leading candidates for the dielectric component of resistance switching devices was investigated in this study. 55nm TaOx devices in all states were compared through cross sectional TEM techniques including HRTEM, EELS, and EFTEM and will be discussed in this presentation. Based on the chemical and physical features found in the cross sectioned nanodevices we will discuss the switching mechanism of these nanoscale devices.

  2. Investigation of Hafnium oxide/Copper resistive memory for advanced encryption applications

    Science.gov (United States)

    Briggs, Benjamin D.

    The Advanced Encryption Standard (AES) is a widely used encryption algorithm to protect data and communications in today's digital age. Modern AES CMOS implementations require large amounts of dedicated logic and must be tuned for either performance or power consumption. A high throughput, low power, and low die area AES implementation is required in the growing mobile sector. An emerging non-volatile memory device known as resistive memory (ReRAM) is a simple metal-insulator-metal capacitor device structure with the ability to switch between two stable resistance states. Currently, ReRAM is targeted as a non-volatile memory replacement technology to eventually replace flash. Its advantages over flash include ease of fabrication, speed, and lower power consumption. In addition to memory, ReRAM can also be used in advanced logic implementations given its purely resistive behavior. The combination of a new non-volatile memory element ReRAM along with high performance, low power CMOS opens new avenues for logic implementations. This dissertation will cover the design and process implementation of a ReRAM-CMOS hybrid circuit, built using IBM's 10LPe process, for the improvement of hardware AES implementations. Further the device characteristics of ReRAM, specifically the HfO2/Cu memory system, and mechanisms for operation are not fully correlated. Of particular interest to this work is the role of material properties such as the stoichiometry, crystallinity, and doping of the HfO2 layer and their effect on the switching characteristics of resistive memory. Material properties were varied by a combination of atomic layer deposition and reactive sputtering of the HfO2 layer. Several studies will be discussed on how the above mentioned material properties influence switching parameters, and change the underlying physics of device operation.

  3. Cache Optimization Approaches of Emerging Non-Volatile Memory Architecture:A Survey%新型非易失性存储器架构的缓存优化方法综述

    Institute of Scientific and Technical Information of China (English)

    何炎祥; 沈凡凡; 张军; 江南; 李清安; 李建华

    2015-01-01

    随着半导体工艺的发展,处理器集成的片上缓存越来越大,传统存储器件的漏电功耗问题日益严峻,如何设计高能效的片上存储架构已成为重要挑战.为解决这些问题,国内外研究者讨论了大量的新型非易失性存储技术,它们具有非易失性、低功耗和高存储密度等优良特性.为探索spin-transfer torque RAM (STT-RAM),phase change memory (PCM),resistive RAM (RRAM)和domain-wall memory(DWM)四种新型非易失性存储器(non-volatile memory,NVM)架构缓存的方法,对比了其与传统存储器件的物理特性,讨论了其架构缓存的优缺点和适用性,重点分类并总结了其架构缓存的优化方法和策略,分析了其中针对新型非易失性存储器写功耗高、写寿命有限和写延迟长等缺点所作出的关键优化技术,最后探讨了新型非易失性存储器件在未来缓存优化中可能的研究方向.

  4. Inadvertently programmed bits in Samsung 128 Mbit flash devices: a flaky investigation

    Science.gov (United States)

    Swift, G.

    2002-01-01

    JPL's X2000 avionics design pioneers new territory by specifying a non-volatile memory (NVM) board based on flash memories. The Samsung 128Mb device chosen was found to demonstrate bit errors (mostly program disturbs) and block-erase failures that increase with cycling. Low temperature, certain pseudo- random patterns, and, probably, higher bias increase the observable bit errors. An experiment was conducted to determine the wearout dependence of the bit errors to 100k cycles at cold temperature using flight-lot devices (some pre-irradiated). The results show an exponential growth rate, a wide part-to-part variation, and some annealing behavior.

  5. Inadvertently programmed bits in Samsung 128 Mbit flash devices: a flaky investigation

    Science.gov (United States)

    Swift, G.

    2002-01-01

    JPL's X2000 avionics design pioneers new territory by specifying a non-volatile memory (NVM) board based on flash memories. The Samsung 128Mb device chosen was found to demonstrate bit errors (mostly program disturbs) and block-erase failures that increase with cycling. Low temperature, certain pseudo- random patterns, and, probably, higher bias increase the observable bit errors. An experiment was conducted to determine the wearout dependence of the bit errors to 100k cycles at cold temperature using flight-lot devices (some pre-irradiated). The results show an exponential growth rate, a wide part-to-part variation, and some annealing behavior.

  6. Fabrication of ultrahigh density metal-cell-metal crossbar memory devices with only two cycles of lithography and dry-etch procedures

    KAUST Repository

    Zong, Baoyu

    2013-05-20

    A novel approach to the fabrication of metal-cell-metal trilayer memory devices was demonstrated by using only two cycles of lithography and dry-etch procedures. The fabricated ultrahigh density crossbar devices can be scaled down to ≤70 nm in half-pitch without alignment issues. Depending on the different dry-etch mechanisms in transferring high and low density nanopatterns, suitable dry-etch angles and methods are studied for the transfer of high density nanopatterns. Some novel process methods have also been developed to eliminate the sidewall and other conversion obstacles for obtaining high density of uniform metallic nanopatterns. With these methods, ultrahigh density trilayer crossbar devices (∼2 × 1010 bit cm-2-kilobit electronic memory), which are composed of built-in practical magnetoresistive nanocells, have been achieved. This scalable process that we have developed provides the relevant industries with a cheap means to commercially fabricate three-dimensional high density metal-cell-metal nanodevices. © 2013 IOP Publishing Ltd.

  7. CMOS-compatible spintronic devices: a review

    Science.gov (United States)

    Makarov, Alexander; Windbacher, Thomas; Sverdlov, Viktor; Selberherr, Siegfried

    2016-11-01

    For many decades CMOS devices have been successfully scaled down to achieve higher speed and increased performance of integrated circuits at lower cost. Today’s charge-based CMOS electronics encounters two major challenges: power dissipation and variability. Spintronics is a rapidly evolving research and development field, which offers a potential solution to these issues by introducing novel ‘more than Moore’ devices. Spin-based magnetoresistive random-access memory (MRAM) is already recognized as one of the most promising candidates for future universal memory. Magnetic tunnel junctions, the main elements of MRAM cells, can also be used to build logic-in-memory circuits with non-volatile storage elements on top of CMOS logic circuits, as well as versatile compact on-chip oscillators with low power consumption. We give an overview of CMOS-compatible spintronics applications. First, we present a brief introduction to the physical background considering such effects as magnetoresistance, spin-transfer torque (STT), spin Hall effect, and magnetoelectric effects. We continue with a comprehensive review of the state-of-the-art spintronic devices for memory applications (STT-MRAM, domain wall-motion MRAM, and spin-orbit torque MRAM), oscillators (spin torque oscillators and spin Hall nano-oscillators), logic (logic-in-memory, all-spin logic, and buffered magnetic logic gate grid), sensors, and random number generators. Devices with different types of resistivity switching are analyzed and compared, with their advantages highlighted and challenges revealed. CMOS-compatible spintronic devices are demonstrated beginning with predictive simulations, proceeding to their experimental confirmation and realization, and finalized by the current status of application in modern integrated systems and circuits. We conclude the review with an outlook, where we share our vision on the future applications of the prospective devices in the area.

  8. CMOS Interface Circuits for Spin Tunneling Junction Based Magnetic Random Access Memories

    Energy Technology Data Exchange (ETDEWEB)

    Ganesh Saripalli

    2002-12-31

    Magneto resistive memories (MRAM) are non-volatile memories which use magnetic instead of electrical structures to store data. These memories, apart from being non-volatile, offer a possibility to achieve densities better than DRAMs and speeds faster than SRAMs. MRAMs could potentially replace all computer memory RAM technologies in use today, leading to future applications like instan-on computers and longer battery life for pervasive devices. Such rapid development was made possible due to the recent discovery of large magnetoresistance in Spin tunneling junction devices. Spin tunneling junctions (STJ) are composite structures consisting of a thin insulating layer sandwiched between two magnetic layers. This thesis research is targeted towards these spin tunneling junction based Magnetic memories. In any memory, some kind of an interface circuit is needed to read the logic states. In this thesis, four such circuits are proposed and designed for Magnetic memories (MRAM). These circuits interface to the Spin tunneling junctions and act as sense amplifiers to read their magnetic states. The physical structure and functional characteristics of these circuits are discussed in this thesis. Mismatch effects on the circuits and proper design techniques are also presented. To demonstrate the functionality of these interface structures, test circuits were designed and fabricated in TSMC 0.35{micro} CMOS process. Also circuits to characterize the process mismatches were fabricated and tested. These results were then used in Matlab programs to aid in design process and to predict interface circuit's yields.

  9. CMOS Interface Circuits for Spin Tunneling Junction Based Magnetic Random Access Memories

    Energy Technology Data Exchange (ETDEWEB)

    Saripalli, Ganesh [Iowa State Univ., Ames, IA (United States)

    2002-01-01

    Magneto resistive memories (MRAM) are non-volatile memories which use magnetic instead of electrical structures to store data. These memories, apart from being non-volatile, offer a possibility to achieve densities better than DRAMs and speeds faster than SRAMs. MRAMs could potentially replace all computer memory RAM technologies in use today, leading to future applications like instan-on computers and longer battery life for pervasive devices. Such rapid development was made possible due to the recent discovery of large magnetoresistance in Spin tunneling junction devices. Spin tunneling junctions (STJ) are composite structures consisting of a thin insulating layer sandwiched between two magnetic layers. This thesis research is targeted towards these spin tunneling junction based Magnetic memories. In any memory, some kind of an interface circuit is needed to read the logic states. In this thesis, four such circuits are proposed and designed for Magnetic memories (MRAM). These circuits interface to the Spin tunneling junctions and act as sense amplifiers to read their magnetic states. The physical structure and functional characteristics of these circuits are discussed in this thesis. Mismatch effects on the circuits and proper design techniques are also presented. To demonstrate the functionality of these interface structures, test circuits were designed and fabricated in TSMC 0.35μ CMOS process. Also circuits to characterize the process mismatches were fabricated and tested. These results were then used in Matlab programs to aid in design process and to predict interface circuit's yields.

  10. A multiscale simulation technique for molecular electronics: design of a directed self-assembled molecular n-bit shift register memory device.

    Science.gov (United States)

    Lambropoulos, Nicholas A; Reimers, Jeffrey R; Crossley, Maxwell J; Hush, Noel S; Silverbrook, Kia

    2013-12-20

    A general method useful in molecular electronics design is developed that integrates modelling on the nano-scale (using quantum-chemical software) and on the micro-scale (using finite-element methods). It is applied to the design of an n-bit shift register memory that could conceivably be built using accessible technologies. To achieve this, the entire complex structure of the device would be built to atomic precision using feedback-controlled lithography to provide atomic-level control of silicon devices, controlled wet-chemical synthesis of molecular insulating pillars above the silicon, and controlled wet-chemical self-assembly of modular molecular devices to these pillars that connect to external metal electrodes (leads). The shift register consists of n connected cells that read data from an input electrode, pass it sequentially between the cells under the control of two external clock electrodes, and deliver it finally to an output device. The proposed cells are trimeric oligoporphyrin units whose internal states are manipulated to provide functionality, covalently connected to other cells via dipeptide linkages. Signals from the clock electrodes are conveyed by oligoporphyrin molecular wires, and μ-oxo porphyrin insulating columns are used as the supporting pillars. The developed multiscale modelling technique is applied to determine the characteristics of this molecular device, with in particular utilization of the inverted region for molecular electron-transfer processes shown to facilitate latching and control using exceptionally low energy costs per logic operation compared to standard CMOS shift register technology.

  11. Effect of CuPc layer insertion on the memory performance of CdS nanocomposite diodes

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, S.K., E-mail: surya@pu.ac.in; Kaur, Ramneek; Jyoti

    2016-09-15

    Highlights: • CdS nanocomposite as an active layer investigated for memory device application. • Effect of copper phthalocyanine layer insertion on the memory performance studied. • Bipolar switching behaviour with high ON/OFF ratio ∼1.4 × 10{sup 4}. • Series resistance and interface states dominate the electrical properties of the device. - Abstract: In the present work, semiconductor diodes with CdS nanocomposite as an active layer have been fabricated and investigated for memory device applications. The effect of copper phthalocyanine (CuPc) layer insertion between the bottom electrode and CdS nanocomposite has been studied. I–V characteristics show electrical hysteresis behaviour vital for memory storage application. The as-fabricated devices exhibit bipolar switching behaviour with OFF to ON state transition at positive bias and vice versa. Device with CuPc layer exhibits I{sub ON}/I{sub OFF} ratio ∼ 1.4 × 10{sup 4}. Possible conduction mechanism has been described on the basis of theoretical current conduction models. The frequency dispersion capacitance, series resistance and conductance of the devices have been studied and discussed. At low frequency, the series resistance and the interface states dominate the electrical properties of the device. The results indicate that the multilayered devices open up the possibility of new generation non-volatile memory devices with low cost, high density and stability.

  12. The roles of the dielectric constant and the relative level of conduction band of high-k composite with Si in improving the memory performance of charge-trapping memory devices

    Directory of Open Access Journals (Sweden)

    Jianxin Lu

    2014-11-01

    Full Text Available The memory structures Pt/Al2O3/(TiO2x(Al2O31−x/Al2O3/p-Si(nominal composition x = 0.05, 0.50 and 0.70 were fabricated by using rf-magnetron sputtering and atomic layer deposition techniques, in which the dielectric constant and the bottom of the conduction band of the high-k composite (TiO2x(Al2O31−x were adjusted by controlling the partial composition of Al2O3. With the largest dielectric constant and the lowest deviation from the bottom of the conduction band of Si, (TiO20.7(Al2O30.3 memory devices show the largest memory window of 7.54 V, the fast programming/erasing speed and excellent endurance and retention characteristics, which were ascribed to the special structural design, proper combination of dielectric constant and band alignment in the high-k composite (TiO20.7(Al2O30.3.

  13. Investigating the Temperature Effects on ZnO, TiO2, WO3 and HfO2 Based Resistive Random Access Memory (RRAM Devices

    Directory of Open Access Journals (Sweden)

    T.D. Dongale

    2016-11-01

    Full Text Available In this paper, we report the effect of filament radius and filament resistivity on the ZnO, TiO2, WO3 and HfO2 based Resistive Random Access Memory (RRAM devices. We resort to the thermal reaction model of RRAM for the present analysis. The results substantiate decrease in saturated temperature with increase in the radius and resistivity of filament for the investigated RRAM devices. Moreover, a sudden change in the saturated temperature at a lower value of filament radius and resistivity is observed as against the steady change at the medium and higher value of the filament radius and resistivity. Results confirm the dependence of saturated temperature on the filament size and resistivity in RRAM.

  14. Carrier transport mechanisms of bistable memory devices fabricated utilizing core-shell CdSe/ZnSe quantum-dot/multi-walled carbon nanotube hybrid nanocomposites

    Science.gov (United States)

    Li, Fushan; Ick Son, Dong; Kim, Tae Whan; Ryu, Euidock; Kim, Sang Wook

    2009-02-01

    Transmission electron microscopy images showed that conjugation between single core-shell CdSe/ZnSe quantum dots (QDs) and oxidized multi-walled carbon nanotubes (MWCNTs) was achieved through the complexation reaction. Current-voltage (I-V) measurements on Al/CdSe:MWCNT conjugated nanocomposite/indium-tin-oxide devices at 300 K showed that the on/off ratio of the current bistability was as large as about 104, which was significantly increased due to an enhancement of the carrier transfer efficiency between the CdSe/ZnSe QDs and the MWCNTs. Carrier transport mechanisms of the bistable memory devices fabricated utilizing CdSe/ZnSe QD/MWCNT hybrid nanocomposite are described on the basis of the I-V results.

  15. Polarity reversion of the operation mode of HfO2-based resistive random access memory devices by inserting Hf metal layer.

    Science.gov (United States)

    Peng, Ching-Shiang; Chang, Wen-Yuan; Lin, Ming-Ho; Chen, Wei-Su; Chen, Frederick; Tsai, Ming-Jinn

    2013-03-01

    The reversion of polarity within bipolar resistive switching operation occurs in Pt/HfO2/TiN and Pt/Hf/HfO2/TiN resistive random access memory devices. This reversion of voltage polarity is the result of interface generation which induces a conduction mechanism transformation from Poole-Frenkel emission to space charge limited current mechanism. To prove the reversion of polarity, this study uses curve fitting of I-V relations to verify the conduction mechanism theoretically and physical analysis to verify the oxygen ion distribution practically. The proposed Pt/Hf/HfO2/TiN devices exhibit good resistive switching characteristics, such as good uniformity, low voltage operation, robust endurance (10(3) dc sweep), and long retention (3 x 10(4) s at 85 degrees C).

  16. Direct formation of gold nanoparticles on substrates using a novel ZnO sacrificial templated-growth hydrothermal approach and their properties in organic memory device

    Science.gov (United States)

    Goh, Lean Poh; Razak, Khairunisak Abdul; Ridhuan, Nur Syafinaz; Cheong, Kuan Yew; Ooi, Poh Choon; Aw, Kean Chin

    2012-10-01

    This study describes a novel fabrication technique to grow gold nanoparticles (AuNPs) directly on seeded ZnO sacrificial template/polymethylsilsesquioxanes (PMSSQ)/Si using low-temperature hydrothermal reaction at 80°C for 4 h. The effect of non-annealing and various annealing temperatures, 200°C, 300°C, and 400°C, of the ZnO-seeded template on AuNP size and distribution was systematically studied. Another PMMSQ layer was spin-coated on AuNPs to study the memory properties of organic insulator-embedded AuNPs. Well-distributed and controllable AuNP sizes were successfully grown directly on the substrate, as observed using a field emission scanning electron microscope followed by an elemental analysis study. A phase analysis study confirmed that the ZnO sacrificial template was eliminated during the hydrothermal reaction. The AuNP formation mechanism using this hydrothermal reaction approach was proposed. In this study, the AuNPs were charge-trapped sites and showed excellent memory effects when embedded in PMSSQ. Optimum memory properties of PMMSQ-embedded AuNPs were obtained for AuNPs synthesized on a seeded ZnO template annealed at 300°C, with 54 electrons trapped per AuNP and excellent current-voltage response between an erased and programmed device.

  17. Modulation of surface trap induced resistive switching by electrode annealing in individual PbS micro/nanowire-based devices for resistance random access memory.

    Science.gov (United States)

    Zheng, Jianping; Cheng, Baochang; Wu, Fuzhang; Su, Xiaohui; Xiao, Yanhe; Guo, Rui; Lei, Shuijin

    2014-12-10

    Bipolar resistive switching (RS) devices are commonly believed as a promising candidate for next generation nonvolatile resistance random access memory (RRAM). Here, two-terminal devices based on individual PbS micro/nanowires with Ag electrodes are constructed, whose electrical transport depends strongly on the abundant surface and bulk trap states in micro/nanostructures. The surface trap states can be filled/emptied effectively at negative/positive bias voltage, respectively, and the corresponding rise/fall of the Fermi level induces a variation in a degenerate/nondegenerate state, resulting in low/high resistance. Moreover, the filling/emptying of trap states can be utilized as RRAM. After annealing, the surface trap state can almost be eliminated completely; while most of the bulk trap states can still remain. In the devices unannealed and annealed at both ends, therefore, the symmetrical back-to-back Fowler-Nordheim tunneling with large ON/OFF resistance ratio and Poole-Frenkel emission with poor hysteresis can be observed under cyclic sweep voltage, respectively. However, a typical bipolar RS behavior can be observed effectively in the devices annealed at one end. The acquirement of bipolar RS and nonvolatile RRAM by the modulation of electrode annealing demonstrates the abundant trap states in micro/nanomaterials will be advantageous to the development of new type electronic components.

  18. Multilevel Resistance Programming in Conductive Bridge Resistive Memory

    Science.gov (United States)

    Mahalanabis, Debayan

    This work focuses on the existence of multiple resistance states in a type of emerging non-volatile resistive memory device known commonly as Programmable Metallization Cell (PMC) or Conductive Bridge Random Access Memory (CBRAM), which can be important for applications such as multi-bit memory as well as non-volatile logic and neuromorphic computing. First, experimental data from small signal, quasi-static and pulsed mode electrical characterization of such devices are presented which clearly demonstrate the inherent multi-level resistance programmability property in CBRAM devices. A physics based analytical CBRAM compact model is then presented which simulates the ion-transport dynamics and filamentary growth mechanism that causes resistance change in such devices. Simulation results from the model are fitted to experimental dynamic resistance switching characteristics. The model designed using Verilog-a language is computation-efficient and can be integrated with industry standard circuit simulation tools for design and analysis of hybrid circuits involving both CMOS and CBRAM devices. Three main circuit applications for CBRAM devices are explored in this work. Firstly, the susceptibility of CBRAM memory arrays to single event induced upsets is analyzed via compact model simulation and experimental heavy ion testing data that show possibility of both high resistance to low resistance and low resistance to high resistance transitions due to ion strikes. Next, a non-volatile sense amplifier based flip-flop architecture is proposed which can help make leakage power consumption negligible by allowing complete shutdown of power supply while retaining its output data in CBRAM devices. Reliability and energy consumption of the flip-flop circuit for different CBRAM low resistance levels and supply voltage values are analyzed and compared to CMOS designs. Possible extension of this architecture for threshold logic function computation using the CBRAM devices as re

  19. Unique device operations by combining optical-memory effect and electrical-gate modulation in a photochromism-based dual-gate transistor.

    Science.gov (United States)

    Ishiguro, Yasushi; Hayakawa, Ryoma; Yasuda, Takeshi; Chikyow, Toyohiro; Wakayama, Yutaka

    2013-10-09

    We demonstrate a new device that combines a light-field effect and an electrical-gate effect to control the drain current in a dual-gate transistor. We used two organic layers, photochromic spiropyran (SP)-doped poly(triarylamine) (PTAA) and pristine PTAA, as top and bottom channels, respectively, connected to common source and drain electrodes. The application of voltage to the top and bottom gates modulated the drain current through each layer independently. UV irradiation suppressed the drain current through the top channel. The suppressed current was then maintained even after the UV light was turned off because of an optical memory effect induced by photoisomerization of SP. In contrast, UV irradiation did not change the drain current in the bottom channel. Our dual-gate transistor thus has two organic channels with distinct photosensitivities: an optically active SP-PTAA film and an optically inactive PTAA film. This device configuration allows multi-level switching via top- and bottom-gate electrical fields with an optical-memory effect.

  20. Formation of a Mental Abacus for Computation and Its Use as a Memory Device for Digits: A Developmental Study.

    Science.gov (United States)

    Hatano, Giyoo; And Others

    1987-01-01

    Examined whether representational changes in digit memory are functions of children's expertise in mental abacus operation when abacus operators reproduced series of digits forward or backward. Found skilled operators equally facile with forward and backward reproduction, but novices slower going backward. Suggests advanced operators apply their…

  1. Room-temperature fabricated, fully transparent resistive memory based on ITO/CeO2/ITO structure for RRAM applications

    Science.gov (United States)

    Ismail, Muhammad; Rana, Anwar Manzoor; Talib, Ijaz; Tsai, Tsung-Ling; Chand, Umesh; Ahmed, Ejaz; Nadeem, Muhammad Younus; Aziz, Abdul; Shah, Nazar Abbas; Hussain, Muhammad

    2015-01-01

    Fully transparent resistive random access memory (TRRAM) device based on CeO2 as active layer using indium-tin-oxide (ITO) electrodes was fabricated on glass substrate. The ITO/CeO2/ITO memory device shows 81% transmission of visible light, optical band gap energy of 4.05 eV, and exhibits reliable bipolar resistive switching behavior. X-ray diffraction of CeO2 thin films demonstrated a weak polycrystalline phase. The low field conduction is dominated by Ohmic type while Poole-Frenkel effect is responsible for conduction in the high field region. The device reliability investigations, such as data retention (over 104 s) under applied stress and endurance tests conducted at room temperature and 85 °C show potential of our TRRAM devices for future non-volatile memory applications.

  2. Pricing Volatility Referenced Assets

    Directory of Open Access Journals (Sweden)

    Alan De Genaro Dario

    2006-12-01

    Full Text Available Volatility swaps are contingent claims on future realized volatility. Variance swaps are similar instruments on future realized variance, the square of future realized volatility. Unlike a plain vanilla option, whose volatility exposure is contaminated by its asset price dependence, volatility and variance swaps provide a pure exposure to volatility alone. This article discusses the risk-neutral valuation of volatility and variance swaps based on the framework outlined in the Heston (1993 stochastic volatility model. Additionally, the Heston (1993 model is calibrated for foreign currency options traded at BMF and its parameters are used to price swaps on volatility and variance of the BRL / USD exchange rate.

  3. Can a nickel-titanium memory-shape device serve as a substitute for the stapler in gastrointestinal anastomosis? A systematic review and meta-analysis.

    Science.gov (United States)

    Li, Ning-Ning; Zhao, Wen-Tao; Wu, Xiao-Ting

    2016-03-01

    Recently, a nickel-titanium (NiTi) memory-shape device has been successfully used in gastrointestinal anastomosis. The aim of this study was to investigate the feasibility and safety of the device. Four databases, reference lists, and the World Health Organization International Clinical Trials Registry Platform were systematically searched for randomized controlled trials assessing the clinical efficacy of a NiTi memory-shape device compared with that of a stapler in gastrointestinal or colorectal anastomosis. Seven randomized controlled trials regarding the use of compression anastomosis clips (CACs) were enrolled for meta-analysis. The use of CACs was associated with a significant reduction in hospital duration (mean = -0.88 d; 95% confidence interval [CI], -1.38 to -0.38), the time to flatus (mean = -0.36 d; 95% CI, -0.08 to -0.04), and the start of oral intake (mean = -0.45 d; 95% CI, -0.83 to -0.06), as well as a nonsignificant change in postoperative complications and mortality. These clinical outcomes did not significantly change with the use of compression anastomosis rings. Colonic anastomosis with a CAC is likely to reduce hospital duration, time to flatus, and the start of oral intake without influencing mortality or postoperative complications and may be a safe and preferable choice in colonic anastomosis. Further well-designed trials should be performed to determine the safety and efficacy of the newly developed compression anastomosis ring in both ileocolic and colorectal anastomosis. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Realized volatility and absolute return volatility: a comparison indicating market risk.

    Science.gov (United States)

    Zheng, Zeyu; Qiao, Zhi; Takaishi, Tetsuya; Stanley, H Eugene; Li, Baowen

    2014-01-01

    Measuring volatility in financial markets is a primary challenge in the theory and practice of risk management and is essential when developing investment strategies. Although the vast literature on the topic describes many different models, two nonparametric measurements have emerged and received wide use over the past decade: realized volatility and absolute return volatility. The former is strongly favored in the financial sector and the latter by econophysicists. We examine the memory and clustering features of these two methods and find that both enable strong predictions. We compare the two in detail and find that although realized volatility has a better short-term effect that allows predictions of near-future market behavior, absolute return volatility is easier to calculate and, as a risk indicator, has approximately the same sensitivity as realized volatility. Our detailed empirical analysis yields valuable guidelines for both researchers and market participants because it provides a significantly clearer comparison of the strengths and weaknesses of the two methods.

  5. Ferroelectric switching of poly(vinylidene difluoride-trifluoroethylene) in metal-ferroelectric-semiconductor non-volatile memories with an amorphous oxide semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Gelinck, G. H., E-mail: Gerwin.Gelinck@tno.nl [Holst Centre/TNO, High Tech Campus 31, 5656 AE Eindhoven (Netherlands); Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Breemen, A. J. J. M. van; Cobb, B. [Holst Centre/TNO, High Tech Campus 31, 5656 AE Eindhoven (Netherlands)

    2015-03-02

    Ferroelectric polarization switching of poly(vinylidene difluoride-trifluoroethylene) is investigated in different thin-film device structures, ranging from simple capacitors to dual-gate thin-film transistors (TFT). Indium gallium zinc oxide, a high mobility amorphous oxide material, is used as semiconductor. We find that the ferroelectric can be polarized in both directions in the metal-ferroelectric-semiconductor (MFS) structure and in the dual-gate TFT under certain biasing conditions, but not in the single-gate thin-film transistors. These results disprove the common belief that MFS structures serve as a good model system for ferroelectric polarization switching in thin-film transistors.

  6. Focused ion beam and field-emission microscopy of metallic filaments in memory devices based on thin films of an ambipolar organic compound consisting of oxadiazole, carbazole, and fluorene units

    Science.gov (United States)

    Pearson, Christopher; Bowen, Leon; Lee, Myung Won; Fisher, Alison L.; Linton, Katherine E.; Bryce, Martin R.; Petty, Michael C.

    2013-01-01

    We report on the mechanism of operation of organic thin film resistive memory architectures based on an ambipolar compound consisting of oxadiazole, carbazole, and fluorene units. Cross-sections of the devices have been imaged by electron microscopy both before and after applying a voltage. The micrographs reveal the growth of filaments, with diameters of 50 nm–100 nm, on the metal cathode. We suggest that these are formed by the drift of aluminium ions from the anode and are responsible for the observed switching and negative differential resistance phenomena in the memory devices.

  7. 日志文件系统在嵌入式存储设备上的实现%The Implementation of Journaling File System on Embedded Memory Device

    Institute of Scientific and Technical Information of China (English)

    郑良辰; 孙玉芳

    2002-01-01

    In embedded systems,unexpected power-off often causes the corruption of the file system and the lose of data.It is necessary to develop a special kind of file system to prevent such corruption.As a kind of journaling file system specially for embedded memory devices,JFFS is just the files system we need.In order to make use of JFFS more extensively,Redfiag Software Ltd.Co.has successfully soved the problem about JFFS'''''''' implementation on DiskOnChip,a special kind of embedded memory device.This paper mostly discusses the design of JFFS and its implementation on DiskOnChip.

  8. The origin of polarity dependent switching type in solution processed Pt/TiO2/Pt memory devices

    Science.gov (United States)

    Biju, K. P.

    2015-06-01

    Resistive switching characteristics of sol-gel processed TiO2 thin films are investigated. The influence of polarity of the forming voltage on switching type in Pt/TiO2/Pt stack is investigated. Reliability and stability of the device is significantly improved by choosing a proper voltage polarity on electroforming. The device shows excellent switching properties such as high on/off ratio (> 20), good cycling endurance and long retention (> 104 s) and possible to use multi bit storage has been demonstrated. The switching mechanism is explained by a physical model based on localized generation/recovery of oxygen vacancy defects.

  9. Effect of glycerol on retention time and electrical properties of polymer bistable memory devices based on glycerol-modified PEDOT:PSS.

    Science.gov (United States)

    Park, Boongik; Lee, Junhwan; Kim, Ohyun

    2012-01-01

    The addition of glycerol to Poly(3,4-ethylenedioxythiophene):Poly(styrene sulfonate) (PEDOT:PSS) films affected the bipolar switching characteristics of nonvolatile polymer memory devices (PMDs). Increasing the glycerol/PEDOT:PSS ratio caused increase in the OFF-current of the PMDs, but did not affect the ON-current levels. This result demonstrates that highly-conductive current paths occur in the ON-state. The write-read-erase-read cycle test was operated > 10(5) times. And, the ON-retention time is largely dependent on the glycerol to PEDOT:PSS ratio and annealing temperature. In addition, AFM analysis on the G-PEDOT:PSS films to see how the surface morphology of G-PEDOT:PSS layer influences the retention time properties was carried out.

  10. PLZT block data composers operated in differential phase mode. [lanthanum-modified lead zirconate titanate ceramic device for digital holographic memory

    Science.gov (United States)

    Drake, M. D.; Klingler, D. E.

    1973-01-01

    The use of PLZT ceramics with the 7/65/35 composition in block data composer (BDC) input devices for holographic memory systems has previously been described for operation in the strain biased, scattering, and edge effect modes. A new and promising mode of BDC operation is the differential phase mode in which each element of a matrix array BDC acts as a phase modulator. The phase modulation results from a phase difference in the optical path length between the electrically poled and depoled states of the PLZT. It is shown that a PLZT BDC can be used as a matrix-type phase modulator to record and process digital data by the differential phase mode in a holographic recording/processing system with readout contrast ratios of between 10:1 and 15:1. The differential phase mode has the advantages that strain bias is not required and that the thickness and strain variations in the PLZT are cancelled out.

  11. Uterine perforation in an adolescent using an intrauterine device with memory function: a case report and review of the published work.

    Science.gov (United States)

    Tong, Jin-Yi; Sun, Wen-Chao; Li, Juan; Jin, Mei; Shen, Xiu-Zhen; Zhang, Zhi-Fen

    2015-04-01

    Intrauterine devices (IUD) are the most common method of reversible birth control used worldwide. Adolescents infrequently have uterine perforation caused by IUD, hampering both the diagnosis and treatment. Herein, we report a case of uterine perforation in an 18-year-old primipara after insertion of an IUD that possessed memory function (AiMu MCu). The patient presented with vomiting and abdominal pain after insertion of an AiMu MCu IUD, was treated via laparoscopy and had a full recovery. The present case indicated that uterine perforation caused by an AiMu MCu IUD may occur as a rare complication and that uterine perforation can occur in an adolescent. Clinicians might consider a diagnosis of uterine perforation in an adolescent reporting vomiting and abdominal pain after IUD insertion. Laparoscopy could be a reasonable treatment option for such patients.

  12. Improvement of operational stability in SET states of phase-change-type nonvolatile memory devices using Sb-rich phase of Ge-Sb-Te alloys

    Science.gov (United States)

    Yoon, Sung-Min; Lee, Seung-Yun; Jung, Soon-Won; Park, Young-Sam; Yu, Byoung-Gon

    2009-05-01

    For realizing the next-generation phase-change memories (PCM), it is required to reduce the fluctuation of resistance values in SET state. The Sb-rich phase of GeSbTe was proposed to fulfill the complete crystallization process at each SET programming and the PCM devices were fabricated by using the double-layered phase-change materials composed of GeSbTe and GeSbTe. It was found that the SET resistances and their fluctuation were reduced as the increase of volume ratio of the GeSbTe. We can conclude that the compositional modification into the Sb-rich phase can be a good way for improving the SET performances for the PCM applications.

  13. Robust estimation of nonstationary, fractionally integrated, autoregressive, stochastic volatility

    OpenAIRE

    Mark J. Jensen

    2015-01-01

    Empirical volatility studies have discovered nonstationary, long-memory dynamics in the volatility of the stock market and foreign exchange rates. This highly persistent, infinite variance - but still mean reverting - behavior is commonly found with nonparametric estimates of the fractional differencing parameter d, for financial volatility. In this paper, a fully parametric Bayesian estimator, robust to nonstationarity, is designed for the fractionally integrated, autoregressive, stochastic ...

  14. Reactive ion etching of Si(x)Sb2Te in CF4/Ar plasma for nonvolatile phase-change memory device.

    Science.gov (United States)

    Gu, Yifeng; Song, Sannian; Song, Zhitang; Cheng, Yan; Liu, Xuyan; Du, Xiaofeng; Liu, Bo; Feng, Songlin

    2013-02-01

    Si(x)Sb2Te material system is novel for phase-change random access memory applications. Its properties are more outstanding than the widely used material Ge2Sb2Te5. Etching process is one of the critical steps in the device fabrication. The etching characteristics of phase-change material Si(x)Sb2Te were studied with CF4/Ar gas mixture by a reactive ion etching system. The changes of etching rate, etching profile and surface root-mean-square roughness resulted from variation of the gas-mixing ratio were investigated under constant pressure (50 mTorr) and applying power (200 W). Si0.34Sb2Te is with the highest phase-change speed and the lowest power consumption in the PCRAM memory among these compositions, which means it is the most promising candidate for the PCRAM applications. So the most optimized CF4/Ar gas ratio for Si0.34Sb2Te was studied, the value is 25/25. The etching rate is 155 nm/min, and the selectivity of Si0.34Sb2Te to SiO2 is as high as 3.4 times. Furthermore, the smooth surface was achieved with this optimized gas ratio.

  15. LDRD Final Report - Investigations of the impact of the process integration of deposited magnetic films for magnetic memory technologies on radiation-hardened CMOS devices and circuits - LDRD Project (FY99)

    Energy Technology Data Exchange (ETDEWEB)

    MYERS,DAVID R.; JESSING,JEFFREY R.; SPAHN,OLGA B.; SHANEYFELT,MARTY R.

    2000-01-01

    This project represented a coordinated LLNL-SNL collaboration to investigate the feasibility of developing radiation-hardened magnetic non-volatile memories using giant magnetoresistance (GMR) materials. The intent of this limited-duration study was to investigate whether giant magnetoresistance (GMR) materials similar to those used for magnetic tunnel junctions (MTJs) were process compatible with functioning CMOS circuits. Sandia's work on this project demonstrated that deposition of GMR materials did not affect the operation nor the radiation hardness of Sandia's rad-hard CMOS technology, nor did the integration of GMR materials and exposure to ionizing radiation affect the magnetic properties of the GMR films. Thus, following deposition of GMR films on rad-hard integrated circuits, both the circuits and the films survived ionizing radiation levels consistent with DOE mission requirements. Furthermore, Sandia developed techniques to pattern deposited GMR films without degrading the completed integrated circuits upon which they were deposited. The present feasibility study demonstrated all the necessary processing elements to allow fabrication of the non-volatile memory elements onto an existing CMOS chip, and even allow the use of embedded (on-chip) non-volatile memories for system-on-a-chip applications, even in demanding radiation environments. However, funding agencies DTRA, AIM, and DARPA did not have any funds available to support the required follow-on technology development projects that would have been required to develop functioning prototype circuits, nor were such funds available from LDRD nor from other DOE program funds.

  16. A carrier transport model in the high-resistance state of lead-methylamine iodide-based resistive memory devices

    Directory of Open Access Journals (Sweden)

    Yongwoo Kwon

    2017-08-01

    Full Text Available Methylamine lead iodide (CH3NH3PbI3, which has recently been in the spotlight as a solar cell material, has also recently shown promise for use as an active material in resistive memory cells with ultralow operation voltages, good transparencies, and flexibilities. The material’s defects, which govern its properties, differ vastly depending on the fabrication process. However, the defect chemistry is not yet entirely understood. We have therefore established a macroscopic transport model with defect-related model parameters, such as trap density, trap energy level, and Fermi level, in order to estimate these parameters for fabricated samples based on their electrical data. Our model will serve as an efficient way to analyze the properties of the active material.

  17. Heterogeneous nanometer-scale Joule and Peltier effects in sub-25 nm thin phase change memory devices

    Science.gov (United States)

    Grosse, Kyle L.; Pop, Eric; King, William P.

    2014-09-01

    We measure heterogeneous power dissipation in phase change memory (PCM) films of 11 and 22 nm thin Ge2Sb2Te5 (GST) by scanning Joule expansion microscopy (SJEM), with sub-50 nm spatial and ˜0.2 K temperature resolution. The heterogeneous Joule and Peltier effects are explained using a finite element analysis (FEA) model with a mixture of hexagonal close-packed and face-centered cubic GST phases. Transfer length method measurements and effective media theory calculations yield the GST resistivity, GST-TiW contact resistivity, and crystal fraction of the GST films at different annealing temperatures. Further comparison of SJEM measurements and FEA modeling also predicts the thermopower of thin GST films. These measurements of nanometer-scale Joule, thermoelectric, and interface effects in PCM films could lead to energy-efficient designs of highly scaled PCM technology.

  18. A carrier transport model in the high-resistance state of lead-methylamine iodide-based resistive memory devices

    Science.gov (United States)

    Kwon, Yongwoo; Park, Nayoung; Cha, Pil-Ryung

    2017-08-01

    Methylamine lead iodide (CH3NH3PbI3), which has recently been in the spotlight as a solar cell material, has also recently shown promise for use as an active material in resistive memory cells with ultralow operation voltages, good transparencies, and flexibilities. The material's defects, which govern its properties, differ vastly depending on the fabrication process. However, the defect chemistry is not yet entirely understood. We have therefore established a macroscopic transport model with defect-related model parameters, such as trap density, trap energy level, and Fermi level, in order to estimate these parameters for fabricated samples based on their electrical data. Our model will serve as an efficient way to analyze the properties of the active material.

  19. Low-Programmable-Voltage Nonvolatile Memory Devices Based on Omega-shaped Gate Organic Ferroelectric P(VDF-TrFE) Field Effect Transistors Using p-type Silicon Nanowire Channels

    Institute of Scientific and Technical Information of China (English)

    Ngoc Huynh Van; Jae-Hyun Lee; Dongmok Whang; Dae Joon Kang

    2015-01-01

    A facile approach was demonstrated for fabricating high-performance nonvolatile memory devices based on ferroelectric-gate field effect transistors using a p-type Si nanowire coated with omega-shaped gate organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)). We overcame the interfacial layer problem by incorporating P(VDF-TrFE) as a ferroelectric gate using a low-temperature fabrication process. Our memory devices exhibited excellent memory characteristics with a low programming voltage of ±5 V, a large modulation in channel conductance between ON and OFF states exceeding 105, a long retention time greater than 3 9 104 s, and a high endurance of over 105 programming cycles while maintaining an ION/IOFF ratio higher than 102.

  20. On-site analysis of volatile nitrosamines in food model systems by solid-phase microextraction coupled to a direct extraction device.

    Science.gov (United States)

    Ventanas, S; Ruiz, J

    2006-12-15

    Analysis of nitrosamine (NA) standards in a model system was carried out by extraction using SPME coupled to a direct extraction device (DED) and subsequent GC/MS in selected ion monitoring mode. Gelatine (20%, w/v) systems of a NA standard (10mugL(-1)) were prepared, in order to mimic food protein matrix systems such as meat and meat products, fish and so on. Different SPME fibre coatings were tested Both divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) and carboxen/polydimethylsiloxane (CAR/PDMS) fibres coupled to DED satisfactorily extracted all nine NA included in the studied standard (EPA 8270 nitrosamines mix, Sigma-Aldrich) from the gelatine system at 25 degrees C without any sample manipulation. Values of reproducibility, linearity and limit of detection for each type of fibre are reported. SPME-DED appears as a rapid, non-destructive technique for preliminary screening of the presence of toxic substances such as NA in solid foods.

  1. Enabling universal memory by overcoming the contradictory speed and stability nature of phase-change materials.

    Science.gov (United States)

    Wang, Weijie; Loke, Desmond; Shi, Luping; Zhao, Rong; Yang, Hongxin; Law, Leong-Tat; Ng, Lung-Tat; Lim, Kian-Guan; Yeo, Yee-Chia; Chong, Tow-Chong; Lacaita, Andrea L

    2012-01-01

    The quest for universal memory is driving the rapid development of memories with superior all-round capabilities in non-volatility, high speed, high endurance and low power. Phase-change materials are highly promising in this respect. However, their contradictory speed and stability properties present a key challenge towards this ambition. We reveal that as the device size decreases, the phase-change mechanism changes from the material inherent crystallization mechanism (either nucleation- or growth-dominated), to the hetero-crystallization mechanism, which resulted in a significant increase in PCRAM speeds. Reducing the grain size can further increase the speed of phase-change. Such grain size effect on speed becomes increasingly significant at smaller device sizes. Together with the nano-thermal and electrical effects, fast phase-change, good stability and high endurance can be achieved. These findings lead to a feasible solution to achieve a universal memory.

  2. Memory hierarchy using row-based compression

    Science.gov (United States)

    Loh, Gabriel H.; O'Connor, James M.

    2016-10-25

    A system includes a first memory and a device coupleable to the first memory. The device includes a second memory to cache data from the first memory. The second memory includes a plurality of rows, each row including a corresponding set of compressed data blocks of non-uniform sizes and a corresponding set of tag blocks. Each tag block represents a corresponding compressed data block of the row. The device further includes decompression logic to decompress data blocks accessed from the second memory. The device further includes compression logic to compress data blocks to be stored in the second memory.

  3. Emerging memory technologies design, architecture, and applications

    CERN Document Server

    2014-01-01

    This book explores the design implications of emerging, non-volatile memory (NVM) technologies on future computer memory hierarchy architecture designs. Since NVM technologies combine the speed of SRAM, the density of DRAM, and the non-volatility of Flash memory, they are very attractive as the basis for future universal memories. This book provides a holistic perspective on the topic, covering modeling, design, architecture and applications. The practical information included in this book will enable designers to exploit emerging memory technologies to improve significantly the performance/power/reliability of future, mainstream integrated circuits. • Provides a comprehensive reference on designing modern circuits with emerging, non-volatile memory technologies, such as MRAM and PCRAM; • Explores new design opportunities offered by emerging memory technologies, from a holistic perspective; • Describes topics in technology, modeling, architecture and applications; • Enables circuit designers to ex...

  4. Fabrication of resistive switching memory based on solution processed PMMA-HfO x blended thin films

    Science.gov (United States)

    Lee, Jae-Won; Cho, Won-Ju

    2017-02-01

    In this study, we developed PMMA-HfO x blended resistive random access memory (ReRAM) devices using solution processing to overcome the drawbacks of the individual organic and inorganic materials. Resistive switching behaviors of solution-processed PMMA, PMMA-HfO x , and HfO x film-based ReRAM devices were investigated. The poor electrical characteristic of PMMA and brittle mechanical properties of HfO x can be improved by blending PMMA and HfO x together. The PMMA-HfO x blended ReRAM device exhibited a larger memory window, stable endurance and retention, a lower operation power, and better set/reset voltage distributions. Furthermore, these new systems featured multilevel conduction states at different reset bias for non-volatile multilevel memory applications. Therefore, solution-processed PMMA-HfO x blended films are a promising material for non-volatile memory devices on flexible or wearable electronic systems.

  5. Bipolar spectral associative memories.

    Science.gov (United States)

    Spencer, R G

    2001-01-01

    Nonlinear spectral associative memories are proposed as quantized frequency domain formulations of nonlinear, recurrent associative memories in which volatile network attractors are instantiated by attractor waves. In contrast to conventional associative memories, attractors encoded in the frequency domain by convolution may be viewed as volatile online inputs, rather than nonvolatile, off-line parameters. Spectral memories hold several advantages over conventional associative memories, including decoder/attractor separability and linear scalability, which make them especially well suited for digital communications. Bit patterns may be transmitted over a noisy channel in a spectral attractor and recovered at the receiver by recurrent, spectral decoding. Massive nonlocal connectivity is realized virtually, maintaining high symbol-to-bit ratios while scaling linearly with pattern dimension. For n-bit patterns, autoassociative memories achieve the highest noise immunity, whereas heteroassociative memories offer the added flexibility of achieving various code rates, or degrees of extrinsic redundancy. Due to linear scalability, high noise immunity and use of conventional building blocks, spectral associative memories hold much promise for achieving robust communication systems. Simulations are provided showing bit error rates for various degrees of decoding time, computational oversampling, and signal-to-noise ratio.

  6. Writing to and reading from a nano-scale crossbar memory based on memristors

    Science.gov (United States)

    Vontobel, Pascal O.; Robinett, Warren; Kuekes, Philip J.; Stewart, Duncan R.; Straznicky, Joseph; Williams, R. Stanley

    2009-10-01

    We present a design study for a nano-scale crossbar memory system that uses memristors with symmetrical but highly nonlinear current-voltage characteristics as memory elements. The memory is non-volatile since the memristors retain their state when un-powered. In order to address the nano-wires that make up this nano-scale crossbar, we use two coded demultiplexers implemented using mixed-scale crossbars (in which CMOS-wires cross nano-wires and in which the crosspoint junctions have one-time configurable memristors). This memory system does not utilize the kind of devices (diodes or transistors) that are normally used to isolate the memory cell being written to and read from in conventional memories. Instead, special techniques are introduced to perform the writing and the reading operation reliably by taking advantage of the nonlinearity of the type of memristors used. After discussing both writing and reading strategies for our memory system in general, we focus on a 64 × 64 memory array and present simulation results that show the feasibility of these writing and reading procedures. Besides simulating the case where all device parameters assume exactly their nominal value, we also simulate the much more realistic case where the device parameters stray around their nominal value: we observe a degradation in margins, but writing and reading is still feasible. These simulation results are based on a device model for memristors derived from measurements of fabricated devices in nano-scale crossbars using Pt and Ti nano-wires and using oxygen-depleted TiO2 as the switching material.

  7. Influence of polarity of set voltage on the properties of conductive filaments in NiO based nonvolatile memory device

    Science.gov (United States)

    Yan, Hui-Yu; Li, Zhi-Qing

    2017-03-01

    In this paper, we realize the coexistence of bipolar and unipolar resistive switching (RS) in one Pt-Ir/NiO/TiB1+δ cell. The types of RS are controlled by polarity of set voltage and are free from the current compliance. Based on this coexistence, the set voltage and characters of filaments formed in RS are studied. The results show that the types of filaments also show polarity dependence on the set voltage. The positive set voltage can induce metallic filaments while the negative set voltage can result in semiconductor filaments. It reveals that the distribution of magnitude of set voltage shows abnormal polarity dependence in our devices. The combination the theory of interaction between oxygen vacancy defects and one-carrier impact ionization theory of breakdown account for these results. The influence of filament properties on RS types is also discussed.

  8. The future of memory

    Science.gov (United States)

    Marinella, M.

    In the not too distant future, the traditional memory and storage hierarchy of may be replaced by a single Storage Class Memory (SCM) device integrated on or near the logic processor. Traditional magnetic hard drives, NAND flash, DRAM, and higher level caches (L2 and up) will be replaced with a single high performance memory device. The Storage Class Memory paradigm will require high speed ( 1012), nonvolatility (retention > 10 years), and low switching energies (Technology Roadmap for Semiconductors (ITRS) has recently evaluated several potential candidates SCM technologies, including Resistive (or Redox) RAM, Spin Torque Transfer RAM (STT-MRAM), and phase change memory (PCM). All of these devices show potential well beyond that of current flash technologies and research efforts are underway to improve the endurance, write speeds, and scalabilities to be on-par with DRAM. This progress has interesting implications for space electronics: each of these emerging device technologies show excellent resistance to the types of radiation typically found in space applications. Commercially developed, high density storage class memory-based systems may include a memory that is physically radiation hard, and suitable for space applications without major shielding efforts. This paper reviews the Storage Class Memory concept, emerging memory devices, and possible applicability to radiation hardened electronics for space.

  9. The multivariate supOU stochastic volatility model

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole; Stelzer, Robert

    structure of the volatility, the log returns, as well as their "squares" are discussed in detail. Moreover, we give several examples in which long memory effects occur and study how the model as well as the simple Ornstein-Uhlenbeck type stochastic volatility model behave under linear transformations......Using positive semidefinite supOU (superposition of Ornstein-Uhlenbeck type) processes to describe the volatility, we introduce a multivariate stochastic volatility model for financial data which is capable of modelling long range dependence effects. The finiteness of moments and the second order...

  10. Photochromic transduction layers in organic memory elements.

    Science.gov (United States)

    Shallcross, R Clayton; Zacharias, Philipp; Köhnen, Anne; Körner, Peter O; Maibach, Eduard; Meerholz, Klaus

    2013-01-18

    Photochromic molecules provide an intriguing and relatively untapped alternative to traditional materials utilized in organic memory devices. Here, we review recent progress in the implementation of photochromic molecules in electrically-addressed organic memory devices. Recent results for a lightemitting photochromic organic diode are highlighted in the context of multifunctional devices with the ability to simultaneously operate as multilevel memory, signage and display elements. Furthermore, a set of design rules for successful implementation of photochromic compounds in organic memory devices are suggested.

  11. Dual-functional Memory and Threshold Resistive Switching Based on the Push-Pull Mechanism of Oxygen Ions

    KAUST Repository

    Huang, Yi-Jen

    2016-04-07

    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, we show that 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 (<±1 V) and self-compliance to current up to 50 μA. When it is used for threshold switching, the low threshold current is beneficial for improving the device selectivity. The variation of oxygen distribution measured by energy dispersive X-ray spectroscopy and scanning transmission electron microscopy indicates the formation or rupture of conducting filaments in the device at different resistance states. It is therefore suggested that the push and pull actions of oxygen ions in the amorphous TiOx and polycrystalline TiOx films during the voltage sweep account for the memory switching and threshold switching properties in the device.

  12. Dual-functional Memory and Threshold Resistive Switching Based on the Push-Pull Mechanism of Oxygen Ions

    Science.gov (United States)

    Huang, Yi-Jen; Chao, Shih-Chun; Lien, Der-Hsien; Wen, Cheng-Yen; He-Hau, Jr.; Lee, Si-Chen

    2016-04-01

    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, we show that 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 (compliance to current up to 50 μA. When it is used for threshold switching, the low threshold current is beneficial for improving the device selectivity. The variation of oxygen distribution measured by energy dispersive X-ray spectroscopy and scanning transmission electron microscopy indicates the formation or rupture of conducting filaments in the device at different resistance states. It is therefore suggested that the push and pull actions of oxygen ions in the amorphous TiOx and polycrystalline TiOx films during the voltage sweep account for the memory switching and threshold switching properties in the device.

  13. Impact of graphene and single-layer BN insertion on bipolar resistive switching characteristics in tungsten oxide resistive memory

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jongmin; Kim, Duhwan; Jo, Yongcheol; Han, Jaeseok; Woo, Hyeonseok [Division of Physics and Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Kim, Hyungsang, E-mail: hskim@dongguk.edu [Division of Physics and Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Kim, K.K., E-mail: kkkim@dongguk.edu [Department of Energy and Materials Engineering, Dongguk University, Seoul 100-715 (Korea, Republic of); Hong, J.P. [Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Im, Hyunsik, E-mail: hyunsik7@dongguk.edu [Division of Physics and Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of)

    2015-08-31

    The role of the atomic interface in the resistive switching in Al–WO{sub 3}–Al devices is investigated by inserting metallic graphene or insulating hexagonal BN sheet between the top Al electrode and WO{sub 3} film. Clear reversible bipolar-type resistive switching phenomena were observed, regardless of the interface modification. However, endurance and retention properties were affected by the nature of the interface. While the device containing the graphene interface showed significantly improved performance, another device containing the hexagonal BN sheet showed degraded performance. These experimental findings suggest that atomic configuration of the electrode/oxide interface plays a key role in determining the resistive switching characteristics. - Highlights: • We fabricated WO{sub 3}-based non-volatile memories. • Effects of interface on memory performance were studied using graphene and BN. • The graphene-inserted device showed significantly improved performance.

  14. Correlated memory resistor in epitaxial NdNiO{sub 3} heterostructures with asymmetrical proton concentration

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Chadol; Son, Junwoo, E-mail: jwson@postech.ac.kr [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Heo, Seungyang; Jang, Hyun M. [Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of)

    2016-03-21

    The electronic devices using correlated transition metal oxides are the promising candidates to overcome the limitation of the current electronics due to the rich electronic phases and the extreme sensitivities. Here, we report proton-based resistive switching memory that uses correlated oxides, i.e., epitaxial NdNiO{sub 3} heterostructure with asymmetrical concentration of protons (H{sup +}) to obtain multilevel states. By designing such metal-NdNiO{sub 3}-metal device structures with asymmetrical proton concentration, we demonstrate that the correlated oxides exhibit resistive switching by ionic transport of protons at the metal-hydrogenated NdNiO{sub 3} (H-NNO) interface. This finding will guide the development of energy-efficient switching devices for non-volatile memory and neuromorphic applications.

  15. Stable charge storing in two-dimensional MoS2 nanoflake floating gates for multilevel organic flash memory

    Science.gov (United States)

    Kang, Minji; Kim, Yeong-A.; Yun, Jin-Mun; Khim, Dongyoon; Kim, Jihong; Noh, Yong-Young; Baeg, Kang-Jun; Kim, Dong-Yu

    2014-10-01

    In this study, we investigated chemically exfoliated two-dimensional (2-D) nanoflakes of molybdenum disulfide (MoS2) as charge-storing elements for use in organic multilevel memory devices (of the printed/flexible non-volatile type) based on organic field-effect transistors (OFETs) containing poly(3-hexylthiophene) (P3HT). The metallic MoS2 nanoflakes were exfoliated in 2-methoxyethanol by the lithium intercalation method and were deposited as nano-floating gates between polystyrene and poly(methyl methacrylate), used as bilayered gate dielectrics, by a simple spin-coating and low temperature (102 times, and most importantly, quasi-permanent charge-storing characteristics, i.e., a very long retention time (longer than the technological requirement of commercial memory devices (>10 years)). In addition, we successfully developed multilevel memory cells (2 bits per cell) by controlling the gate bias magnitude.In this study, we investigated chemically exfoliated two-dimensional (2-D) nanoflakes of molybdenum disulfide (MoS2) as charge-storing elements for use in organic multilevel memory devices (of the printed/flexible non-volatile type) based on organic field-effect transistors (OFETs) containing poly(3-hexylthiophene) (P3HT). The metallic MoS2 nanoflakes were exfoliated in 2-methoxyethanol by the lithium intercalation method and were deposited as nano-floating gates between polystyrene and poly(methyl methacrylate), used as bilayered gate dielectrics, by a simple spin-coating and low temperature (102 times, and most importantly, quasi-permanent charge-storing characteristics, i.e., a very long retention time (longer than the technological requirement of commercial memory devices (>10 years)). In addition, we successfully developed multilevel memory cells (2 bits per cell) by controlling the gate bias magnitude. Electronic supplementary information (ESI) available: The memory characteristics with thickness of MoS2 nanoflakes as nano-floating-gate. See DOI: 10.1039/c

  16. Integrating a novel shape memory polymer into surgical meshes to improve device performance during laparoscopic hernia surgery

    Science.gov (United States)

    Zimkowski, Michael M.

    About 600,000 hernia repair surgeries are performed each year. The use of laparoscopic minimally invasive techniques has become increasingly popular in these operations. Use of surgical mesh in hernia repair has shown lower recurrence rates compared to other repair methods. However in many procedures, placement of surgical mesh can be challenging and even complicate the procedure, potentially leading to lengthy operating times. Various techniques have been attempted to improve mesh placement, including use of specialized systems to orient the mesh into a specific shape, with limited success and acceptance. In this work, a programmed novel Shape Memory Polymer (SMP) was integrated into commercially available polyester surgical meshes to add automatic unrolling and tissue conforming functionalities, while preserving the intrinsic structural properties of the original surgical mesh. Tensile testing and Dynamic Mechanical Analysis was performed on four different SMP formulas to identify appropriate mechanical properties for surgical mesh integration. In vitro testing involved monitoring the time required for a modified surgical mesh to deploy in a 37°C water bath. An acute porcine model was used to test the in vivo unrolling of SMP integrated surgical meshes. The SMP-integrated surgical meshes produced an automated, temperature activated, controlled deployment of surgical mesh on the order of several seconds, via laparoscopy in the animal model. A 30 day chronic rat model was used to test initial in vivo subcutaneous biocompatibility. To produce large more clinical relevant sizes of mesh, a mold was developed to facilitate manufacturing of SMP-integrated surgical mesh. The mold is capable of manufacturing mesh up to 361 cm2, which is believed to accommodate the majority of clinical cases. Results indicate surgical mesh modified with SMP is capable of laparoscopic deployment in vivo, activated by body temperature, and possesses the necessary strength and

  17. Design of Multichannel Osmium-Based Metalloreceptor for Anions and Cations by Taking Profit from Metal-Ligand Interaction and Construction of Molecular Keypad Lock and Memory Device.

    Science.gov (United States)

    Karmakar, Srikanta; Mardanya, Sourav; Pal, Poulami; Baitalik, Sujoy

    2015-12-21

    A polypyridylimidazole-based bifunctional Os(II) complex of the type [(bpy)2Os(tpy-Hbzim-dipy)](ClO4)2 (1), where tpy-Hbzim-dipy = 4'-[4-(4,5-dipyridin-2-yl-1H-imidazol-2-yl)-phenyl]-2,2';6',2″-terpyridine and bpy = 2,2'-bipyridine, has been synthesized and structurally characterized for the construction of multifunctional logic devices. After coordination of an [Os(bpy)2](2+) unit to one of the two bidentate chelating sites, the complex offers a terpyridine motif for binding with cationic guests and an imidazole moiety for interacting with selective anionic species. Consequently, the anion- and cation-binding aspects of the metallorecptor were examined in solution and in the solid state by different spectroscopic and electrochemical methods. The complex behaves as a bifunctional sensor for F(-), AcO(-), CN(-), Fe(2+), and Cu(2+) ions in acetonitrile, whereas it is a highly selective chromogenic chemosensor for only CN(-) and Fe(2+) ions in water. Based on various output signals with a particular set of anionic and cationic inputs, the complex mimics the functions of two-input INHIBIT, OR, NOR, and XNOR logic gates, as well as three-input NOR logic behavior. More importantly, the complicated functions of a keypad lock and memory device were also nicely demonstrated by the complex. Finally, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations also provide a rationale for properly understanding and interpreting the experimentally observed results.

  18. Realization of Minimum and Maximum Gate Function in Ta2O5-based Memristive Devices

    Science.gov (United States)

    Breuer, Thomas; Nielen, Lutz; Roesgen, Bernd; Waser, Rainer; Rana, Vikas; Linn, Eike

    2016-04-01

    Redox-based resistive switching devices (ReRAM) are considered key enablers for future non-volatile memory and logic applications. Functionally enhanced ReRAM devices could enable new hardware concepts, e.g. logic-in-memory or neuromorphic applications. In this work, we demonstrate the implementation of ReRAM-based fuzzy logic gates using Ta2O5 devices to enable analogous Minimum and Maximum operations. The realized gates consist of two anti-serially connected ReRAM cells offering two inputs and one output. The cells offer an endurance up to 106 cycles. By means of exemplary input signals, each gate functionality is verified and signal constraints are highlighted. This realization could improve the efficiency of analogous processing tasks such as sorting networks in the future.

  19. Investigation on the Cyclic Response of Superelastic Shape Memory Alloy (SMA Slit Damper Devices Simulated by Quasi-Static Finite Element (FE Analyses

    Directory of Open Access Journals (Sweden)

    Jong Wan Hu

    2014-02-01

    Full Text Available In this paper, the superelastic shape memory alloy (SMA slit damper system as an alternative design approach for steel structures is intended to be evaluated with respect to inelastic behavior simulated by refined finite element (FE analyses. Although the steel slit dampers conventionally used for aseismic design are able to dissipate a considerable amount of energy generated by the plastic yielding of the base materials, large permanent deformation may occur in the entire structure. After strong seismic events, extra damage repair costs are required to restore the original configuration and to replace defective devices with new ones. Innovative slit dampers fabricated by superelastic SMAs that automatically recover their initial conditions only by the removal of stresses without heat treatment are introduced with a view toward mitigating the problem of permanent deformation. The cyclically tested FE models are calibrated to experimental results for the purpose of predicting accurate behavior. This study also focuses on the material constitutive model that is able to reproduce the inherent behavior of superelastic SMA materials by taking phase transformation between austenite and martensite into consideration. The responses of SMA slit dampers are compared to those of steel slit dampers. Axial stress and strain components are also investigated on the FE models under cyclic loading in an effort to validate the adequacy of FE modeling and then to compare between two slit damper systems. It can be shown that SMA slit dampers exhibit many structural advantages in terms of ultimate strength, moderate energy dissipation and recentering capability.

  20. Volatile Organic Compounds (VOCs)

    Science.gov (United States)

    ... Contact Us Share Volatile Organic Compounds' Impact on Indoor Air Quality On this page: Introduction Sources Health Effects Levels in Homes Steps to Reduce Exposure Standards or Guidelines Additional Resources Introduction Volatile organic compounds ( ...