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Sample records for access memory ram

  1. A realization of the RAM digital filter. [Random Access Memory

    NASA Technical Reports Server (NTRS)

    Zohar, S.

    1976-01-01

    The digital filtering algorithm of W. D. Little, which employs a large RAM to obtain high speed, is implemented in a simple hardware configuration. The nonrecursive version of this filter is compared to the counting digital filter and found to be competitive for low-order filters up to order 7 (8 coefficients).

  2. Remotely Accessible Management System (RAMS).

    ERIC Educational Resources Information Center

    Wood, Rex

    Oakland Schools, an Intermediate School District for Administration, operates a Remotely Accessible Management System (RAMS). RAMS is composed of over 100 computer programs, each of which performs procedures on the files of the 28 local school districts comprising the constituency of Oakland Schools. This regional service agency covers 900 square…

  3. Switching characteristics in Cu:SiO2 by chemical soak methods for resistive random access memory (ReRAM)

    NASA Astrophysics Data System (ADS)

    Chin, Fun-Tat; Lin, Yu-Hsien; Yang, Wen-Luh; Liao, Chin-Hsuan; Lin, Li-Min; Hsiao, Yu-Ping; Chao, Tien-Sheng

    2015-01-01

    A limited copper (Cu)-source Cu:SiO2 switching layer composed of various Cu concentrations was fabricated using a chemical soaking (CS) technique. The switching layer was then studied for developing applications in resistive random access memory (ReRAM) devices. Observing the resistive switching mechanism exhibited by all the samples suggested that Cu conductive filaments formed and ruptured during the set/reset process. The experimental results indicated that the endurance property failure that occurred was related to the joule heating effect. Moreover, the endurance switching cycle increased as the Cu concentration decreased. In high-temperature tests, the samples demonstrated that the operating (set/reset) voltages decreased as the temperature increased, and an Arrhenius plot was used to calculate the activation energy of the set/reset process. In addition, the samples demonstrated stable data retention properties when baked at 85 °C, but the samples with low Cu concentrations exhibited short retention times in the low-resistance state (LRS) during 125 °C tests. Therefore, Cu concentration is a crucial factor in the trade-off between the endurance and retention properties; furthermore, the Cu concentration can be easily modulated using this CS technique.

  4. Ferroelectric random access memories.

    PubMed

    Ishiwara, Hiroshi

    2012-10-01

    Ferroelectric random access memory (FeRAM) is a nonvolatile memory, in which data are stored using hysteretic P-E (polarization vs. electric field) characteristics in a ferroelectric film. In this review, history and characteristics of FeRAMs are first introduced. It is described that there are two types of FeRAMs, capacitor-type and FET-type, and that only the capacitor-type FeRAM is now commercially available. In chapter 2, properties of ferroelectric films are discussed from a viewpoint of FeRAM application, in which particular attention is paid to those of Pb(Zr,Ti)O3, SrBi2Ta2O9, and BiFeO3. Then, cell structures and operation principle of the capacitor-type FeRAMs are discussed in chapter 3. It is described that the stacked technology of ferroelectric capacitors and development of new materials with large remanent polarization are important for fabricating high-density memories. Finally, in chapter 4, the optimized gate structure in ferroelectric-gate field-effect transistors is discussed and experimental results showing excellent data retention characteristics are presented. PMID:23421123

  5. Is random access memory random?

    NASA Technical Reports Server (NTRS)

    Denning, P. J.

    1986-01-01

    Most software is contructed on the assumption that the programs and data are stored in random access memory (RAM). Physical limitations on the relative speeds of processor and memory elements lead to a variety of memory organizations that match processor addressing rate with memory service rate. These include interleaved and cached memory. A very high fraction of a processor's address requests can be satified from the cache without reference to the main memory. The cache requests information from main memory in blocks that can be transferred at the full memory speed. Programmers who organize algorithms for locality can realize the highest performance from these computers.

  6. Garnet Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.

    1995-01-01

    Random-access memory (RAM) devices of proposed type exploit magneto-optical properties of magnetic garnets exhibiting perpendicular anisotropy. Magnetic writing and optical readout used. Provides nonvolatile storage and resists damage by ionizing radiation. Because of basic architecture and pinout requirements, most likely useful as small-capacity memory devices.

  7. SEU evaluation of FeRAM memories for space applications

    NASA Technical Reports Server (NTRS)

    Scheick, L.; Guertin, S.; Nguyen, d.

    2002-01-01

    SEU cross-sections were obtained for two different FeRAM memories: The 64 kbit and 256 kbit Ramtron FeRAM and the Hynix 64 kbit device. The devices were seen to have latch-up characteristics typical of commercial CMOS. Also, errors in the memory were also seen from heavy ion irradiation.

  8. Integrated semiconductor-magnetic random access memory system

    NASA Technical Reports Server (NTRS)

    Katti, Romney R. (Inventor); Blaes, Brent R. (Inventor)

    2001-01-01

    The present disclosure describes a non-volatile magnetic random access memory (RAM) system having a semiconductor control circuit and a magnetic array element. The integrated magnetic RAM system uses CMOS control circuit to read and write data magnetoresistively. The system provides a fast access, non-volatile, radiation hard, high density RAM for high speed computing.

  9. A 16K-bit static IIL RAM with 25-ns access time

    NASA Astrophysics Data System (ADS)

    Inabe, Y.; Hayashi, T.; Kawarada, K.; Miwa, H.; Ogiue, K.

    1982-04-01

    A 16,384 x 1-bit RAM with 25-ns access time, 600-mW power dissipation, and 33 sq mm chip size has been developed. Excellent speed-power performance with high packing density has been achieved by an oxide isolation technology in conjunction with novel ECL circuit techniques and IIL flip-flop memory cells, 980 sq microns (35 x 28 microns) in cell size. Development results have shown that IIL flip-flop memory cell is a trump card for assuring achievement of a high-performance large-capacity bipolar RAM, in the above 16K-bit/chip area.

  10. Computer memory access technique

    NASA Technical Reports Server (NTRS)

    Zottarelli, L. J.

    1967-01-01

    Computer memory access commutator and steering gate configuration produces bipolar current pulses while still employing only the diodes and magnetic cores of the classic commutator, thereby appreciably reducing the complexity of the memory assembly.

  11. Optical RAM row access using WDM-enabled all-passive row/column decoders

    NASA Astrophysics Data System (ADS)

    Papaioannou, Sotirios; Alexoudi, Theoni; Kanellos, George T.; Miliou, Amalia; Pleros, Nikos

    2014-03-01

    Towards achieving a functional RAM organization that reaps the advantages offered by optical technology, a complete set of optical peripheral modules, namely the Row (RD) and Column Decoder (CD) units, is required. In this perspective, we demonstrate an all-passive 2×4 optical RAM RD with row access operation and subsequent all-passive column decoding to control the access of WDM-formatted words in optical RAM rows. The 2×4 RD exploits a WDM-formatted 2-bit-long memory WordLine address along with its complementary value, all of them encoded on four different wavelengths and broadcasted to all RAM rows. The RD relies on an all-passive wavelength-selective filtering matrix (λ-matrix) that ensures a logical `0' output only at the selected RAM row. Subsequently, the RD output of each row drives the respective SOA-MZI-based Row Access Gate (AG) to grant/block the entry of the incoming data words to the whole memory row. In case of a selected row, the data word exits the row AG and enters the respective CD that relies on an allpassive wavelength-selective Arrayed Waveguide Grating (AWG) for decoding the word bits into their individual columns. Both RD and CD procedures are carried out without requiring any active devices, assuming that the memory address and data word bits as well as their inverted values will be available in their optical form by the CPU interface. Proof-of-concept experimental verification exploiting cascaded pairs of AWGs as the λ-matrix is demonstrated at 10Gb/s, providing error-free operation with a peak power penalty lower than 0.2dB for all optical word channels.

  12. Paging memory from random access memory to backing storage in a parallel computer

    DOEpatents

    Archer, Charles J; Blocksome, Michael A; Inglett, Todd A; Ratterman, Joseph D; Smith, Brian E

    2013-05-21

    Paging memory from random access memory (`RAM`) to backing storage in a parallel computer that includes a plurality of compute nodes, including: executing a data processing application on a virtual machine operating system in a virtual machine on a first compute node; providing, by a second compute node, backing storage for the contents of RAM on the first compute node; and swapping, by the virtual machine operating system in the virtual machine on the first compute node, a page of memory from RAM on the first compute node to the backing storage on the second compute node.

  13. Windsock memory COnditioned RAM (CO-RAM) pressure effect: Forced reconnection in the Earth's magnetotail

    NASA Astrophysics Data System (ADS)

    Vörös, Z.; Facskó, G.; Khodachenko, M.; Honkonen, I.; Janhunen, P.; Palmroth, M.

    2014-08-01

    Magnetic reconnection (MR) is a key physical concept explaining the addition of magnetic flux to the magnetotail and closed flux lines back-motion to the dayside magnetosphere. This scenario elaborated by Dungey (1963) can explain many aspects of solar wind-magnetosphere interaction processes, including substorms. However, neither the Dungey model nor its numerous modifications were able to explain fully the onset conditions for MR in the tail. In this paper, we introduce new onset conditions for forced MR in the tail. We call our scenario the "windsock memory conditioned ram pressure effect." Our nonflux transfer-associated forcing is introduced by a combination of the large-scale windsock motions exhibiting memory effects and solar wind dynamic pressure actions on the nightside magnetopause during northward oriented interplanetary magnetic field (IMF). Using global MHD Grand Unified Magnetosphere Ionosphere Coupling Simulation version 4 simulation results, upstream data from Wind, magnetosheath data from Cluster 1 and distant tail data from the two-probe Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun mission, we show that the simultaneous occurrence of vertical windsock motions of the magnetotail and enhanced solar wind dynamic pressure introduces strong nightside disturbances, including enhanced electric fields and persistent vertical cross-tail shear flows. These perturbations, associated with a stream interaction region in the solar wind, drive MR in the tail during episodes of northward oriented interplanetary magnetic field (IMF). We detect MR indirectly, observing plasmoids in the tail and ground-based signatures of earthward moving fast flows. We also consider the application to solar system planets and close-in exoplanets, where the proposed scenario can elucidate some new aspects of solar/stellar wind-magnetosphere interactions.

  14. Dependence of Memory Characteristics on Crystallinity in NiO-ReRAM

    NASA Astrophysics Data System (ADS)

    Dobashi, Kazufumi; Kinosita, Kentaro; Makino, Tatsuya; Okutani, Takumi; Yoda, Takatoshi; Hanada, Akihiro; Kishida, Satoru

    Resistance Random Access Memory (ReRAM) is often made in the sandwiched structure where a transition metal oxide (TMO) film with polycrystalline structure is placed between the upper and the lower electrodes. Although whether resistance switching effect occurs in grains or in the grain boundary is key issue which decides the downsizing limit of memory cells, it has not been clarified yet. We prepared NiO/Pt structure using the DC sputtering method, and investigated the property of resistance change effect in the local area using conducting atomic force microscope. As a result, it was clarified that the resistance change occurred not in the NiO grain but in the NiO grain boundary. Therefore, it was suggested that the limitation of downsizing is decided according to the grain diameter.

  15. 2K nonvolatile shadow RAM and 265K EEPROM SONOS nonvolatile memory development

    SciTech Connect

    Nasby, R.D.; Murray, J.R.; Habermehl, S.D.; Bennett, R.S.; Tafoya-Porras, B.C.; Mahl, P.R.; Rodriguez, J.L.; Jones, R.V.; Knoll, M.G.

    1998-07-01

    This paper describes Silicon Oxide Nitride Oxide Semiconductor (SONOS) nonvolatile memory development at Sandia National Laboratories. A 256K EEPROM nonvolatile memory and a 2K nonvolatile shadow RAM are under development using an n-channel SONOS memory technology. The technology has 1.2 {micro}m minimum features in a twin well design using shallow trench isolation.

  16. Atomic memory access hardware implementations

    SciTech Connect

    Ahn, Jung Ho; Erez, Mattan; Dally, William J

    2015-02-17

    Atomic memory access requests are handled using a variety of systems and methods. According to one example method, a data-processing circuit having an address-request generator that issues requests to a common memory implements a method of processing the requests using a memory-access intervention circuit coupled between the generator and the common memory. The method identifies a current atomic-memory access request from a plurality of memory access requests. A data set is stored that corresponds to the current atomic-memory access request in a data storage circuit within the intervention circuit. It is determined whether the current atomic-memory access request corresponds to at least one previously-stored atomic-memory access request. In response to determining correspondence, the current request is implemented by retrieving data from the common memory. The data is modified in response to the current request and at least one other access request in the memory-access intervention circuit.

  17. Resistive random access memory utilizing ferritin protein with Pt nanoparticles

    NASA Astrophysics Data System (ADS)

    Uenuma, Mutsunori; Kawano, Kentaro; Zheng, Bin; Okamoto, Naofumi; Horita, Masahiro; Yoshii, Shigeo; Yamashita, Ichiro; Uraoka, Yukiharu

    2011-05-01

    This study reports controlled single conductive paths found in resistive random access memory (ReRAM) formed by embedding Pt nanoparticles (Pt NPs) in NiO film. Homogeneous Pt NPs produced and placed by ferritin protein produce electric field convergence which leads to controlled conductive path formation. The ReRAM with Pt NPs shows stable switching behavior. A Pt NP density decrease results in an increase of OFF state resistance and decrease of forming voltage, whereas ON resistance was independent of the Pt NP density, which indicates that a single metal NP in a memory cell will achieve low power and stable operation.

  18. Optical RAM-enabled cache memory and optical routing for chip multiprocessors: technologies and architectures

    NASA Astrophysics Data System (ADS)

    Pleros, Nikos; Maniotis, Pavlos; Alexoudi, Theonitsa; Fitsios, Dimitris; Vagionas, Christos; Papaioannou, Sotiris; Vyrsokinos, K.; Kanellos, George T.

    2014-03-01

    The processor-memory performance gap, commonly referred to as "Memory Wall" problem, owes to the speed mismatch between processor and electronic RAM clock frequencies, forcing current Chip Multiprocessor (CMP) configurations to consume more than 50% of the chip real-estate for caching purposes. In this article, we present our recent work spanning from Si-based integrated optical RAM cell architectures up to complete optical cache memory architectures for Chip Multiprocessor configurations. Moreover, we discuss on e/o router subsystems with up to Tb/s routing capacity for cache interconnection purposes within CMP configurations, currently pursued within the FP7 PhoxTrot project.

  19. Nonvolatile random access memory

    NASA Technical Reports Server (NTRS)

    Wu, Jiin-Chuan (Inventor); Stadler, Henry L. (Inventor); Katti, Romney R. (Inventor)

    1994-01-01

    A nonvolatile magnetic random access memory can be achieved by an array of magnet-Hall effect (M-H) elements. The storage function is realized with a rectangular thin-film ferromagnetic material having an in-plane, uniaxial anisotropy and inplane bipolar remanent magnetization states. The thin-film magnetic element is magnetized by a local applied field, whose direction is used to form either a 0 or 1 state. The element remains in the 0 or 1 state until a switching field is applied to change its state. The stored information is detcted by a Hall-effect sensor which senses the fringing field from the magnetic storage element. The circuit design for addressing each cell includes transistor switches for providing a current of selected polarity to store a binary digit through a separate conductor overlying the magnetic element of the cell. To read out a stored binary digit, transistor switches are employed to provide a current through a row of Hall-effect sensors connected in series and enabling a differential voltage amplifier connected to all Hall-effect sensors of a column in series. To avoid read-out voltage errors due to shunt currents through resistive loads of the Hall-effect sensors of other cells in the same column, at least one transistor switch is provided between every pair of adjacent cells in every row which are not turned on except in the row of the selected cell.

  20. Remote direct memory access

    DOEpatents

    Archer, Charles J.; Blocksome, Michael A.

    2012-12-11

    Methods, parallel computers, and computer program products are disclosed for remote direct memory access. Embodiments include transmitting, from an origin DMA engine on an origin compute node to a plurality target DMA engines on target compute nodes, a request to send message, the request to send message specifying a data to be transferred from the origin DMA engine to data storage on each target compute node; receiving, by each target DMA engine on each target compute node, the request to send message; preparing, by each target DMA engine, to store data according to the data storage reference and the data length, including assigning a base storage address for the data storage reference; sending, by one or more of the target DMA engines, an acknowledgment message acknowledging that all the target DMA engines are prepared to receive a data transmission from the origin DMA engine; receiving, by the origin DMA engine, the acknowledgement message from the one or more of the target DMA engines; and transferring, by the origin DMA engine, data to data storage on each of the target compute nodes according to the data storage reference using a single direct put operation.

  1. Subthreshold-swing-adjustable tunneling-field-effect-transistor-based random-access memory for nonvolatile operation

    NASA Astrophysics Data System (ADS)

    Huh, In; Cheon, Woo Young; Choi, Woo Young

    2016-04-01

    A subthreshold-swing-adjustable tunneling-field-effect-transistor-based random-access memory (SAT RAM) has been proposed and fabricated for low-power nonvolatile memory applications. The proposed SAT RAM cell demonstrates adjustable subthreshold swing (SS) depending on stored information: small SS in the erase state ("1" state) and large SS in the program state ("0" state). Thus, SAT RAM cells can achieve low read voltage (Vread) with a large memory window in addition to the effective suppression of ambipolar behavior. These unique features of the SAT RAM are originated from the locally stored charge, which modulates the tunneling barrier width (Wtun) of the source-to-channel tunneling junction.

  2. Plated wire random access memories

    NASA Technical Reports Server (NTRS)

    Gouldin, L. D.

    1975-01-01

    A program was conducted to construct 4096-work by 18-bit random access, NDRO-plated wire memory units. The memory units were subjected to comprehensive functional and environmental tests at the end-item level to verify comformance with the specified requirements. A technical description of the unit is given, along with acceptance test data sheets.

  3. Memory availability and referential access

    PubMed Central

    Johns, Clinton L.; Gordon, Peter C.; Long, Debra L.; Swaab, Tamara Y.

    2013-01-01

    Most theories of coreference specify linguistic factors that modulate antecedent accessibility in memory; however, whether non-linguistic factors also affect coreferential access is unknown. Here we examined the impact of a non-linguistic generation task (letter transposition) on the repeated-name penalty, a processing difficulty observed when coreferential repeated names refer to syntactically prominent (and thus more accessible) antecedents. In Experiment 1, generation improved online (event-related potentials) and offline (recognition memory) accessibility of names in word lists. In Experiment 2, we manipulated generation and syntactic prominence of antecedent names in sentences; both improved online and offline accessibility, but only syntactic prominence elicited a repeated-name penalty. Our results have three important implications: first, the form of a referential expression interacts with an antecedent’s status in the discourse model during coreference; second, availability in memory and referential accessibility are separable; and finally, theories of coreference must better integrate known properties of the human memory system. PMID:24443621

  4. Energy-Saving RAM-Power Tap

    NASA Technical Reports Server (NTRS)

    Bruner, Alan Roy

    1987-01-01

    Reverse-flow HEXFET(R) minimizes voltage drop and power dissipation. HEXFET(R) scheme reduces voltage drop by approximately 80 percent. Design for power tap for random-access memory (RAM) has potential application in digital systems.

  5. Experimental developments of A2RAM memory cells on SOI and bulk substrates

    NASA Astrophysics Data System (ADS)

    Rodriguez, Noel; Gamiz, Francisco; Navarro, Carlos; Marquez, Carlos; Andrieu, François; Faynot, Olivier; Cristoloveanu, Sorin

    2015-01-01

    A2RAM prototype devices have been demonstrated in both SOI and bulk technologies. The fabrication process has successfully achieved the characteristic retrograde doping profile of the channel which allows the coexistence of electrons and holes in the same body while maintaining low-voltage single-gate operation. The different prototypes have been electrically characterized, all of them exhibiting memory effect. The SOI samples present the best performance, showing very attractive current margin between states, competitive retention time, reasonable variability, immunity to disturbance events and no endurance issues even in the short-channel devices fabricated in the most advanced 22 nm process.

  6. Multilevel Cell Storage and Resistance Variability in Resistive Random Access Memory

    NASA Astrophysics Data System (ADS)

    Pantelis, D. I.; Karakizis, P. N.; Dragatogiannis, D. A.; Charitidis, C. A.

    2016-06-01

    Multilevel per cell (MLC) storage in resistive random access memory (ReRAM) is attractive in achieving high-density and low-cost memory and will be required in future. In this chapter, MLC storage and resistance variability and reliability of multilevel in ReRAM are discussed. Different MLC operation schemes with their physical mechanisms and a comprehensive analysis of resistance variability have been provided. Various factors that can induce variability and their effect on the resistance margin between the multiple resistance levels are assessed. The reliability characteristics and the impact on MLC storage have also been assessed.

  7. Dynamic computing random access memory

    NASA Astrophysics Data System (ADS)

    Traversa, F. L.; Bonani, F.; Pershin, Y. V.; Di Ventra, M.

    2014-07-01

    The present von Neumann computing paradigm involves a significant amount of information transfer between a central processing unit and memory, with concomitant limitations in the actual execution speed. However, it has been recently argued that a different form of computation, dubbed memcomputing (Di Ventra and Pershin 2013 Nat. Phys. 9 200-2) and inspired by the operation of our brain, can resolve the intrinsic limitations of present day architectures by allowing for computing and storing of information on the same physical platform. Here we show a simple and practical realization of memcomputing that utilizes easy-to-build memcapacitive systems. We name this architecture dynamic computing random access memory (DCRAM). We show that DCRAM provides massively-parallel and polymorphic digital logic, namely it allows for different logic operations with the same architecture, by varying only the control signals. In addition, by taking into account realistic parameters, its energy expenditures can be as low as a few fJ per operation. DCRAM is fully compatible with CMOS technology, can be realized with current fabrication facilities, and therefore can really serve as an alternative to the present computing technology.

  8. Dynamic computing random access memory.

    PubMed

    Traversa, F L; Bonani, F; Pershin, Y V; Di Ventra, M

    2014-07-18

    The present von Neumann computing paradigm involves a significant amount of information transfer between a central processing unit and memory, with concomitant limitations in the actual execution speed. However, it has been recently argued that a different form of computation, dubbed memcomputing (Di Ventra and Pershin 2013 Nat. Phys. 9 200-2) and inspired by the operation of our brain, can resolve the intrinsic limitations of present day architectures by allowing for computing and storing of information on the same physical platform. Here we show a simple and practical realization of memcomputing that utilizes easy-to-build memcapacitive systems. We name this architecture dynamic computing random access memory (DCRAM). We show that DCRAM provides massively-parallel and polymorphic digital logic, namely it allows for different logic operations with the same architecture, by varying only the control signals. In addition, by taking into account realistic parameters, its energy expenditures can be as low as a few fJ per operation. DCRAM is fully compatible with CMOS technology, can be realized with current fabrication facilities, and therefore can really serve as an alternative to the present computing technology. PMID:24972387

  9. Memory access in shared virtual memory

    SciTech Connect

    Berrendorf, R. )

    1992-01-01

    Shared virtual memory (SVM) is a virtual memory layer with a single address space on top of a distributed real memory on parallel computers. We examine the behavior and performance of SVM running a parallel program with medium-grained, loop-level parallelism on top of it. A simulator for the underlying parallel architecture can be used to examine the behavior of SVM more deeply. The influence of several parameters, such as the number of processors, page size, cold or warm start, and restricted page replication, is studied.

  10. Memory access in shared virtual memory

    SciTech Connect

    Berrendorf, R.

    1992-09-01

    Shared virtual memory (SVM) is a virtual memory layer with a single address space on top of a distributed real memory on parallel computers. We examine the behavior and performance of SVM running a parallel program with medium-grained, loop-level parallelism on top of it. A simulator for the underlying parallel architecture can be used to examine the behavior of SVM more deeply. The influence of several parameters, such as the number of processors, page size, cold or warm start, and restricted page replication, is studied.

  11. Conductive Filament Expansion in TaOx Bipolar Resistive Random Access Memory during Pulse Cycling

    NASA Astrophysics Data System (ADS)

    Ninomiya, Takeki; Katayama, Koji; Muraoka, Shunsaku; Yasuhara, Ryutaro; Mikawa, Takumi; Wei, Zhiqiang

    2013-11-01

    The post-cycling data retention of filamentary operated resistive random access memory (ReRAM) can be improved by minimizing conductive filament expansion during pulse cycling. We find that filament size gradually grows with increasing pulse cycles due to oxygen diffusion from the region surrounding each filament. To achieve long term use of ReRAM while suppressing filament expansion, the key is to control both electric power and pulse width input during switching. We minimize CF expansion based on this concept and demonstrate long data retention even after 106 pulse switchings under optimized reset conditions.

  12. Analysis and modeling of resistive switching mechanisms oriented to resistive random-access memory

    NASA Astrophysics Data System (ADS)

    Huang, Da; Wu, Jun-Jie; Tang, Yu-Hua

    2013-03-01

    With the progress of the semiconductor industry, the resistive random-access memory (RAM) has drawn increasing attention. The discovery of the memristor has brought much attention to this study. Research has focused on the resistive switching characteristics of different materials and the analysis of resistive switching mechanisms. We discuss the resistive switching mechanisms of different materials in this paper and analyze the differences of those mechanisms from the view point of circuitry to establish their respective circuit models. Finally, simulations are presented. We give the prospect of using different materials in resistive RAM on account of their resistive switching mechanisms, which are applied to explain their resistive switchings.

  13. Magnetic Analog Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.; Wu, Jiin-Chuan; Stadler, Henry L.

    1991-01-01

    Proposed integrated, solid-state, analog random-access memory base on principle of magnetic writing and magnetoresistive reading. Current in writing conductor magnetizes storage layer. Remanent magnetization in storage layer penetrates readout layer and detected by magnetoresistive effect or Hall effect. Memory cells are part of integrated circuit including associated reading and writing transistors. Intended to provide high storage density and rapid access, nonvolatile, consumes little power, and relatively invulnerable to ionizing radiation.

  14. Joule heating effect in nonpolar and bipolar resistive random access memory

    NASA Astrophysics Data System (ADS)

    Uenuma, Mutsunori; Ishikawa, Yasuaki; Uraoka, Yukiharu

    2015-08-01

    The position of the conductive filament (CF) and the heating behaviour during a switching process in nonpolar and bipolar resistive random access memories (ReRAMs) were evaluated using thermal analysis. The position of the CF was clearly observed from Joule heating at the surface of the electrode on the CF. The position of the CF did not change during the switching cycle, except in the case of an unstable CF. In the nonpolar ReRAM, spike-shaped temperature increments were observed during both the forming and the set processes because of the overshoot current. However, the behaviour of the temperature increment in the bipolar ReRAM was virtually consistent with the profile of the electrical power.

  15. Voltage induced magnetostrictive switching of nanomagnets: Strain assisted strain transfer torque random access memory

    NASA Astrophysics Data System (ADS)

    Khan, Asif; Nikonov, Dmitri E.; Manipatruni, Sasikanth; Ghani, Tahir; Young, Ian A.

    2014-06-01

    A spintronic device, called the "strain assisted spin transfer torque (STT) random access memory (RAM)," is proposed by combining the magnetostriction effect and the spin transfer torque effect which can result in a dramatic improvement in the energy dissipation relative to a conventional STT-RAM. Magnetization switching in the device which is a piezoelectric-ferromagnetic heterostructure via the combined magnetostriction and STT effect is simulated by solving the Landau-Lifshitz-Gilbert equation incorporating the influence of thermal noise. The simulations show that, in such a device, each of these two mechanisms (magnetostriction and spin transfer torque) provides in a 90° rotation of the magnetization leading a deterministic 180° switching with a critical current significantly smaller than that required for spin torque alone. Such a scheme is an attractive option for writing magnetic RAM cells.

  16. Microstructural transitions in resistive random access memory composed of molybdenum oxide with copper during switching cycles.

    PubMed

    Arita, Masashi; Ohno, Yuuki; Murakami, Yosuke; Takamizawa, Keisuke; Tsurumaki-Fukuchi, Atsushi; Takahashi, Yasuo

    2016-08-21

    The switching operation of a Cu/MoOx/TiN resistive random access memory (ReRAM) device was investigated using in situ transmission electron microscopy (TEM), where the TiN surface was slightly oxidized (ox-TiN). The relationship between the switching properties and the dynamics of the ReRAM microstructure was confirmed experimentally. The growth and/or shrinkage of the conductive filament (CF) can be classified into two set modes and two reset modes. These switching modes depend on the device's switching history, factors such as the amount of Cu inclusions in the MoOx layer and the CF geometry. High currents are needed to produce an observable change in the CF. However, sharp and stable switching behaviour can be achieved without requiring such a major change. The local region around the CF is thought to contribute to the ReRAM switching process. PMID:27456192

  17. Improvement of Resistive Random Access Memory Device Performance via Embedding of Low-K Dielectric Layer.

    PubMed

    Jang, Sung Hwan; Ryu, Ju Tae; Jung, Hyun Soo; Kim, Tae Whan

    2016-02-01

    The switching mechanisms of resistive random access memories (ReRAMs) were strongly related to the formation and rupture of conduction filaments (CFs) in the transition metal oxide (TMO) layer. The novel method approached to enhance the electrical characteristics of ReRAMs by introducing of the local insertion of the low-k dielectric layer inside the TMO layer. Simulation results showed that the insertion of the low-k dielectric layer in the TMO layer reduced the switching volume and the generation of CFs. The large variation of resistive switching properties was caused by the stochastic characteristics of the CFs, which was involved in switching by generation and rupture. The electrical characteristics of the novel ReRAMs exhibited a low reset current of below 20 microA, the high uniformity of the resistive switching, and the narrow variation of the resistance for the high resistance state. PMID:27433626

  18. Voltage induced magnetostrictive switching of nanomagnets: Strain assisted strain transfer torque random access memory

    SciTech Connect

    Khan, Asif Nikonov, Dmitri E.; Manipatruni, Sasikanth; Ghani, Tahir; Young, Ian A.

    2014-06-30

    A spintronic device, called the “strain assisted spin transfer torque (STT) random access memory (RAM),” is proposed by combining the magnetostriction effect and the spin transfer torque effect which can result in a dramatic improvement in the energy dissipation relative to a conventional STT-RAM. Magnetization switching in the device which is a piezoelectric-ferromagnetic heterostructure via the combined magnetostriction and STT effect is simulated by solving the Landau-Lifshitz-Gilbert equation incorporating the influence of thermal noise. The simulations show that, in such a device, each of these two mechanisms (magnetostriction and spin transfer torque) provides in a 90° rotation of the magnetization leading a deterministic 180° switching with a critical current significantly smaller than that required for spin torque alone. Such a scheme is an attractive option for writing magnetic RAM cells.

  19. Experimental Results and Issues on Equalization for Nonlinear Memory Channel: Pre-Cursor Enhanced Ram-DFE Canceler

    NASA Technical Reports Server (NTRS)

    Yuan, Lu; LeBlanc, James

    1998-01-01

    This thesis investigates the effects of the High Power Amplifier (HPA) and the filters over a satellite or telemetry channel. The Volterra series expression is presented for the nonlinear channel with memory, and the algorithm is based on the finite-state machine model. A RAM-based algorithm operating on the receiver side, Pre-cursor Enhanced RAM-FSE Canceler (PERC) is developed. A high order modulation scheme , 16-QAM is used for simulation, the results show that PERC provides an efficient and reliable method to transmit data on the bandlimited nonlinear channel. The contribution of PERC algorithm is that it includes both pre-cursors and post-cursors as the RAM address lines, and suggests a new way to make decision on the pre-addresses. Compared with the RAM-DFE structure that only includes post- addresses, the BER versus Eb/NO performance of PERC is substantially enhanced. Experiments are performed for PERC algorithms with different parameters on AWGN channels, and the results are compared and analyzed. The investigation of this thesis includes software simulation and hardware verification. Hardware is setup to collect actual TWT data. Simulation on both the software-generated data and the real-world data are performed. Practical limitations are considered for the hardware collected data. Simulation results verified the reliability of the PERC algorithm. This work was conducted at NMSU in the Center for Space Telemetering and Telecommunications Systems in the Klipsch School of Electrical and Computer Engineering Department.

  20. Microstructural transitions in resistive random access memory composed of molybdenum oxide with copper during switching cycles

    NASA Astrophysics Data System (ADS)

    Arita, Masashi; Ohno, Yuuki; Murakami, Yosuke; Takamizawa, Keisuke; Tsurumaki-Fukuchi, Atsushi; Takahashi, Yasuo

    2016-08-01

    The switching operation of a Cu/MoOx/TiN resistive random access memory (ReRAM) device was investigated using in situ transmission electron microscopy (TEM), where the TiN surface was slightly oxidized (ox-TiN). The relationship between the switching properties and the dynamics of the ReRAM microstructure was confirmed experimentally. The growth and/or shrinkage of the conductive filament (CF) can be classified into two set modes and two reset modes. These switching modes depend on the device's switching history, factors such as the amount of Cu inclusions in the MoOx layer and the CF geometry. High currents are needed to produce an observable change in the CF. However, sharp and stable switching behaviour can be achieved without requiring such a major change. The local region around the CF is thought to contribute to the ReRAM switching process.The switching operation of a Cu/MoOx/TiN resistive random access memory (ReRAM) device was investigated using in situ transmission electron microscopy (TEM), where the TiN surface was slightly oxidized (ox-TiN). The relationship between the switching properties and the dynamics of the ReRAM microstructure was confirmed experimentally. The growth and/or shrinkage of the conductive filament (CF) can be classified into two set modes and two reset modes. These switching modes depend on the device's switching history, factors such as the amount of Cu inclusions in the MoOx layer and the CF geometry. High currents are needed to produce an observable change in the CF. However, sharp and stable switching behaviour can be achieved without requiring such a major change. The local region around the CF is thought to contribute to the ReRAM switching process. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02602h

  1. Low latency memory access and synchronization

    DOEpatents

    Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Hoenicke, Dirk; Ohmacht, Martin; Steinmacher-Burow, Burkhard D.; Takken, Todd E.; Vranas, Pavlos M.

    2007-02-06

    A low latency memory system access is provided in association with a weakly-ordered multiprocessor system. Each processor in the multiprocessor shares resources, and each shared resource has an associated lock within a locking device that provides support for synchronization between the multiple processors in the multiprocessor and the orderly sharing of the resources. A processor only has permission to access a resource when it owns the lock associated with that resource, and an attempt by a processor to own a lock requires only a single load operation, rather than a traditional atomic load followed by store, such that the processor only performs a read operation and the hardware locking device performs a subsequent write operation rather than the processor. A simple prefetching for non-contiguous data structures is also disclosed. A memory line is redefined so that in addition to the normal physical memory data, every line includes a pointer that is large enough to point to any other line in the memory, wherein the pointers to determine which memory line to prefetch rather than some other predictive algorithm. This enables hardware to effectively prefetch memory access patterns that are non-contiguous, but repetitive.

  2. Low latency memory access and synchronization

    DOEpatents

    Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Hoenicke, Dirk; Ohmacht, Martin; Steinmacher-Burow, Burkhard D.; Takken, Todd E. , Vranas; Pavlos M.

    2010-10-19

    A low latency memory system access is provided in association with a weakly-ordered multiprocessor system. Bach processor in the multiprocessor shares resources, and each shared resource has an associated lock within a locking device that provides support for synchronization between the multiple processors in the multiprocessor and the orderly sharing of the resources. A processor only has permission to access a resource when it owns the lock associated with that resource, and an attempt by a processor to own a lock requires only a single load operation, rather than a traditional atomic load followed by store, such that the processor only performs a read operation and the hardware locking device performs a subsequent write operation rather than the processor. A simple prefetching for non-contiguous data structures is also disclosed. A memory line is redefined so that in addition to the normal physical memory data, every line includes a pointer that is large enough to point to any other line in the memory, wherein the pointers to determine which memory line to prefetch rather than some other predictive algorithm. This enables hardware to effectively prefetch memory access patterns that are non-contiguous, but repetitive.

  3. Flexible conductive-bridging random-access-memory cell vertically stacked with top Ag electrode, PEO, PVK, and bottom Pt electrode.

    PubMed

    Seung, Hyun-Min; Kwon, Kyoung-Cheol; Lee, Gon-Sub; Park, Jea-Gun

    2014-10-31

    Flexible conductive-bridging random-access-memory (RAM) cells were fabricated with a cross-bar memory cell stacked with a top Ag electrode, conductive polymer (poly(n-vinylcarbazole): PVK), electrolyte (polyethylene oxide: PEO), bottom Pt electrode, and flexible substrate (polyethersulfone: PES), exhibiting the bipolar switching behavior of resistive random access memory (ReRAM). The cell also exhibited bending-fatigue-free nonvolatile memory characteristics: i.e., a set voltage of 1.0 V, a reset voltage of -1.6 V, retention time of >1 × 10(5) s with a memory margin of 9.2 × 10(5), program/erase endurance cycles of >10(2) with a memory margin of 8.4 × 10(5), and bending-fatigue-free cycles of ∼1 × 10(3) with a memory margin (I(on)/I(off)) of 3.3 × 10(5). PMID:25297517

  4. Extremely small test cell structure for resistive random access memory element with removable bottom electrode

    SciTech Connect

    Koh, Sang-Gyu; Kishida, Satoru; Kinoshita, Kentaro

    2014-02-24

    We established a method of preparing an extremely small memory cell by fabricating a resistive random access memory (ReRAM) structure on the tip of a cantilever of an atomic force microscope. This structure has the high robustness against the drift of the cantilever, and the effective cell size was estimated to be less than 10 nm in diameter due to the electric field concentration at the tip of the cantilever, which was confirmed using electric field simulation. The proposed structure, which has a removable bottom electrode, enables not only the preparation of a tiny ReRAM structure but also the performance of unique experiments, by making the most of its high robustness against the drift of the cantilever.

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

    SciTech Connect

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

    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.

  6. The effect of ultraviolet irradiation on data retention characteristics of resistive random access memory

    NASA Astrophysics Data System (ADS)

    Kinoshita, Kentaro; Kimura, Kouhei; Ohmi, Koutoku; Kishida, Satoru

    It is getting more and more serious to generate soft-errors by cosmic radiation, with increasing the density of memory devices. Therefore, the irradiation resistance of resistance random access memory (ReRAM) to cosmic radiation has to be elucidated for practical use. In this paper, we investigated the data retention characteristics against ultraviolet irradiation to ReRAM with Pt/NiO/ITO structure. Soft-errors were confirmed to be caused by ultraviolet irradiation in both low and high resistance states. The analysis of irradiation frequency dependence of data retention characteristics suggested that electronic excitation by the irradiation caused the errors. Based on a statistically estimated soft-error rate, the errors were suggested to be caused by aggregation and dispersion of oxygen vacancies due to the generation of electron-hole pairs and valence change by the ultraviolet irradiation.

  7. Gate controllable resistive random access memory devices using reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Hazra, Preetam; Resmi, A. N.; Jinesh, K. B.

    2016-04-01

    The biggest challenge in the resistive random access memory (ReRAM) technology is that the basic operational parameters, such as the set and reset voltages, the current on-off ratios (hence the power), and their operational speeds, strongly depend on the active and electrode materials and their processing methods. Therefore, for its actual technological implementations, the unification of the operational parameters of the ReRAM devices appears to be a difficult task. In this letter, we show that by fabricating a resistive memory device in a thin film transistor configuration and thus applying an external gate bias, we can control the switching voltage very accurately. Taking partially reduced graphene oxide, the gate controllable switching is demonstrated, and the possible mechanisms are discussed.

  8. Non-volatile magnetic random access memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R. (Inventor); Stadler, Henry L. (Inventor); Wu, Jiin-Chuan (Inventor)

    1994-01-01

    Improvements are made in a non-volatile magnetic random access memory. Such a memory is comprised of an array of unit cells, each having a Hall-effect sensor and a thin-film magnetic element made of material having an in-plane, uniaxial anisotropy and in-plane, bipolar remanent magnetization states. The Hall-effect sensor is made more sensitive by using a 1 m thick molecular beam epitaxy grown InAs layer on a silicon substrate by employing a GaAs/AlGaAs/InAlAs superlattice buffering layer. One improvement avoids current shunting problems of matrix architecture. Another improvement reduces the required magnetizing current for the micromagnets. Another improvement relates to the use of GaAs technology wherein high electron-mobility GaAs MESFETs provide faster switching times. Still another improvement relates to a method for configuring the invention as a three-dimensional random access memory.

  9. New Approach on Logic Application of Ferroelectric Random Access Memory Technology

    NASA Astrophysics Data System (ADS)

    Takayama, Masao; Koyama, Shinzo; Nozawa, Hiroshi

    2002-11-01

    In this paper, a new approach is described to solve some problems that occur when ferroelectric random access memory (FeRAM) is applied to logic circuits, particularly RSA cryptography. Application of a programmable switch device to RSA-based cryptography processing circuits was explored. RSA-based cryptography processing circuits have been designed as code conversion circuits. The capacity of the code conversion programmable AND gate and FeRAM and the translation rate have been investigated as a function of bit length. As a result, a problem of huge capacity at the practical bit length can be predicted theoretically. To solve this problem, we propose a new scheme for circuits and a new algorithm of logic operation using the binomial theorem.

  10. An amorphous titanium dioxide metal insulator metal selector device for resistive random access memory crossbar arrays with tunable voltage margin

    NASA Astrophysics Data System (ADS)

    Cortese, Simone; Khiat, Ali; Carta, Daniela; Light, Mark E.; Prodromakis, Themistoklis

    2016-01-01

    Resistive random access memory (ReRAM) crossbar arrays have become one of the most promising candidates for next-generation non volatile memories. To become a mature technology, the sneak path current issue must be solved without compromising all the advantages that crossbars offer in terms of electrical performances and fabrication complexity. Here, we present a highly integrable access device based on nickel and sub-stoichiometric amorphous titanium dioxide (TiO2-x), in a metal insulator metal crossbar structure. The high voltage margin of 3 V, amongst the highest reported for monolayer selector devices, and the good current density of 104 A/cm2 make it suitable to sustain ReRAM read and write operations, effectively tackling sneak currents in crossbars without compromising fabrication complexity in a 1 Selector 1 Resistor (1S1R) architecture. Furthermore, the voltage margin is found to be tunable by an annealing step without affecting the device's characteristics.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Remote direct memory access over datagrams

    DOEpatents

    Grant, Ryan Eric; Rashti, Mohammad Javad; Balaji, Pavan; Afsahi, Ahmad

    2014-12-02

    A communication stack for providing remote direct memory access (RDMA) over a datagram network is disclosed. The communication stack has a user level interface configured to accept datagram related input and communicate with an RDMA enabled network interface card (NIC) via an NIC driver. The communication stack also has an RDMA protocol layer configured to supply one or more data transfer primitives for the datagram related input of the user level. The communication stack further has a direct data placement (DDP) layer configured to transfer the datagram related input from a user storage to a transport layer based on the one or more data transfer primitives by way of a lower layer protocol (LLP) over the datagram network.

  13. Parallel Optical Random Access Memory (PORAM)

    NASA Technical Reports Server (NTRS)

    Alphonse, G. A.

    1989-01-01

    It is shown that the need to minimize component count, power and size, and to maximize packing density require a parallel optical random access memory to be designed in a two-level hierarchy: a modular level and an interconnect level. Three module designs are proposed, in the order of research and development requirements. The first uses state-of-the-art components, including individually addressed laser diode arrays, acousto-optic (AO) deflectors and magneto-optic (MO) storage medium, aimed at moderate size, moderate power, and high packing density. The next design level uses an electron-trapping (ET) medium to reduce optical power requirements. The third design uses a beam-steering grating surface emitter (GSE) array to reduce size further and minimize the number of components.

  14. Direct memory access transfer completion notification

    DOEpatents

    Chen, Dong; Giampapa, Mark E.; Heidelberger, Philip; Kumar, Sameer; Parker, Jeffrey J.; Steinmacher-Burow, Burkhard D.; Vranas, Pavlos

    2010-07-27

    Methods, compute nodes, and computer program products are provided for direct memory access (`DMA`) transfer completion notification. Embodiments include determining, by an origin DMA engine on an origin compute node, whether a data descriptor for an application message to be sent to a target compute node is currently in an injection first-in-first-out (`FIFO`) buffer in dependence upon a sequence number previously associated with the data descriptor, the total number of descriptors currently in the injection FIFO buffer, and the current sequence number for the newest data descriptor stored in the injection FIFO buffer; and notifying a processor core on the origin DMA engine that the message has been sent if the data descriptor for the message is not currently in the injection FIFO buffer.

  15. Oxide Defect Engineering Methods for Valence Change (VCM) Resistive Random Access Memories

    NASA Astrophysics Data System (ADS)

    Capulong, Jihan O.

    Electrical switching requirements for resistive random access memory (ReRAM) devices are multifaceted, based on device application. Thus, it is important to obtain an understanding of these switching properties and how they relate to the oxygen vacancy concentration and oxygen vacancy defects. Oxygen vacancy defects in the switching oxide of valence-change-based ReRAM (VCM ReRAM) play a significant role in device switching properties. Oxygen vacancies facilitate resistive switching as they form the conductive filament that changes the resistance state of the device. This dissertation will present two methods of modulating the defect concentration in VCM ReRAM composed of Pt/HfOx/Ti stack: 1) rapid thermal annealing (RTA) in Ar using different temperatures, and 2) doping using ion implantation under different dose levels. Metrology techniques such as x-ray diffractometry (XRD), x-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy were utilized to characterize the HfOx switching oxide, which provided insight on the material properties and oxygen vacancy concentration in the oxide that was used to explain the changes in the electrical properties of the ReRAM devices. The resulting impact on the resistive switching characteristics of the devices, such as the forming voltage, set and reset threshold voltages, ON and OFF resistances, resistance ratio, and switching dispersion or uniformity were explored and summarized. Annealing in Ar showed significant impact on the forming voltage, with as much as 45% (from 22V to 12 V) of improvement, as the annealing temperature was increased. However, drawbacks of a higher oxide leakage and worse switching uniformity were seen with increasing annealing temperature. Meanwhile, doping the oxide by ion implantation showed significant effects on the resistive switching characteristics. Ta doping modulated the following switching properties with increasing dose: a) the reduction of the forming voltage, and Vset

  16. Conductance Quantization in Resistive Random Access Memory.

    PubMed

    Li, Yang; Long, Shibing; Liu, Yang; Hu, Chen; Teng, Jiao; Liu, Qi; Lv, Hangbing; Suñé, Jordi; Liu, Ming

    2015-12-01

    The intrinsic scaling-down ability, simple metal-insulator-metal (MIM) sandwich structure, excellent performances, and complementary metal-oxide-semiconductor (CMOS) technology-compatible fabrication processes make resistive random access memory (RRAM) one of the most promising candidates for the next-generation memory. The RRAM device also exhibits rich electrical, thermal, magnetic, and optical effects, in close correlation with the abundant resistive switching (RS) materials, metal-oxide interface, and multiple RS mechanisms including the formation/rupture of nanoscale to atomic-sized conductive filament (CF) incorporated in RS layer. Conductance quantization effect has been observed in the atomic-sized CF in RRAM, which provides a good opportunity to deeply investigate the RS mechanism in mesoscopic dimension. In this review paper, the operating principles of RRAM are introduced first, followed by the summarization of the basic conductance quantization phenomenon in RRAM and the related RS mechanisms, device structures, and material system. Then, we discuss the theory and modeling of quantum transport in RRAM. Finally, we present the opportunities and challenges in quantized RRAM devices and our views on the future prospects. PMID:26501832

  17. Conductance Quantization in Resistive Random Access Memory

    NASA Astrophysics Data System (ADS)

    Li, Yang; Long, Shibing; Liu, Yang; Hu, Chen; Teng, Jiao; Liu, Qi; Lv, Hangbing; Suñé, Jordi; Liu, Ming

    2015-10-01

    The intrinsic scaling-down ability, simple metal-insulator-metal (MIM) sandwich structure, excellent performances, and complementary metal-oxide-semiconductor (CMOS) technology-compatible fabrication processes make resistive random access memory (RRAM) one of the most promising candidates for the next-generation memory. The RRAM device also exhibits rich electrical, thermal, magnetic, and optical effects, in close correlation with the abundant resistive switching (RS) materials, metal-oxide interface, and multiple RS mechanisms including the formation/rupture of nanoscale to atomic-sized conductive filament (CF) incorporated in RS layer. Conductance quantization effect has been observed in the atomic-sized CF in RRAM, which provides a good opportunity to deeply investigate the RS mechanism in mesoscopic dimension. In this review paper, the operating principles of RRAM are introduced first, followed by the summarization of the basic conductance quantization phenomenon in RRAM and the related RS mechanisms, device structures, and material system. Then, we discuss the theory and modeling of quantum transport in RRAM. Finally, we present the opportunities and challenges in quantized RRAM devices and our views on the future prospects.

  18. Scaling constraints in nanoelectronic random-access memories.

    PubMed

    Amsinck, Christian J; Di Spigna, Neil H; Nackashi, David P; Franzon, Paul D

    2005-10-01

    Nanoelectronic molecular and magnetic tunnel junction (MTJ) MRAM crossbar memory systems have the potential to present significant area advantages (4 to 6F(2)) compared to CMOS-based systems. The scalability of these conductivity-switched RAM arrays is examined by establishing criteria for correct functionality based on the readout margin. Using a combined circuit theoretical modelling and simulation approach, the impact of both the device and interconnect architecture on the scalability of a conductivity-state memory system is quantified. This establishes criteria showing the conditions and on/off ratios for the large-scale integration of molecular devices, guiding molecular device design. With 10% readout margin on the resistive load, a memory device needs to have an on/off ratio of at least 7 to be integrated into a 64 x 64 array, while an on/off ratio of 43 is necessary to scale the memory to 512 x 512. PMID:20818005

  19. Integration of SrBi2Ta2O9 thin films for high density ferroelectric random access memory

    NASA Astrophysics Data System (ADS)

    Wouters, D. J.; Maes, D.; Goux, L.; Lisoni, J. G.; Paraschiv, V.; Johnson, J. A.; Schwitters, M.; Everaert, J.-L.; Boullart, W.; Schaekers, M.; Willegems, M.; Vander Meeren, H.; Haspeslagh, L.; Artoni, C.; Caputa, C.; Casella, P.; Corallo, G.; Russo, G.; Zambrano, R.; Monchoix, H.; Vecchio, G.; Van Autryve, L.

    2006-09-01

    Ferroelectric random access memory (FeRAM) is an attractive candidate technology for embedded nonvolatile memory, especially in applications where low power and high program speed are important. Market introduction of high-density FeRAM is, however, lagging behind standard complementary metal-oxide semiconductor (CMOS) because of the difficult integration technology. This paper discusses the major integration issues for high-density FeRAM, based on SrBi2Ta2O9 (strontium bismuth tantalate or SBT), in relation to the fabrication of our stacked cell structure. We have worked in the previous years on the development of SBT-FeRAM integration technology, based on a so-called pseudo-three-dimensional (3D) cell, with a capacitor that can be scaled from quasi two-dimensional towards a true three-dimensional capacitor where the sidewalls will importantly contribute to the signal. In the first phase of our integration development, we integrated our FeRAM cell in a 0.35μm CMOS technology. In a second phase, then, possibility of scaling of our cell is demonstrated in 0.18μm technology. The excellent electrical and reliability properties of the small integrated ferroelectric capacitors prove the feasibility of the technology, while the verification of the potential 3D effect confirms the basic scaling potential of our concept beyond that of the single-mask capacitor. The paper outlines the different material and technological challenges, and working solutions are demonstrated. While some issues are specific to our own cell, many are applicable to different stacked FeRAM cell concepts, or will become more general concerns when more developments are moving into 3D structures.

  20. 76 FR 55417 - In the Matter of Certain Dynamic Random Access Memory and Nand Flash Memory Devices and Products...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-07

    ... COMMISSION In the Matter of Certain Dynamic Random Access Memory and Nand Flash Memory Devices and Products... States after importation of certain dynamic random access memory and NAND flash memory devices and... the sale within the United States after importation of certain dynamic random access memory and...

  1. Experimental evidence of the quantum point contact theory in the conduction mechanism of bipolar HfO2-based resistive random access memories

    NASA Astrophysics Data System (ADS)

    Prócel, L. M.; Trojman, L.; Moreno, J.; Crupi, F.; Maccaronio, V.; Degraeve, R.; Goux, L.; Simoen, E.

    2013-08-01

    The quantum point contact (QPC) model for dielectric breakdown is used to explain the electron transport mechanism in HfO2-based resistive random access memories (ReRAM) with TiN(30 nm)HfO2(5 nm)Hf(10 nm)TiN(30 nm) stacks. Based on experimental I-V characteristics of bipolar HfO2-based ReRAM, we extracted QPC model parameters related to the conduction mechanism in several devices in order to make a statistical study. In addition, we investigated the temperature effect on the conduction mechanism and compared it with the QPC model. Based on these experimental results, we show that the QPC model agrees well with the conduction behavior of HfO2-based ReRAM memory cells.

  2. Generation-based memory synchronization in a multiprocessor system with weakly consistent memory accesses

    DOEpatents

    Ohmacht, Martin

    2014-09-09

    In a multiprocessor system, a central memory synchronization module coordinates memory synchronization requests responsive to memory access requests in flight, a generation counter, and a reclaim pointer. The central module communicates via point-to-point communication. The module includes a global OR reduce tree for each memory access requesting device, for detecting memory access requests in flight. An interface unit is implemented associated with each processor requesting synchronization. The interface unit includes multiple generation completion detectors. The generation count and reclaim pointer do not pass one another.

  3. Low power switching of Si-doped Ta2O5 resistive random access memory for high density memory application

    NASA Astrophysics Data System (ADS)

    Kim, Beom Yong; Jeung Lee, Kee; Ock Chung, Su; Gil Kim, Soo; Ko, Young Seok; Kim, Hyeong Soo

    2016-04-01

    We report, for the first time, the resistive switching properties of Si-doped Ta2O5 grown by atomic layer deposition (ALD). The reduced switching current, improved on/off current ratio, and excellent endurance property are demonstrated in the Si-doped Ta2O5 resistive random access memory (ReRAM) devices of 50 nm tech node. The switching mechanism for the Si-doped Ta2O5 resistor is discussed. Si dopants enable switching layer to have conformal distribution of oxygen vacancy and easily form conductive filament. This leads to higher on/off current ratio at even low operation current of 5-10 µA. Finally, one selector-one resistor (1S1R) ReRAM was developed for large cell array application. For the optimized 1S1R stack, 0.2 µA of off current and 5.0 of on/off current ratio were successfully achieved at 10 µA of low operation current.

  4. Influence of ultraviolet irradiation on data retention characteristics in resistive random access memory

    NASA Astrophysics Data System (ADS)

    Kimura, K.; Ohmi, K.; Kishida, S.; Kinoshita, K.

    2016-03-01

    With increasing density of memory devices, the issue of generating soft errors by cosmic rays is becoming more and more serious. Therefore, the irradiation resistance of resistance random access memory (ReRAM) to cosmic radiation has to be elucidated for practical use. In this paper, we investigated the data retention characteristics of ReRAM against ultraviolet irradiation with a Pt/NiO/ITO structure. Soft errors were confirmed to be caused by ultraviolet irradiation in both low- and high-resistance states. An analysis of the wavelength dependence of light irradiation on data retention characteristics suggested that electronic excitation from the valence to the conduction band and to the energy level generated due to the introduction of oxygen vacancies caused the errors. Based on a statistically estimated soft error rates, the errors were suggested to be caused by the cohesion and dispersion of oxygen vacancies owing to the generation of electron-hole pairs and valence changes by the ultraviolet irradiation.

  5. Phase-change Random Access Memory: A Scalable Technology

    SciTech Connect

    Raoux, S.; Burr, G; Breitwisch, M; Rettner, C; Chen, Y; Shelby, R; Salinga, M; Krebs, D; Chen, S; Lung, H

    2008-01-01

    Nonvolatile RAM using resistance contrast in phase-change materials [or phase-change RAM (PCRAM)] is a promising technology for future storage-class memory. However, such a technology can succeed only if it can scale smaller in size, given the increasingly tiny memory cells that are projected for future technology nodes (i.e., generations). We first discuss the critical aspects that may affect the scaling of PCRAM, including materials properties, power consumption during programming and read operations, thermal cross-talk between memory cells, and failure mechanisms. We then discuss experiments that directly address the scaling properties of the phase-change materials themselves, including studies of phase transitions in both nanoparticles and ultrathin films as a function of particle size and film thickness. This work in materials directly motivated the successful creation of a series of prototype PCRAM devices, which have been fabricated and tested at phase-change material cross-sections with extremely small dimensions as low as 3 nm x 20 nm. These device measurements provide a clear demonstration of the excellent scaling potential offered by this technology, and they are also consistent with the scaling behavior predicted by extensive device simulations. Finally, we discuss issues of device integration and cell design, manufacturability, and reliability.

  6. -based electrochemical metallization ReRAM application

    NASA Astrophysics Data System (ADS)

    Chin, Fun-Tat; Lin, Yu-Hsien; You, Hsin-Chiang; Yang, Wen-Luh; Lin, Li-Min; Hsiao, Yu-Ping; Ko, Chum-Min; Chao, Tien-Sheng

    2014-10-01

    This study investigates an advanced copper (Cu) chemical displacement technique (CDT) with varying the chemical displacement time for fabricating Cu/SiO2-stacked resistive random-access memory (ReRAM). Compared with other Cu deposition methods, this CDT easily controls the interface of the Cu-insulator, the switching layer thickness, and the immunity of the Cu etching process, assisting the 1-transistor-1-ReRAM (1T-1R) structure and system-on-chip integration. The modulated shape of the Cu-SiO2 interface and the thickness of the SiO2 layer obtained by CDT-based Cu deposition on SiO2 were confirmed by scanning electron microscopy and atomic force microscopy. The CDT-fabricated Cu/SiO2-stacked ReRAM exhibited lower operation voltages and more stable data retention characteristics than the control Cu/SiO2-stacked sample. As the Cu CDT processing time increased, the forming and set voltages of the CDT-fabricated Cu/SiO2-stacked ReRAM decreased. Conversely, decreasing the processing time reduced the on-state current and reset voltage while increasing the endurance switching cycle time. Therefore, the switching characteristics were easily modulated by Cu CDT, yielding a high performance electrochemical metallization (ECM)-type ReRAM.

  7. BCH codes for large IC random-access memory systems

    NASA Technical Reports Server (NTRS)

    Lin, S.; Costello, D. J., Jr.

    1983-01-01

    In this report some shortened BCH codes for possible applications to large IC random-access memory systems are presented. These codes are given by their parity-check matrices. Encoding and decoding of these codes are discussed.

  8. Radiation Effects of Commercial Resistive Random Access Memories

    NASA Technical Reports Server (NTRS)

    Chen, Dakai; LaBel, Kenneth; Berg, Melanie; Wilcox, Edward; Kim, Hak; Phan, Anthony; Figueiredo, Marco; Buchner, Stephen; Khachatrian, Ani; Roche, Nicolas

    2014-01-01

    We present results for the single-event effect response of commercial production-level resistive random access memories. We found that the resistive memory arrays are immune to heavy ion-induced upsets. However, the devices were susceptible to single-event functional interrupts, due to upsets from the control circuits. The intrinsic radiation tolerant nature of resistive memory makes the technology an attractive consideration for future space applications.

  9. The Dynamics of Access to Groups in Working Memory

    ERIC Educational Resources Information Center

    Farrell, Simon; Lelievre, Anna

    2012-01-01

    The finding that participants leave a pause between groups when attempting serial recall of temporally grouped lists has been taken to indicate access to a hierarchical representation of the list in working memory. An alternative explanation is that the dynamics of serial recall solely reflect output (rather than memorial) processes, with the…

  10. SQL-RAMS

    NASA Technical Reports Server (NTRS)

    Alfaro, Victor O.; Casey, Nancy J.

    2005-01-01

    SQL-RAMS (where "SQL" signifies Structured Query Language and "RAMS" signifies Rocketdyne Automated Management System) is a successor to the legacy version of RAMS -- a computer program used to manage all work, nonconformance, corrective action, and configuration management on rocket engines and ground support equipment at Stennis Space Center. The legacy version resided in the File-Maker Pro software system and was constructed in modules that could act as standalone programs. There was little or no integration among modules. Because of limitations on file-management capabilities in FileMaker Pro, and because of difficulty of integration of FileMaker Pro with other software systems for exchange of data using such industry standards as SQL, the legacy version of RAMS proved to be limited, and working to circumvent its limitations too time-consuming. In contrast, SQL-RAMS is an integrated SQL-server-based program that supports all data-exchange software industry standards. Whereas in the legacy version, it was necessary to access individual modules to gain insight into a particular workstatus document, SQL-RAMS provides access through a single-screen presentation of core modules. In addition, SQL-RAMS enables rapid and efficient filtering of displayed statuses by predefined categories and test numbers. SQL-RAMS is rich in functionality and encompasses significant improvements over the legacy system. It provides users the ability to perform many tasks, which in the past required administrator intervention. Additionally, many of the design limitations have been corrected, allowing for a robust application that is user centric.

  11. SQL-RAMS

    NASA Technical Reports Server (NTRS)

    Alfaro, Victor O.; Casey, Nancy J.

    2005-01-01

    SQL-RAMS (where "SQL" signifies Structured Query Language and "RAMS" signifies Rocketdyne Automated Management System) is a successor to the legacy version of RAMS a computer program used to manage all work, nonconformance, corrective action, and configuration management on rocket engines and ground support equipment at Stennis Space Center. The legacy version resided in the FileMaker Pro software system and was constructed in modules that could act as stand-alone programs. There was little or no integration among modules. Because of limitations on file-management capabilities in FileMaker Pro, and because of difficulty of integration of FileMaker Pro with other software systems for exchange of data using such industry standards as SQL, the legacy version of RAMS proved to be limited, and working to circumvent its limitations too time-consuming. In contrast, SQL-RAMS is an integrated SQL-server-based program that supports all data-exchange software industry standards. Whereas in the legacy version, it was necessary to access individual modules to gain insight to a particular work-status documents, SQL-RAMS provides access through a single-screen presentation of core modules. In addition, SQL-RAMS enable rapid and efficient filtering of displayed statuses by predefined categories and test numbers. SQL-RAMS is rich in functionality and encompasses significant improvements over the legacy system. It provides users the ability to perform many tasks which in the past required administrator intervention. Additionally many of the design limitations have been corrected allowing for a robust application that is user centric.

  12. Guideline model for the bias-scheme-dependent power consumption of a resistive random access memory crossbar array

    NASA Astrophysics Data System (ADS)

    Sun, Wookyung; Choi, Sujin; Lim, Hyein; Shin, Hyungsoon

    2016-04-01

    The 1/2 and 1/3 bias schemes are commonly used to select a cell in a resistive random access memory (ReRAM) crossbar array. The 1/3 bias scheme is advantageous in terms of its write margin but typically requires a higher power consumption than the 1/2 bias scheme. The power consumption of ReRAM can vary according to the nonlinearity of the selector device. In this paper, we propose a power guideline model that suggests selector nonlinearity requirements to guarantee a lower power consumption for the 1/3 bias scheme than for the 1/2 bias scheme. Therefore, the selector nonlinearity requirements for the low power consumption of the 1/3 bias scheme can be immediately obtained using this guideline model without simulation.

  13. Direct access inter-process shared memory

    DOEpatents

    Brightwell, Ronald B; Pedretti, Kevin; Hudson, Trammell B

    2013-10-22

    A technique for directly sharing physical memory between processes executing on processor cores is described. The technique includes loading a plurality of processes into the physical memory for execution on a corresponding plurality of processor cores sharing the physical memory. An address space is mapped to each of the processes by populating a first entry in a top level virtual address table for each of the processes. The address space of each of the processes is cross-mapped into each of the processes by populating one or more subsequent entries of the top level virtual address table with the first entry in the top level virtual address table from other processes.

  14. Memory for recently accessed visual attributes.

    PubMed

    Jiang, Yuhong V; Shupe, Joshua M; Swallow, Khena M; Tan, Deborah H

    2016-08-01

    Recent reports have suggested that the attended features of an item may be rapidly forgotten once they are no longer relevant for an ongoing task (attribute amnesia). This finding relies on a surprise memory procedure that places high demands on declarative memory. We used intertrial priming to examine whether the representation of an item's identity is lost completely once it becomes task irrelevant. If so, then the identity of a target on one trial should not influence performance on the next trial. In 3 experiments, we replicated the finding that a target's identity is poorly recognized in a surprise memory test. However, we also observed location and identity repetition priming across consecutive trials. These data suggest that, although explicit recognition on a surprise memory test may be impaired, some information about a particular target's identity can be retained after it is no longer needed for a task. (PsycINFO Database Record PMID:26844575

  15. Scaling Linear Algebra Kernels using Remote Memory Access

    SciTech Connect

    Krishnan, Manoj Kumar; Lewis, Robert R.; Vishnu, Abhinav

    2010-09-13

    This paper describes the scalability of linear algebra kernels based on remote memory access approach. The current approach differs from the other linear algebra algorithms by the explicit use of shared memory and remote memory access (RMA) communication rather than message passing. It is suitable for clusters and scalable shared memory systems. The experimental results on large scale systems (Linux-Infiniband cluster, Cray XT) demonstrate consistent performance advantages over ScaLAPACK suite, the leading implementation of parallel linear algebra algorithms used today. For example, on a Cray XT4 for a matrix size of 102400, our RMA-based matrix multiplication achieved over 55 teraflops while ScaLAPACK’s pdgemm measured close to 42 teraflops on 10000 processes.

  16. A Cerebellar-model Associative Memory as a Generalized Random-access Memory

    NASA Technical Reports Server (NTRS)

    Kanerva, Pentti

    1989-01-01

    A versatile neural-net model is explained in terms familiar to computer scientists and engineers. It is called the sparse distributed memory, and it is a random-access memory for very long words (for patterns with thousands of bits). Its potential utility is the result of several factors: (1) a large pattern representing an object or a scene or a moment can encode a large amount of information about what it represents; (2) this information can serve as an address to the memory, and it can also serve as data; (3) the memory is noise tolerant--the information need not be exact; (4) the memory can be made arbitrarily large and hence an arbitrary amount of information can be stored in it; and (5) the architecture is inherently parallel, allowing large memories to be fast. Such memories can become important components of future computers.

  17. 75 FR 14467 - In the Matter of: Certain Dynamic Random Access Memory Semiconductors and Products Containing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-25

    ... COMMISSION In the Matter of: Certain Dynamic Random Access Memory Semiconductors and Products Containing Same... random access memory semiconductors and products containing same, including memory modules, by reason of... after importation of certain dynamic random access memory semiconductors or products containing the...

  18. Direct memory access transfer completion notification

    DOEpatents

    Archer, Charles J.; Blocksome, Michael A.; Parker, Jeffrey J.

    2011-02-15

    DMA transfer completion notification includes: inserting, by an origin DMA engine on an origin node in an injection first-in-first-out (`FIFO`) buffer, a data descriptor for an application message to be transferred to a target node on behalf of an application on the origin node; inserting, by the origin DMA engine, a completion notification descriptor in the injection FIFO buffer after the data descriptor for the message, the completion notification descriptor specifying a packet header for a completion notification packet; transferring, by the origin DMA engine to the target node, the message in dependence upon the data descriptor; sending, by the origin DMA engine, the completion notification packet to a local reception FIFO buffer using a local memory FIFO transfer operation; and notifying, by the origin DMA engine, the application that transfer of the message is complete in response to receiving the completion notification packet in the local reception FIFO buffer.

  19. Magnetic Random Access Memory (MRAM) Device Development

    SciTech Connect

    Cerjan, C; Law, B P

    2000-01-18

    The recent discovery of materials that have anomalous magneto-resistive properties has generated renewed commercial interest in metal-based fast memory storage as an alternative to the currently used semiconductor-based devices. One particularly promising ternary alloy, fabricated at LLNL, appeared to have exceptional field response. This proposal extended the investigation of this class of materials by examining the scaling properties of test structures made from this material that could definitively verify the preliminary observations of high field sensitivity. Although the expected scaling was observed, technical issues, such as excessive oxidation, prevented a definitive assessment of the effect. Despite the difficulties encountered, several test structures demonstrated superior performance in a ''spin-valve'' configuration that might have applications for very high density recording heads.

  20. Access Analysis-Based Tight Localization of Abstract Memories

    NASA Astrophysics Data System (ADS)

    Oh, Hakjoo; Brutschy, Lucas; Yi, Kwangkeun

    On-the-fly localization of abstract memory states is vital for economical abstract interpretation of imperative programs. Such localization is sometimes called "abstract garbage collection" or "framing". In this article we present a new memory localization technique that is more effective than the conventional reachability-based approach. Our technique is based on a key observation that collecting the reachable memory parts is too conservative and the accessed parts are usually tiny subsets of the reachable. Our technique first estimates, by an efficient pre-analysis, the set of locations that will be accessed during the analysis of each code block. Then the main analysis uses the access-set results to trim the memory entries before analyzing code blocks. In experiments with an industrial-strength global C static analyzer, the technique is applied right before analyzing each procedure's body and reduces the average analysis time and memory by 92.1% and 71.2%, respectively, without sacrificing the analysis precision. Localizing more frequently such as at loop bodies and basic blocks as well as procedure bodies, the generalized localization additionally reduces analysis time by an average of 31.8%.

  1. Quantifying Locality in the Memory Access Patterns of HPCApplications

    SciTech Connect

    Weinberg, Jonathan; Snavely, Allan; McCracken, Michael O.; Strohmaier, Erich

    2005-07-25

    Several benchmarks for measuring memory performance of HPC systems along dimensions of spatial and temporal memory locality have recently been proposed. However, little is understood about the relationships of these benchmarks to real applications and to each other. In this paper, we propose a methodology for producing architecture-neutral characterizations of the spatial and temporal locality exhibited by the memory access patterns of applications. We demonstrate that the results track intuitive notions of spatial and temporal locality on several synthetic and application benchmarks. We employ the methodology to analyze the memory performance components of the HPC Challenge Benchmarks, the Apex-MAP benchmark, and their relationships to each other and other benchmarks and applications. We show that this analysis can be used to both increase understanding of the benchmarks and enhance their usefulness by mapping them, along with applications, to a 2-D space along axes of spatial and temporal locality.

  2. Kokkos: Enabling manycore performance portability through polymorphic memory access patterns

    SciTech Connect

    Carter Edwards, H.; Trott, Christian R.; Sunderland, Daniel

    2014-07-22

    The manycore revolution can be characterized by increasing thread counts, decreasing memory per thread, and diversity of continually evolving manycore architectures. High performance computing (HPC) applications and libraries must exploit increasingly finer levels of parallelism within their codes to sustain scalability on these devices. We found that a major obstacle to performance portability is the diverse and conflicting set of constraints on memory access patterns across devices. Contemporary portable programming models address manycore parallelism (e.g., OpenMP, OpenACC, OpenCL) but fail to address memory access patterns. The Kokkos C++ library enables applications and domain libraries to achieve performance portability on diverse manycore architectures by unifying abstractions for both fine-grain data parallelism and memory access patterns. In this paper we describe Kokkos’ abstractions, summarize its application programmer interface (API), present performance results for unit-test kernels and mini-applications, and outline an incremental strategy for migrating legacy C++ codes to Kokkos. Furthermore, the Kokkos library is under active research and development to incorporate capabilities from new generations of manycore architectures, and to address a growing list of applications and domain libraries.

  3. Kokkos: Enabling manycore performance portability through polymorphic memory access patterns

    DOE PAGESBeta

    Carter Edwards, H.; Trott, Christian R.; Sunderland, Daniel

    2014-07-22

    The manycore revolution can be characterized by increasing thread counts, decreasing memory per thread, and diversity of continually evolving manycore architectures. High performance computing (HPC) applications and libraries must exploit increasingly finer levels of parallelism within their codes to sustain scalability on these devices. We found that a major obstacle to performance portability is the diverse and conflicting set of constraints on memory access patterns across devices. Contemporary portable programming models address manycore parallelism (e.g., OpenMP, OpenACC, OpenCL) but fail to address memory access patterns. The Kokkos C++ library enables applications and domain libraries to achieve performance portability on diversemore » manycore architectures by unifying abstractions for both fine-grain data parallelism and memory access patterns. In this paper we describe Kokkos’ abstractions, summarize its application programmer interface (API), present performance results for unit-test kernels and mini-applications, and outline an incremental strategy for migrating legacy C++ codes to Kokkos. Furthermore, the Kokkos library is under active research and development to incorporate capabilities from new generations of manycore architectures, and to address a growing list of applications and domain libraries.« less

  4. Integrated, nonvolatile, high-speed analog random access memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R. (Inventor); Wu, Jiin-Chuan (Inventor); Stadler, Henry L. (Inventor)

    1994-01-01

    This invention provides an integrated, non-volatile, high-speed random access memory. A magnetically switchable ferromagnetic or ferrimagnetic layer is sandwiched between an electrical conductor which provides the ability to magnetize the magnetically switchable layer and a magneto resistive or Hall effect material which allows sensing the magnetic field which emanates from the magnetization of the magnetically switchable layer. By using this integrated three-layer form, the writing process, which is controlled by the conductor, is separated from the storage medium in the magnetic layer and from the readback process which is controlled by the magnetoresistive layer. A circuit for implementing the memory in CMOS or the like is disclosed.

  5. Magnet/Hall-Effect Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Wu, Jiin-Chuan; Stadler, Henry L.; Katti, Romney R.

    1991-01-01

    In proposed magnet/Hall-effect random-access memory (MHRAM), bits of data stored magnetically in Perm-alloy (or equivalent)-film memory elements and read out by using Hall-effect sensors to detect magnetization. Value of each bit represented by polarity of magnetization. Retains data for indefinite time or until data rewritten. Speed of Hall-effect sensors in MHRAM results in readout times of about 100 nanoseconds. Other characteristics include high immunity to ionizing radiation and storage densities of order 10(Sup6)bits/cm(Sup 2) or more.

  6. Performance Evaluation of Remote Memory Access (RMA) Programming on Shared Memory Parallel Computers

    NASA Technical Reports Server (NTRS)

    Jin, Hao-Qiang; Jost, Gabriele; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    The purpose of this study is to evaluate the feasibility of remote memory access (RMA) programming on shared memory parallel computers. We discuss different RMA based implementations of selected CFD application benchmark kernels and compare them to corresponding message passing based codes. For the message-passing implementation we use MPI point-to-point and global communication routines. For the RMA based approach we consider two different libraries supporting this programming model. One is a shared memory parallelization library (SMPlib) developed at NASA Ames, the other is the MPI-2 extensions to the MPI Standard. We give timing comparisons for the different implementation strategies and discuss the performance.

  7. Non-Volatile Memory Technology Symposium 2001: Proceedings

    NASA Technical Reports Server (NTRS)

    Aranki, Nazeeh; Daud, Taher; Strauss, Karl

    2001-01-01

    This publication contains the proceedings for the Non-Volatile Memory Technology Symposium 2001 that was held on November 7-8, 2001 in San Diego, CA. The proceedings contains a a wide range of papers that cover current and new memory technologies including Flash memories, Magnetic Random Access Memories (MRAM and GMRAM), Ferro-electric RAM (FeRAM), and Chalcogenide RAM (CRAM). The papers presented in the proceedings address the use of these technologies for space applications as well as radiation effects and packaging issues.

  8. 76 FR 73676 - Certain Dynamic Random Access Memory Devices, and Products Containing Same; Receipt of Complaint...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-29

    ... COMMISSION Certain Dynamic Random Access Memory Devices, and Products Containing Same; Receipt of Complaint... complaint entitled In Re Certain Dynamic Random Access Memory Devices, and Products Containing Same, DN 2859... within the United States after importation of certain dynamic random access memory devices, and...

  9. 76 FR 80964 - Certain Dynamic Random Access Memory Devices, and Products Containing Same; Institution of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-27

    ... COMMISSION Certain Dynamic Random Access Memory Devices, and Products Containing Same; Institution of... States after importation of certain dynamic random access memory devices, and products containing same by... dynamic random access memory devices, and products containing same that infringe one or more of claims...

  10. Method and device for maximizing memory system bandwidth by accessing data in a dynamically determined order

    NASA Technical Reports Server (NTRS)

    Wulf, William A. (Inventor); McKee, Sally A. (Inventor); Klenke, Robert (Inventor); Schwab, Andrew J. (Inventor); Moyer, Stephen A. (Inventor); Aylor, James (Inventor); Hitchcock, Charles Young (Inventor)

    2000-01-01

    A data processing system is disclosed which comprises a data processor and memory control device for controlling the access of information from the memory. The memory control device includes temporary storage and decision ability for determining what order to execute the memory accesses. The compiler detects the requirements of the data processor and selects the data to stream to the memory control device which determines a memory access order. The order in which to access said information is selected based on the location of information stored in the memory. The information is repeatedly accessed from memory and stored in the temporary storage until all streamed information is accessed. The information is stored until required by the data processor. The selection of the order in which to access information maximizes bandwidth and decreases the retrieval time.

  11. Nonvolatile GaAs Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.; Stadler, Henry L.; Wu, Jiin-Chuan

    1994-01-01

    Proposed random-access integrated-circuit electronic memory offers nonvolatile magnetic storage. Bits stored magnetically and read out with Hall-effect sensors. Advantages include short reading and writing times and high degree of immunity to both single-event upsets and permanent damage by ionizing radiation. Use of same basic material for both transistors and sensors simplifies fabrication process, with consequent benefits in increased yield and reduced cost.

  12. Implementation of Ferroelectric Memories for Space Applications

    NASA Technical Reports Server (NTRS)

    Philpy, Stephen C.; Derbenwick, Gary F.; Kamp, David A.; Isaacson, Alan F.

    2000-01-01

    Ferroelectric random access semiconductor memories (FeRAMs) are an ideal nonvolatile solution for space applications. These memories have low power performance, high endurance and fast write times. By combining commercial ferroelectric memory technology with radiation hardened CMOS technology, nonvolatile semiconductor memories for space applications can be attained. Of the few radiation hardened semiconductor manufacturers, none have embraced the development of radiation hardened FeRAMs, due a limited commercial space market and funding limitations. Government funding may be necessary to assure the development of radiation hardened ferroelectric memories for space applications.

  13. If memory serves, will language? Later verbal accessibility of early memories.

    PubMed

    Bauer, P J; Kroupina, M G; Schwade, J A; Dropik, P L; Wewerka, S S

    1998-01-01

    Of major interest to those concerned with early mnemonic process and function is the question of whether early memories likely encoded without the benefit of language later are accessible to verbal report. In the context of a controlled laboratory study, we examined this question in children who were 16 and 20 months at the time of exposure to specific target events and who subsequently were tested for their memories of the events after a delay of either 6 or 12 months (at 22-32 months) and then again at 3 years. At the first delayed-recall test, children evidenced memory both nonverbally and verbally. Nonverbal mnemonic expression was related to age at the time of test; verbal mnemonic expression was related to verbal fluency at the time of test. At the second delayed-recall test, children evidenced continued accessibility of their early memories. Verbal mnemonic expression was related to previous mnemonic expression, both nonverbal and verbal, each of which contributed unique variance. The relevance of these findings on memory for controlled laboratory events for issues of memory for traumatic experiences is discussed. PMID:9886220

  14. Cost-effective, transfer-free, flexible resistive random access memory using laser-scribed reduced graphene oxide patterning technology.

    PubMed

    Tian, He; Chen, Hong-Yu; Ren, Tian-Ling; Li, Cheng; Xue, Qing-Tang; Mohammad, Mohammad Ali; Wu, Can; Yang, Yi; Wong, H-S Philip

    2014-06-11

    Laser scribing is an attractive reduced graphene oxide (rGO) growth and patterning technology because the process is low-cost, time-efficient, transfer-free, and flexible. Various laser-scribed rGO (LSG) components such as capacitors, gas sensors, and strain sensors have been demonstrated. However, obstacles remain toward practical application of the technology where all the components of a system are fabricated using laser scribing. Memory components, if developed, will substantially broaden the application space of low-cost, flexible electronic systems. For the first time, a low-cost approach to fabricate resistive random access memory (ReRAM) using laser-scribed rGO as the bottom electrode is experimentally demonstrated. The one-step laser scribing technology allows transfer-free rGO synthesis directly on flexible substrates or non-flat substrates. Using this time-efficient laser-scribing technology, the patterning of a memory-array area up to 100 cm(2) can be completed in 25 min. Without requiring the photoresist coating for lithography, the surface of patterned rGO remains as clean as its pristine state. Ag/HfOx/LSG ReRAM using laser-scribing technology is fabricated in this work. Comprehensive electrical characteristics are presented including forming-free behavior, stable switching, reasonable reliability performance and potential for 2-bit storage per memory cell. The results suggest that laser-scribing technology can potentially produce more cost-effective and time-effective rGO-based circuits and systems for practical applications. PMID:24801736

  15. Size-dependent resistive switching properties of the active region in nickel nitride-based crossbar array resistive random access memory.

    PubMed

    Kim, Hee-Dong; Yun, Min Ju; Hong, Seok Man; Kim, Tae Geun

    2014-12-01

    The size-dependent resistive switching (RS) properties of the active region in a 1 x 1 NiN-based crossbar array (CBA) resistive random access memory (ReRAM) are investigated in the range of 2 x 2 μm2 to 8 x 8 μm2. In the forming test, the forming voltage is reduced by decreasing the cell size of the active region. Compared to the 8 x 8 μm2 CBA ReRAM, the forming voltage of the 2 x 2 μm2 CBA ReRAM was reduced from 8 V to 6.2 V. In addition, V(SET/RESET) and the current for the reset operation are reduced in the current-voltage (I-V) results by reducing the cell size, while the current at a high-resistance state (HRS) is increased. As a result, the current ratio between the HRS and a low-resistance state (LRS) is reduced. On the other hand, the variation of V(SET) for I-V curves repetitively acquired 100 times is decreased by decreasing the cell size in the reliability test. Further, the current at the HRS for the 2 x 2 μm2 CBA ReRAM is the most stable with the smallest current variation for 1000 s in the retention test. These results show that reducing the active region in the CBA ReRAM structure is effective for improving the reliability of ReRAM cells because it reduces the operating voltage and current as well as the variation of V(SET) and the current at the HRS. PMID:25971015

  16. Vortex-Core Reversal Dynamics: Towards Vortex Random Access Memory

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Koog

    2011-03-01

    An energy-efficient, ultrahigh-density, ultrafast, and nonvolatile solid-state universal memory is a long-held dream in the field of information-storage technology. The magnetic random access memory (MRAM) along with a spin-transfer-torque switching mechanism is a strong candidate-means of realizing that dream, given its nonvolatility, infinite endurance, and fast random access. Magnetic vortices in patterned soft magnetic dots promise ground-breaking applications in information-storage devices, owing to the very stable twofold ground states of either their upward or downward core magnetization orientation and plausible core switching by in-plane alternating magnetic fields or spin-polarized currents. However, two technologically most important but very challenging issues --- low-power recording and reliable selection of each memory cell with already existing cross-point architectures --- have not yet been resolved for the basic operations in information storage, that is, writing (recording) and readout. Here, we experimentally demonstrate a magnetic vortex random access memory (VRAM) in the basic cross-point architecture. This unique VRAM offers reliable cell selection and low-power-consumption control of switching of out-of-plane core magnetizations using specially designed rotating magnetic fields generated by two orthogonal and unipolar Gaussian-pulse currents along with optimized pulse width and time delay. Our achievement of a new device based on a new material, that is, a medium composed of patterned vortex-state disks, together with the new physics on ultrafast vortex-core switching dynamics, can stimulate further fruitful research on MRAMs that are based on vortex-state dot arrays.

  17. Oxide thickness dependence of resistive switching characteristics for Ni/HfOx/Pt resistive random access memory device

    NASA Astrophysics Data System (ADS)

    Ito, Daisuke; Hamada, Yoshihumi; Otsuka, Shintaro; Shimizu, Tomohiro; Shingubara, Shoso

    2015-06-01

    The switching process of the conductive filament formed in Ni/HfOx/Pt resistive random access memory (ReRAM) devices were studied. We evaluated the oxide thickness dependence and temperature dependence of voltage for the Forming, Set and Reset operations for HfOx layers whose thickness are between 3.3 and 6.5 nm. The resistance of conductive filaments showed typical metallic behavior, which suggests Ni filament formation in the HfOx layer. There is a clear dependence of switching voltages for the Set and Reset processes on oxide thickness, which implies that the formation and rupture of conductive filaments occur in the entire thickness range of the HfOx layer. This finding differs from that of a previous study by Yang, which suggests the existence of a constant-thickness switching region. It is suggested that the thickness of the switching region in HfOx may be larger than 6.5 nm.

  18. Complex dynamics of semantic memory access in reading.

    PubMed

    Baggio, Giosué; Fonseca, André

    2012-02-01

    Understanding a word in context relies on a cascade of perceptual and conceptual processes, starting with modality-specific input decoding, and leading to the unification of the word's meaning into a discourse model. One critical cognitive event, turning a sensory stimulus into a meaningful linguistic sign, is the access of a semantic representation from memory. Little is known about the changes that activating a word's meaning brings about in cortical dynamics. We recorded the electroencephalogram (EEG) while participants read sentences that could contain a contextually unexpected word, such as 'cold' in 'In July it is very cold outside'. We reconstructed trajectories in phase space from single-trial EEG time series, and we applied three nonlinear measures of predictability and complexity to each side of the semantic access boundary, estimated as the onset time of the N400 effect evoked by critical words. Relative to controls, unexpected words were associated with larger prediction errors preceding the onset of the N400. Accessing the meaning of such words produced a phase transition to lower entropy states, in which cortical processing becomes more predictable and more regular. Our study sheds new light on the dynamics of information flow through interfaces between sensory and memory systems during language processing. PMID:21715401

  19. Administering an epoch initiated for remote memory access

    SciTech Connect

    Blocksome, Michael A; Miller, Douglas R

    2014-03-18

    Methods, systems, and products are disclosed for administering an epoch initiated for remote memory access that include: initiating, by an origin application messaging module on an origin compute node, one or more data transfers to a target compute node for the epoch; initiating, by the origin application messaging module after initiating the data transfers, a closing stage for the epoch, including rejecting any new data transfers after initiating the closing stage for the epoch; determining, by the origin application messaging module, whether the data transfers have completed; and closing, by the origin application messaging module, the epoch if the data transfers have completed.

  20. Administering an epoch initiated for remote memory access

    DOEpatents

    Blocksome, Michael A; Miller, Douglas R

    2012-10-23

    Methods, systems, and products are disclosed for administering an epoch initiated for remote memory access that include: initiating, by an origin application messaging module on an origin compute node, one or more data transfers to a target compute node for the epoch; initiating, by the origin application messaging module after initiating the data transfers, a closing stage for the epoch, including rejecting any new data transfers after initiating the closing stage for the epoch; determining, by the origin application messaging module, whether the data transfers have completed; and closing, by the origin application messaging module, the epoch if the data transfers have completed.

  1. Administering an epoch initiated for remote memory access

    DOEpatents

    Blocksome, Michael A.; Miller, Douglas R.

    2013-01-01

    Methods, systems, and products are disclosed for administering an epoch initiated for remote memory access that include: initiating, by an origin application messaging module on an origin compute node, one or more data transfers to a target compute node for the epoch; initiating, by the origin application messaging module after initiating the data transfers, a closing stage for the epoch, including rejecting any new data transfers after initiating the closing stage for the epoch; determining, by the origin application messaging module, whether the data transfers have completed; and closing, by the origin application messaging module, the epoch if the data transfers have completed.

  2. Finding Oxygen Reservoir by Using Extremely Small Test Cell Structure for Resistive Random Access Memory with Replaceable Bottom Electrode

    PubMed Central

    Kinoshita, Kentaro; Koh, Sang-Gyu; Moriyama, Takumi; Kishida, Satoru

    2015-01-01

    Although the presence of an oxygen reservoir (OR) is assumed in many models that explain resistive switching of resistive random access memory (ReRAM) with electrode/metal oxide (MO)/electrode structures, the location of OR is not clear. We have previously reported a method, which involved the use of an AFM cantilever, for preparing an extremely small ReRAM cell that has a removable bottom electrode (BE). In this study, we used this cell structure to specify the location of OR. Because an anode is often assumed to work as OR, we investigated the effect of changing anodes without changing the MO layer and the cathode on the occurrence of reset. It was found that the reset occurred independently of the catalytic ability and Gibbs free energy (ΔG) of the anode. Our proposed structure enabled to determine that the reset was caused by repairing oxygen vacancies of which a filament consists due to the migration of oxygen ions from the surrounding area when high ΔG anode metal is used, whereas by oxidizing the anode due to the migration of oxygen ions from the MO layer when low ΔG anode metal is used, suggesting the location of OR depends on ΔG of the anode. PMID:26689682

  3. Finding Oxygen Reservoir by Using Extremely Small Test Cell Structure for Resistive Random Access Memory with Replaceable Bottom Electrode.

    PubMed

    Kinoshita, Kentaro; Koh, Sang-Gyu; Moriyama, Takumi; Kishida, Satoru

    2015-01-01

    Although the presence of an oxygen reservoir (OR) is assumed in many models that explain resistive switching of resistive random access memory (ReRAM) with electrode/metal oxide (MO)/electrode structures, the location of OR is not clear. We have previously reported a method, which involved the use of an AFM cantilever, for preparing an extremely small ReRAM cell that has a removable bottom electrode (BE). In this study, we used this cell structure to specify the location of OR. Because an anode is often assumed to work as OR, we investigated the effect of changing anodes without changing the MO layer and the cathode on the occurrence of reset. It was found that the reset occurred independently of the catalytic ability and Gibbs free energy (ΔG) of the anode. Our proposed structure enabled to determine that the reset was caused by repairing oxygen vacancies of which a filament consists due to the migration of oxygen ions from the surrounding area when high ΔG anode metal is used, whereas by oxidizing the anode due to the migration of oxygen ions from the MO layer when low ΔG anode metal is used, suggesting the location of OR depends on ΔG of the anode. PMID:26689682

  4. Finding Oxygen Reservoir by Using Extremely Small Test Cell Structure for Resistive Random Access Memory with Replaceable Bottom Electrode

    NASA Astrophysics Data System (ADS)

    Kinoshita, Kentaro; Koh, Sang-Gyu; Moriyama, Takumi; Kishida, Satoru

    2015-12-01

    Although the presence of an oxygen reservoir (OR) is assumed in many models that explain resistive switching of resistive random access memory (ReRAM) with electrode/metal oxide (MO)/electrode structures, the location of OR is not clear. We have previously reported a method, which involved the use of an AFM cantilever, for preparing an extremely small ReRAM cell that has a removable bottom electrode (BE). In this study, we used this cell structure to specify the location of OR. Because an anode is often assumed to work as OR, we investigated the effect of changing anodes without changing the MO layer and the cathode on the occurrence of reset. It was found that the reset occurred independently of the catalytic ability and Gibbs free energy (ΔG) of the anode. Our proposed structure enabled to determine that the reset was caused by repairing oxygen vacancies of which a filament consists due to the migration of oxygen ions from the surrounding area when high ΔG anode metal is used, whereas by oxidizing the anode due to the migration of oxygen ions from the MO layer when low ΔG anode metal is used, suggesting the location of OR depends on ΔG of the anode.

  5. Resistive random access memory enabled by carbon nanotube crossbar electrodes.

    PubMed

    Tsai, Cheng-Lin; Xiong, Feng; Pop, Eric; Shim, Moonsub

    2013-06-25

    We use single-walled carbon nanotube (CNT) crossbar electrodes to probe sub-5 nm memory domains of thin AlOx films. Both metallic and semiconducting CNTs effectively switch AlOx bits between memory states with high and low resistance. The low-resistance state scales linearly with CNT series resistance down to ∼10 MΩ, at which point the ON-state resistance of the AlOx filament becomes the limiting factor. Dependence of switching behavior on the number of cross-points suggests a single channel to dominate the overall characteristics in multi-crossbar devices. We demonstrate ON/OFF ratios up to 5 × 10(5) and programming currents of 1 to 100 nA with few-volt set/reset voltages. Remarkably low reset currents enable a switching power of 10-100 nW and estimated switching energy as low as 0.1-10 fJ per bit. These results are essential for understanding the ultimate scaling limits of resistive random access memory at single-nanometer bit dimensions. PMID:23705675

  6. Efficient Memory Access with NumPy Global Arrays using Local Memory Access

    SciTech Connect

    Daily, Jeffrey A.; Berghofer, Dan C.

    2013-08-03

    This paper discusses the work completed working with Global Arrays of data on distributed multi-computer systems and improving their performance. The tasks completed were done at Pacific Northwest National Laboratory in the Science Undergrad Laboratory Internship program in the summer of 2013 for the Data Intensive Computing Group in the Fundamental and Computational Sciences DIrectorate. This work was done on the Global Arrays Toolkit developed by this group. This toolkit is an interface for programmers to more easily create arrays of data on networks of computers. This is useful because scientific computation is often done on large amounts of data sometimes so large that individual computers cannot hold all of it. This data is held in array form and can best be processed on supercomputers which often consist of a network of individual computers doing their computation in parallel. One major challenge for this sort of programming is that operations on arrays on multiple computers is very complex and an interface is needed so that these arrays seem like they are on a single computer. This is what global arrays does. The work done here is to use more efficient operations on that data that requires less copying of data to be completed. This saves a lot of time because copying data on many different computers is time intensive. The way this challenge was solved is when data to be operated on with binary operations are on the same computer, they are not copied when they are accessed. When they are on separate computers, only one set is copied when accessed. This saves time because of less copying done although more data access operations were done.

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

    PubMed

    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. PMID:24038631

  8. Ultimate multibit 1T-FeRAM with selectively nucleated grown single-grain PbZr0.52Ti0.48O3 for very-large-scale-integrated memory

    NASA Astrophysics Data System (ADS)

    Hyo Park, Jae; Kim, Hyung Yoon; Jang, Gil Su; Ahn, Donghwan; Joo, Seung Ki

    2016-02-01

    Controlling the grain-boundary of ferroelectric thin-film is significantly important for realizing ultimate multibit-FeRAM, when a ferroelectric thin-film deposited by radio-frequency reactive magnetron sputtering is integrated into silicon-based devices. A novel crystal-growth process of a ferroelectric thin-film using platinum (Pt)-seed matrix is developed for dividing the nucleation and growth of PbZr0.52Ti0.48O3 (PZT), which cannot be observed in the classical nucleation and growth of PZT. Locating artificial nucleation seeds using Pt-seeds in a desirable position enables one to obtain a large single-grain PZT (~40 μm) that is large enough to fabricate a field-effect transistor (FET)-type FeRAM. The fabricated FeRAM with a Pt/PZT/ZrTiO4(ZTO)/p-Si structure showed a wide memory window (~1.8 V), low operation voltage (~6 V), ultra-fast Program/Erase (P/E) switching speed (~10-7 s), and a stable multibit operation controlled by local polarization. In addition, the FeRAM showed no degradation even after cycling the P/E more than 1011 times in all multibit states, and the retention time was expected to have a wide memory window even after 10 years in all multibit states. These characteristics show great potential for the multi-bit FeRAM, which is difficult to expect a reliable operation with large grain-boundaries.

  9. Computational RAM implementation of MPEG-2 for real-time encoding

    NASA Astrophysics Data System (ADS)

    Le, Thinh M.; Snelgrove, W. M.; Panchanathan, Sethuraman

    1997-01-01

    In this paper, a computational random access memory (C*RAM) implementation of MPEG-2 video compression standard is presented. This implementation has the advantage of processing image/video data in parallel and directly in the frame buffers. Therefore, savings in execution time and I/O bandwidth due to massively parallel on-chip computation and reduction in the data transfer among chips is achieved. As a result, MPEG-2 video encoding can be realized in real-time on a programmable 64 Mb DRAM-based C*RAM.

  10. Performance analysis of STT-RAM with cross shaped free layer using Heusler alloys

    NASA Astrophysics Data System (ADS)

    Bharat Kumary, Tangudu; Ghosh, Bahniman; Awadhiya, Bhaskar; Verma, Ankit Kumar

    2016-01-01

    We have investigated the performance of a spin transfer torque random access memory (STT-RAM) cell with a cross shaped Heusler compound based free layer using micromagnetic simulations. We have designed a free layer using a Cobalt based Heusler compound. Simulation results clearly show that the switching time from one state to the other state has been reduced, also it has been found that the critical switching current density (to switch the magnetization of the free layer of the STT RAM cell) is reduced.

  11. Spin-Hall-assisted magnetic random access memory

    SciTech Connect

    Brink, A. van den Swagten, H. J. M.; Koopmans, B.; Cosemans, S.; Manfrini, M.; Van Roy, W.; Min, T.; Cornelissen, S.; Vaysset, A.; Departement elektrotechniek , KU Leuven, Kasteelpark Arenberg 10, B-3001 Heverlee

    2014-01-06

    We propose a write scheme for perpendicular spin-transfer torque magnetoresistive random-access memory that significantly reduces the required tunnel current density and write energy. A sub-nanosecond in-plane polarized spin current pulse is generated using the spin-Hall effect, disturbing the stable magnetic state. Subsequent switching using out-of-plane polarized spin current becomes highly efficient. Through evaluation of the Landau-Lifshitz-Gilbert equation, we quantitatively assess the viability of this write scheme for a wide range of system parameters. A typical example shows an eight-fold reduction in tunnel current density, corresponding to a fifty-fold reduction in write energy, while maintaining a 1 ns write time.

  12. Materials selection for oxide-based resistive random access memories

    SciTech Connect

    Guo, Yuzheng; Robertson, John

    2014-12-01

    The energies of atomic processes in resistive random access memories (RRAMs) are calculated for four typical oxides, HfO{sub 2}, TiO{sub 2}, Ta{sub 2}O{sub 5}, and Al{sub 2}O{sub 3}, to define a materials selection process. O vacancies have the lowest defect formation energy in the O-poor limit and dominate the processes. A band diagram defines the operating Fermi energy and O chemical potential range. It is shown how the scavenger metal can be used to vary the O vacancy formation energy, via controlling the O chemical potential, and the mean Fermi energy. The high endurance of Ta{sub 2}O{sub 5} RRAM is related to its more stable amorphous phase and the adaptive lattice rearrangements of its O vacancy.

  13. Complementary resistive switching behavior for conductive bridge random access memory

    NASA Astrophysics Data System (ADS)

    Zheng, Hao-Xuan; Chang, Ting-Chang; Chang, Kuan-Chang; Tsai, Tsung-Ming; Shih, Chih-Cheng; Zhang, Rui; Chen, Kai-Huang; Wang, Ming-Hui; Zheng, Jin-Cheng; Lo, Ikai; Wu, Cheng-Hsien; Tseng, Yi-Ting; Sze, Simon M.

    2016-06-01

    In this study, a structure of Pt/Cu18Si12O70/TiN has been investigated. By co-sputtering the Cu and SiO2 targets in the switching layer, we can measure the operation mechanism of complementary resistive switching (CRS). This differs from conventional conductive bridge random access memory (CBRAM) that tends to use Cu electrodes rather than Cu18Si12O70. By changing the voltage and compliance current, we can control device operating characteristics. Because Cu distributes differently in the device depending on this setting, the operating end can be located at either the top or bottom electrode. Device current–voltage (I–V) curves are used to demonstrate that the CRS in the CBRAM device is a double-electrode operation.

  14. Taxing Working Memory during Retrieval of Emotional Memories Does Not Reduce Memory Accessibility When Cued with Reminders

    PubMed Central

    van Schie, Kevin; Engelhard, Iris M.; van den Hout, Marcel A.

    2015-01-01

    Earlier studies have shown that when individuals recall an emotional memory while simultaneously doing a demanding dual-task [e.g., playing Tetris, mental arithmetic, making eye movements (EM)], this reduces self-reported vividness and emotionality of the memory. These effects have been found up to 1 week later, but have largely been confined to self-report ratings. This study examined whether this dual-tasking intervention reduces memory performance (i.e., accessibility of emotional memories). Undergraduates (N = 60) studied word-image pairs and rated the retrieved image on vividness and emotionality when cued with the word. Then they viewed the cues and recalled the images with or without making EM. Finally, they re-rated the images on vividness and emotionality. Additionally, fragments from images from all conditions were presented and participants identified which fragment was paired earlier with which cue. Findings showed no effect of the dual-task manipulation on self-reported ratings and latency responses. Several possible explanations for the lack of effects are discussed, but the cued recall procedure in our experiment seems to explain the absence of effects best. The study demonstrates boundaries to the effects of the “dual-tasking” procedure. PMID:25729370

  15. 0.6-1.0 V operation set/reset voltage (3 V) generator for three-dimensional integrated resistive random access memory and NAND flash hybrid solid-state drive

    NASA Astrophysics Data System (ADS)

    Tanaka, Masahiro; Hachiya, Shogo; Ishii, Tomoya; Ning, Sheyang; Tsurumi, Kota; Takeuchi, Ken

    2016-04-01

    A 0.6-1.0 V, 25.9 mm2 boost converter is proposed to generate resistive random access memory (ReRAM) write (set/reset) voltage for three-dimensional (3D) integrated ReRAM and NAND flash hybrid solid-state drive (SSD). The proposed boost converter uses an integrated area-efficient V BUF generation circuit to obtain short ReRAM sector write time, small circuit size, and small energy consumption simultaneously. In specific, the proposed boost converter reduces ReRAM sector write time by 65% compared with a conventional one-stage boost converter (Conventional 1) which uses 1.0 V operating voltage. On the other hand, by using the same ReRAM sector write time, the proposed boost converter reduces 49% circuit area and 46% energy consumption compared with a conventional two-stage boost converter (Conventional 2). In addition, by using the proposed boost converter, the operating voltage, V DD, can be reduced to 0.6 V. The lowest 159 nJ energy consumption can be obtained when V DD is 0.7 V.

  16. Accessibility versus Accuracy in Retrieving Spatial Memory: Evidence for Suboptimal Assumed Headings

    ERIC Educational Resources Information Center

    Yerramsetti, Ashok; Marchette, Steven A.; Shelton, Amy L.

    2013-01-01

    Orientation dependence in spatial memory has often been interpreted in terms of accessibility: Object locations are encoded relative to a reference orientation that affords the most accurate access to spatial memory. An open question, however, is whether people naturally use this "preferred" orientation whenever recalling the space. We…

  17. 75 FR 44989 - In the Matter of Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-30

    ... December 10, 2008, based on a complaint filed by Rambus, Inc. of Los Altos, California (``Rambus''). 73 FR... COMMISSION In the Matter of Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory... chips having synchronous dynamic random access memory controllers and product containing the same...

  18. The Cost of Accessing an Object's Feature Stored in Visual Working Memory

    PubMed Central

    Woodman, Geoffrey F.; Vecera, Shaun P.

    2010-01-01

    The effects of accessing or retrieving information held in working memory are poorly understood compared to what we know about the nature of information storage in this limited-capacity memory system. Previous studies of object-based attention have often relied upon memory-demanding tasks, and this work could indicate that accessing a piece of information in visual working memory may have deleterious effects upon the other representations being maintained. In the present study, we tested the hypothesis that accessing a feature of an object represented in visual working memory degrades the representations of the other stored objects’ features. Our findings support this hypothesis and point to important new questions about the nature of effects resulting from accessing information stored in visual working memory. PMID:21221413

  19. Optimizing NEURON Simulation Environment Using Remote Memory Access with Recursive Doubling on Distributed Memory Systems.

    PubMed

    Shehzad, Danish; Bozkuş, Zeki

    2016-01-01

    Increase in complexity of neuronal network models escalated the efforts to make NEURON simulation environment efficient. The computational neuroscientists divided the equations into subnets amongst multiple processors for achieving better hardware performance. On parallel machines for neuronal networks, interprocessor spikes exchange consumes large section of overall simulation time. In NEURON for communication between processors Message Passing Interface (MPI) is used. MPI_Allgather collective is exercised for spikes exchange after each interval across distributed memory systems. The increase in number of processors though results in achieving concurrency and better performance but it inversely affects MPI_Allgather which increases communication time between processors. This necessitates improving communication methodology to decrease the spikes exchange time over distributed memory systems. This work has improved MPI_Allgather method using Remote Memory Access (RMA) by moving two-sided communication to one-sided communication, and use of recursive doubling mechanism facilitates achieving efficient communication between the processors in precise steps. This approach enhanced communication concurrency and has improved overall runtime making NEURON more efficient for simulation of large neuronal network models. PMID:27413363

  20. Optimizing NEURON Simulation Environment Using Remote Memory Access with Recursive Doubling on Distributed Memory Systems

    PubMed Central

    Bozkuş, Zeki

    2016-01-01

    Increase in complexity of neuronal network models escalated the efforts to make NEURON simulation environment efficient. The computational neuroscientists divided the equations into subnets amongst multiple processors for achieving better hardware performance. On parallel machines for neuronal networks, interprocessor spikes exchange consumes large section of overall simulation time. In NEURON for communication between processors Message Passing Interface (MPI) is used. MPI_Allgather collective is exercised for spikes exchange after each interval across distributed memory systems. The increase in number of processors though results in achieving concurrency and better performance but it inversely affects MPI_Allgather which increases communication time between processors. This necessitates improving communication methodology to decrease the spikes exchange time over distributed memory systems. This work has improved MPI_Allgather method using Remote Memory Access (RMA) by moving two-sided communication to one-sided communication, and use of recursive doubling mechanism facilitates achieving efficient communication between the processors in precise steps. This approach enhanced communication concurrency and has improved overall runtime making NEURON more efficient for simulation of large neuronal network models. PMID:27413363

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Working memory capacity and retrieval limitations from long-term memory: an examination of differences in accessibility.

    PubMed

    Unsworth, Nash; Spillers, Gregory J; Brewer, Gene A

    2012-01-01

    In two experiments, the locus of individual differences in working memory capacity and long-term memory recall was examined. Participants performed categorical cued and free recall tasks, and individual differences in the dynamics of recall were interpreted in terms of a hierarchical-search framework. The results from this study are in accordance with recent theorizing suggesting a strong relation between working memory capacity and retrieval from long-term memory. Furthermore, the results also indicate that individual differences in categorical recall are partially due to differences in accessibility. In terms of accessibility of target information, two important factors drive the difference between high- and low-working-memory-capacity participants. Low-working-memory-capacity participants fail to utilize appropriate retrieval strategies to access cues, and they also have difficulty resolving cue overload. Thus, when low-working-memory-capacity participants were given specific cues that activated a smaller set of potential targets, their recall performance was the same as that of high-working-memory-capacity participants. PMID:22800472

  3. All-Metal Magnetic RAM

    NASA Technical Reports Server (NTRS)

    Torok, E. J.; Spitzer, R.

    2000-01-01

    The factors that enter into the development of an all-metal, nonvolatile magnetic RAM, in which multilayer giant magnetoresistive films are used for all functions - storage, readout, and support electronics - are described. Four significant characteristics are expected to favor all-metal over hybrid magnetic RAM. First, silicon-technology fabrication requires a large number of masking steps, including complex ones such as ion implantation. Conversely, all-metal technology is inherently simple: fewer masking steps, no doping, scaling to lithographic limits, very little operating power. Second, the all-metal footprint is significantly smaller than the hybrid one. Third, an all-metal RAM is expected to be able to be miniaturized to lithographic limits; miniaturization of hybrid magnetic RAMs is likely to be limited by the semiconductor circuitry. Finally, semiconductor processing and magnetic processing in MRAM are done separately because the former requires high temperatures, whereas magnetic fabrication is a low-temperature process. By contrast, because both GMR electronics and the memory elements are made of the same materials, the two major components are deposited and patterned concurrently on the same substrate.

  4. CMOS Interface Circuits for Spin Tunneling Junction Based Magnetic Random Access Memories

    SciTech Connect

    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.

  5. Mapping virtual addresses to different physical addresses for value disambiguation for thread memory access requests

    DOEpatents

    Gala, Alan; Ohmacht, Martin

    2014-09-02

    A multiprocessor system includes nodes. Each node includes a data path that includes a core, a TLB, and a first level cache implementing disambiguation. The system also includes at least one second level cache and a main memory. For thread memory access requests, the core uses an address associated with an instruction format of the core. The first level cache uses an address format related to the size of the main memory plus an offset corresponding to hardware thread meta data. The second level cache uses a physical main memory address plus software thread meta data to store the memory access request. The second level cache accesses the main memory using the physical address with neither the offset nor the thread meta data after resolving speculation. In short, this system includes mapping of a virtual address to a different physical addresses for value disambiguation for different threads.

  6. Viable chemical approach for patterning nanoscale magnetoresistive random access memory

    SciTech Connect

    Kim, Taeseung; Kim, Younghee; Chen, Jack Kun-Chieh; Chang, Jane P.

    2015-03-15

    A reactive ion etching process with alternating Cl{sub 2} and H{sub 2} exposures has been shown to chemically etch CoFe film that is an integral component in magnetoresistive random access memory (MRAM). Starting with systematic thermodynamic calculations assessing various chemistries and reaction pathways leading to the highest possible vapor pressure of the etch products reactions, the potential chemical combinations were verified by etch rate investigation and surface chemistry analysis in plasma treated CoFe films. An ∼20% enhancement in etch rate was observed with the alternating use of Cl{sub 2} and H{sub 2} plasmas, in comparison with the use of only Cl{sub 2} plasma. This chemical combination was effective in removing metal chloride layers, thus maintaining the desired magnetic properties of the CoFe films. Scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy showed visually and spectroscopically that the metal chloride layers generated by Cl{sub 2} plasma were eliminated with H{sub 2} plasma to yield a clean etch profile. This work suggests that the selected chemistries can be used to etch magnetic metal alloys with a smooth etch profile and this general strategy can be applied to design chemically based etch processes to enable the fabrication of highly integrated nanoscale MRAM devices.

  7. Radiation dosimetry using three-dimensional optical random access memories

    NASA Technical Reports Server (NTRS)

    Moscovitch, M.; Phillips, G. W.

    2001-01-01

    Three-dimensional optical random access memories (3D ORAMs) are a new generation of high-density data storage devices. Binary information is stored and retrieved via a light induced reversible transformation of an ensemble of bistable photochromic molecules embedded in a polymer matrix. This paper describes the application of 3D ORAM materials to radiation dosimetry. It is shown both theoretically and experimentally, that ionizing radiation in the form of heavy charged particles is capable of changing the information originally stored on the ORAM material. The magnitude and spatial distribution of these changes are used as a measure of the absorbed dose, particle type and energy. The effects of exposure on 3D ORAM materials have been investigated for a variety of particle types and energies, including protons, alpha particles and 12C ions. The exposed materials are observed to fluoresce when exposed to laser light. The intensity and the depth of the fluorescence is dependent on the type and energy of the particle to which the materials were exposed. It is shown that these effects can be modeled using Monte Carlo calculations. The model provides a better understanding of the properties of these materials. which should prove useful for developing systems for charged particle and neutron dosimetry/detector applications. c2001 Published by Elsevier Science B.V.

  8. Hugoniot analysis of the ram accelerator

    NASA Astrophysics Data System (ADS)

    Knowlen, C.; Bruckner, A. P.

    The thermodynamic properties of a combustible propellant gas, after it has been processed by a ram accelerator propulsive mode, are related by a 'ram accelerator Hugoniot' expression. These end states are determined from the 1-D conservation equations in a manner similar to that used for detonation waves, but with the addition of a force term in the momentum equation. Establishment of a region of potentially accessible thermodynamic end states that are consistent with ram accelerator operation at and above the Chapman-Jouguet detonation speed indicates that there are no fundamental constraints on accelerating projectiles over a wide range of Mach numbers in a single propellant mixture. Interpreting experimental data in the context of a generalized ram accelerator process leads to relatively simple propulsive models which can predict the projectile acceleration of any propulsive mode. The projectile velocity and acceleration histories determined by the Hugoniot analysis for the thermally choked ram accelerator mode are in excellent agreement with experiments.

  9. 32-Bit-Wide Memory Tolerates Failures

    NASA Technical Reports Server (NTRS)

    Buskirk, Glenn A.

    1990-01-01

    Electronic memory system of 32-bit words corrects bit errors caused by some common type of failures - even failure of entire 4-bit-wide random-access-memory (RAM) chip. Detects failure of two such chips, so user warned that ouput of memory may contain errors. Includes eight 4-bit-wide DRAM's configured so each bit of each DRAM assigned to different one of four parallel 8-bit words. Each DRAM contributes only 1 bit to each 8-bit word.

  10. Predicting fluctuations in widespread interest: memory decay and goal-related memory accessibility in internet search trends.

    PubMed

    Masicampo, E J; Ambady, Nalini

    2014-02-01

    Memory and interest respond in similar ways to people's shifting needs and motivations. We therefore tested whether memory and interest might produce similar, observable patterns in people's responses over time. Specifically, the present studies examined whether fluctuations in widespread interest (as measured by Internet search trends) resemble two well-established memory patterns: memory decay and goal-related memory accessibility. We examined national and international events (e.g., Nobel Prize selections, holidays) that produced spikes in widespread interest in certain people and foods. When the events that triggered widespread interest were incidental (e.g., the death of a celebrity), widespread interest conformed to memory decay patterns: It rose quickly, fell slowly according to a power function, and was higher after the event than before it. When the events that triggered widespread interest were goal related (e.g., political elections), widespread interest conformed to patterns of goal-related memory accessibility: It rose slowly, fell quickly according to a sigmoid function, and was lower after the event than before it. Fluctuations in widespread interest over time are thus similar to standard memory patterns observed at the individual level due perhaps to common mechanisms and functions. PMID:23127417

  11. Adult Age Differences in Accessing and Retrieving Information from Long-Term Memory.

    ERIC Educational Resources Information Center

    Petros, Thomas V.; And Others

    1983-01-01

    Investigated adult age differences in accessing and retrieving information from long-term memory. Results showed that older adults (N=26) were slower than younger adults (N=35) at feature extraction, lexical access, and accessing category information. The age deficit was proportionally greater when retrieval of category information was required.…

  12. Implementing a bubble memory hierarchy system

    NASA Technical Reports Server (NTRS)

    Segura, R.; Nichols, C. D.

    1979-01-01

    This paper reports on implementation of a magnetic bubble memory in a two-level hierarchial system. The hierarchy used a major-minor loop device and RAM under microprocessor control. Dynamic memory addressing, dual bus primary memory, and hardware data modification detection are incorporated in the system to minimize access time. It is the objective of the system to incorporate the advantages of bipolar memory with that of bubble domain memory to provide a smart, optimal memory system which is easy to interface and independent of user's system.

  13. In-Depth Analysis of Computer Memory Acquisition Software for Forensic Purposes.

    PubMed

    McDown, Robert J; Varol, Cihan; Carvajal, Leonardo; Chen, Lei

    2016-01-01

    The comparison studies on random access memory (RAM) acquisition tools are either limited in metrics or the selected tools were designed to be executed in older operating systems. Therefore, this study evaluates widely used seven shareware or freeware/open source RAM acquisition forensic tools that are compatible to work with the latest 64-bit Windows operating systems. These tools' user interface capabilities, platform limitations, reporting capabilities, total execution time, shared and proprietary DLLs, modified registry keys, and invoked files during processing were compared. We observed that Windows Memory Reader and Belkasoft's Live Ram Capturer leaves the least fingerprints in memory when loaded. On the other hand, ProDiscover and FTK Imager perform poor in memory usage, processing time, DLL usage, and not-wanted artifacts introduced to the system. While Belkasoft's Live Ram Capturer is the fastest to obtain an image of the memory, Pro Discover takes the longest time to do the same job. PMID:27405017

  14. Memory-based parallel data output controller

    NASA Technical Reports Server (NTRS)

    Stattel, R. J.; Niswander, J. K. (Inventor)

    1984-01-01

    A memory-based parallel data output controller employs associative memories and memory mapping to decommutate multiple channels of telemetry data. The output controller contains a random access memory (RAM) which has at least as many address locations as there are channels. A word counter addresses the RAM which provides as it outputs an encoded peripheral device number and a MSB/LSB-first flag. The encoded device number and a bit counter address a second RAM which contains START and STOP flags to pick out the required bits from the specified word number. The LSB/MSB, START and STOP flags, along with the serial input digital data go to a control block which selectively fills a shift register used to drive the parallel data output bus.

  15. Remote Memory Access Protocol Target Node Intellectual Property

    NASA Technical Reports Server (NTRS)

    Haddad, Omar

    2013-01-01

    The MagnetoSpheric Multiscale (MMS) mission had a requirement to use the Remote Memory Access Protocol (RMAP) over its SpaceWire network. At the time, no known intellectual property (IP) cores were available for purchase. Additionally, MMS preferred to implement the RMAP functionality with control over the low-level details of the design. For example, not all the RMAP standard functionality was needed, and it was desired to implement only the portions of the RMAP protocol that were needed. RMAP functionality had been previously implemented in commercial off-the-shelf (COTS) products, but the IP core was not available for purchase. The RMAP Target IP core is a VHDL (VHSIC Hardware Description Language description of a digital logic design suitable for implementation in an FPGA (field-programmable gate array) or ASIC (application-specific integrated circuit) that parses SpaceWire packets that conform to the RMAP standard. The RMAP packet protocol allows a network host to access and control a target device using address mapping. This capability allows SpaceWire devices to be managed in a standardized way that simplifies the hardware design of the device, as well as the development of the software that controls the device. The RMAP Target IP core has some features that are unique and not specified in the RMAP standard. One such feature is the ability to automatically abort transactions if the back-end logic does not respond to read/write requests within a predefined time. When a request times out, the RMAP Target IP core automatically retracts the request and returns a command response with an appropriate status in the response packet s header. Another such feature is the ability to control the SpaceWire node or router using RMAP transactions in the extended address range. This allows the SpaceWire network host to manage the SpaceWire network elements using RMAP packets, which reduces the number of protocols that the network host needs to support.

  16. RAPID: A random access picture digitizer, display, and memory system

    NASA Technical Reports Server (NTRS)

    Yakimovsky, Y.; Rayfield, M.; Eskenazi, R.

    1976-01-01

    RAPID is a system capable of providing convenient digital analysis of video data in real-time. It has two modes of operation. The first allows for continuous digitization of an EIA RS-170 video signal. Each frame in the video signal is digitized and written in 1/30 of a second into RAPID's internal memory. The second mode leaves the content of the internal memory independent of the current input video. In both modes of operation the image contained in the memory is used to generate an EIA RS-170 composite video output signal representing the digitized image in the memory so that it can be displayed on a monitor.

  17. FPS-RAM: Fast Prefix Search RAM-Based Hardware for Forwarding Engine

    NASA Astrophysics Data System (ADS)

    Zaitsu, Kazuya; Yamamoto, Koji; Kuroda, Yasuto; Inoue, Kazunari; Ata, Shingo; Oka, Ikuo

    Ternary content addressable memory (TCAM) is becoming very popular for designing high-throughput forwarding engines on routers. However, TCAM has potential problems in terms of hardware and power costs, which limits its ability to deploy large amounts of capacity in IP routers. In this paper, we propose new hardware architecture for fast forwarding engines, called fast prefix search RAM-based hardware (FPS-RAM). We designed FPS-RAM hardware with the intent of maintaining the same search performance and physical user interface as TCAM because our objective is to replace the TCAM in the market. Our RAM-based hardware architecture is completely different from that of TCAM and has dramatically reduced the costs and power consumption to 62% and 52%, respectively. We implemented FPS-RAM on an FPGA to examine its lookup operation.

  18. Development of Curie point switching for thin film, random access, memory device

    NASA Technical Reports Server (NTRS)

    Lewicki, G. W.; Tchernev, D. I.

    1967-01-01

    Managanese bismuthide films are used in the development of a random access memory device of high packing density and nondestructive readout capability. Memory entry is by Curie point switching using a laser beam. Readout is accomplished by microoptical or micromagnetic scanning.

  19. Control of Access to Memory: The Use of Task Interference as a Behavioral Probe

    ERIC Educational Resources Information Center

    Loft, Shayne; Humphreys, Michael S.; Whitney, Susannah J.

    2008-01-01

    Directed forgetting and prospective memory methods were combined to examine differences in the control of memory access. Between studying two lists of target words, participants were either instructed to forget the first list, or to continue remembering the first list. After study participants performed a lexical decision task with an additional…

  20. The structured memory access architecture: An implementation and performance-evaluation

    SciTech Connect

    Cyr, J.B.

    1986-08-01

    The Structured Memory Access (SMS) architecture implementation presented in this thesis is formulated with the intention of alleviating two well-known inefficiencies that exist in current scalar computer architectures: address generation overhead and memory bandwidth utilization. Furthermore, the SMA architecture introduces an additional level of parallelism which is not present in current pipelined supercomputers, namely, overlapped execution of the access process and execute process on two distinct special-purpose, asynchronously-coupled processors. Each processor executes a separate instruction stream to perform its specific task which, together, are functionally equivalent in a conventional program. Our simulation results show that, for typical numerical programs, the access processor (MAP) is capable of achieving slip, i.e., running sufficiently ahead of the execute processor (CP) so that operand fetch requests for data items required by the CP are issued early enough and rapidly enough for the CP rarely to experience any memory access wait time. In this manner the SMA tolerates long memory access time, albeit high bandwidth, paths to memory without sacrificing performance. Speedups relative to the Cray-1 in scalar mode often exceed two, due to dual processing and reductions in memory wait time. 17 refs., 11 figs., 3 tabs.

  1. Integration of lead zirconium titanate thin films for high density ferroelectric random access memory

    NASA Astrophysics Data System (ADS)

    Kim, Kinam; Lee, Sungyung

    2006-09-01

    Interests are being focused on types of nonvolatile memories such as ferroelectric random access memory (FRAM), phase change random access memory, or magnetoresistance random access memory due to their distinct memory properties such as excellent write performance which conventional nonvolatile memories do not possess. Among these types of nonvolatile memories, FRAM whose cell structure and operation are almost identical to dynamic random access memory (DRAM) can ideally realize cell size and speed of DRAM. Thus FRAM is the most appropriate candidate for future universal memory where all memory functions are performed with a single chip solution. Due to the poor ferroelectric properties of downscaled ultrathin lead zirconium titanate (PZT) capacitors as well as technical issues such as hydrogen and plasma related degradation arising from embedding ferroelectric metal-insulator-metal capacitors into conventional complementary metal oxide semiconductor processes, current FRAM still falls far below its ideally attainable cell size and performance. In this paper, based upon PZT capacitor, current mass-productive one pass transistor and one storage capacitor (1T1C), capacitor over bit line (COB) cell technologies are introduced upon which cell size of 0.937μm2 at 250nm minimum feature size technology node has been realized. And then, most recent 1T1C, COB cell technologies are discussed from which cell size of 0.27μm2 at 150nm minimum feature size technology node has been realized, and finally future three dimensional capacitor technologies for the FRAM with cell size of less than 0.08μm2 beyond 100nm minimum feature size technology node are suggested.

  2. Novel Pb(Ti, Zr)O3(PZT) Crystallization Technique Using Flash Lamp for Ferroelectric RAM (FeRAM) Embedded LSIs and One Transistor Type FeRAM Devices

    NASA Astrophysics Data System (ADS)

    Yamakawa, Koji; Imai, Keitaro; Arisumi, Osamu; Arikado, Tsunetoshi; Yoshioka, Masaki; Owada, Tatsushi; Okumura, Katsuya

    2002-04-01

    A novel method of ferroelectric capacitor formation for Ferroelectrie random access memory (FeRAM) embedded LSIs and one-transistor-type FeRAMs has been developed. Amorphous Pb(Ti, Zr)O3(PZT) films were successfully transformed to the perovskite phase by a flash lamp technique with a crystallization time of 1.2 ms at a substrate temperature of 350°C. A flash lamp energy of 27 J/cm2 was sufficient to form a ferroelectric crystal structure due to rapid thermal effects with little heat diffusion in the depth direction. This technique enabled PZT film crystallization in Pt/PZT/Pt structures on multi-Al wiring layers. Granular PZT grains were observed on Pt, Ru and RuO2 electrodes, which indicates that crystal growth begins from the film surfaces. Ferroelectric property was verified by the process at 350°C maximum temperature. PZT films were also crystallized directly on SiO2. This is useful for the fabrication of embedded FeRAM devices and 1Tr-type FeRAMs. The flash lamp process was found to have great potential for application to dielectric film formation, annealing processes and so on.

  3. Switching operation and degradation of resistive random access memory composed of tungsten oxide and copper investigated using in-situ TEM

    PubMed Central

    Arita, Masashi; Takahashi, Akihito; Ohno, Yuuki; Nakane, Akitoshi; Tsurumaki-Fukuchi, Atsushi; Takahashi, Yasuo

    2015-01-01

    In-situ transmission electron microscopy (in-situ TEM) was performed to investigate the switching operation of a resistive random access memory (ReRAM) made of copper, tungsten oxide and titanium nitride (Cu/WOx/TiN). In the first Set (Forming) operation to initialize the device, precipitation appeared inside the WOx layer. It was presumed that a Cu conducting filament was formed, lowering the resistance (on-state). The Reset operation induced a higher resistance (the off-state). No change in the microstructure was identified in the TEM images. Only when an additional Reset current was applied after switching to the off-state could erasure of the filament be seen (over-Reset). Therefore, it was concluded that structural change relating to the resistance switch was localized in a very small area around the filament. With repeated switching operations and increasing operational current, the WOx/electrode interfaces became indistinct. At the same time, the resistance of the off-state gradually decreased. This is thought to be caused by Cu condensation at the interfaces because of leakage current through the area other than through the filament. This will lead to device degradation through mechanisms such as endurance failure. This is the first accelerated aging test of ReRAM achieved using in-situ TEM. PMID:26611856

  4. Switching operation and degradation of resistive random access memory composed of tungsten oxide and copper investigated using in-situ TEM.

    PubMed

    Arita, Masashi; Takahashi, Akihito; Ohno, Yuuki; Nakane, Akitoshi; Tsurumaki-Fukuchi, Atsushi; Takahashi, Yasuo

    2015-01-01

    In-situ transmission electron microscopy (in-situ TEM) was performed to investigate the switching operation of a resistive random access memory (ReRAM) made of copper, tungsten oxide and titanium nitride (Cu/WOx/TiN). In the first Set (Forming) operation to initialize the device, precipitation appeared inside the WOx layer. It was presumed that a Cu conducting filament was formed, lowering the resistance (on-state). The Reset operation induced a higher resistance (the off-state). No change in the microstructure was identified in the TEM images. Only when an additional Reset current was applied after switching to the off-state could erasure of the filament be seen (over-Reset). Therefore, it was concluded that structural change relating to the resistance switch was localized in a very small area around the filament. With repeated switching operations and increasing operational current, the WOx/electrode interfaces became indistinct. At the same time, the resistance of the off-state gradually decreased. This is thought to be caused by Cu condensation at the interfaces because of leakage current through the area other than through the filament. This will lead to device degradation through mechanisms such as endurance failure. This is the first accelerated aging test of ReRAM achieved using in-situ TEM. PMID:26611856

  5. Switching operation and degradation of resistive random access memory composed of tungsten oxide and copper investigated using in-situ TEM

    NASA Astrophysics Data System (ADS)

    Arita, Masashi; Takahashi, Akihito; Ohno, Yuuki; Nakane, Akitoshi; Tsurumaki-Fukuchi, Atsushi; Takahashi, Yasuo

    2015-11-01

    In-situ transmission electron microscopy (in-situ TEM) was performed to investigate the switching operation of a resistive random access memory (ReRAM) made of copper, tungsten oxide and titanium nitride (Cu/WOx/TiN). In the first Set (Forming) operation to initialize the device, precipitation appeared inside the WOx layer. It was presumed that a Cu conducting filament was formed, lowering the resistance (on-state). The Reset operation induced a higher resistance (the off-state). No change in the microstructure was identified in the TEM images. Only when an additional Reset current was applied after switching to the off-state could erasure of the filament be seen (over-Reset). Therefore, it was concluded that structural change relating to the resistance switch was localized in a very small area around the filament. With repeated switching operations and increasing operational current, the WOx/electrode interfaces became indistinct. At the same time, the resistance of the off-state gradually decreased. This is thought to be caused by Cu condensation at the interfaces because of leakage current through the area other than through the filament. This will lead to device degradation through mechanisms such as endurance failure. This is the first accelerated aging test of ReRAM achieved using in-situ TEM.

  6. High speed magneto-resistive random access memory

    NASA Technical Reports Server (NTRS)

    Wu, Jiin-Chuan (Inventor); Stadler, Henry L. (Inventor); Katti, Romney R. (Inventor)

    1992-01-01

    A high speed read MRAM memory element is configured from a sandwich of magnetizable, ferromagnetic film surrounding a magneto-resistive film which may be ferromagnetic or not. One outer ferromagnetic film has a higher coercive force than the other and therefore remains magnetized in one sense while the other may be switched in sense by a switching magnetic field. The magneto-resistive film is therefore sensitive to the amplitude of the resultant field between the outer ferromagnetic films and may be constructed of a high resistivity, high magneto-resistive material capable of higher sensing currents. This permits higher read voltages and therefore faster read operations. Alternate embodiments with perpendicular anisotropy, and in-plane anisotropy are shown, including an embodiment which uses high permeability guides to direct the closing flux path through the magneto-resistive material. High density, high speed, radiation hard, memory matrices may be constructed from these memory elements.

  7. Dynamic Optical Gratings Accessed by Reversible Shape Memory.

    PubMed

    Tippets, Cary A; Li, Qiaoxi; Fu, Yulan; Donev, Eugenii U; Zhou, Jing; Turner, Sara A; Jackson, Anne-Martine S; Ashby, Valerie Sheares; Sheiko, Sergei S; Lopez, Rene

    2015-07-01

    Shape memory polymers (SMPs) have been shown to accurately replicate photonic structures that produce tunable optical responses, but in practice, these responses are limited by the irreversibility of conventional shape memory processes. Here, we report the intensity modulation of a diffraction grating utilizing two-way reversible shape changes. Reversible shifting of the grating height was accomplished through partial melting and recrystallization of semicrystalline poly(octylene adipate). The concurrent variations of the grating shape and diffraction intensity were monitored via atomic force microscopy and first order diffraction measurements, respectively. A maximum reversibility of the diffraction intensity of 36% was repeatable over multiple cycles. To that end, the reversible shape memory process is shown to broaden the functionality of SMP-based optical devices. PMID:26081101

  8. Hybrid Flexible Resistive Random Access Memory-Gated Transistor for Novel Nonvolatile Data Storage.

    PubMed

    Han, Su-Ting; Zhou, Ye; Chen, Bo; Wang, Chundong; Zhou, Li; Yan, Yan; Zhuang, Jiaqing; Sun, Qijun; Zhang, Hua; Roy, V A L

    2016-01-20

    Here, a single-device demonstration of novel hybrid architecture is reported to achieve programmable transistor nodes which have analogies to flash memory by incorporating a resistive switching random access memory (RRAM) device as a resistive switch gate for field effect transistor (FET) on a flexible substrate. A high performance flexible RRAM with a three-layered structure is fabricated by utilizing solution-processed MoS2 nanosheets sandwiched between poly(methyl methacrylate) polymer layers. Gate coupling with the pentacene-based transistor can be controlled by the RRAM memory state to produce a nonprogrammed state (inactive) and a programmed state (active) with a well-defined memory window. Compared to the reference flash memory device based on the MoS2 floating gate, the hybrid device presents robust access speed and retention ability. Furthermore, the hybrid RRAM-gated FET is used to build an integrated logic circuit and a wide logic window in inverter logic is achieved. The controllable, well-defined memory window, long retention time, and fast access speed of this novel hybrid device may open up new possibilities of realizing fully functional nonvolatile memory for high-performance flexible electronics. PMID:26578160

  9. Asymmetrical access to color and location in visual working memory.

    PubMed

    Rajsic, Jason; Wilson, Daryl E

    2014-10-01

    Models of visual working memory (VWM) have benefitted greatly from the use of the delayed-matching paradigm. However, in this task, the ability to recall a probed feature is confounded with the ability to maintain the proper binding between the feature that is to be reported and the feature (typically location) that is used to cue a particular item for report. Given that location is typically used as a cue-feature, we used the delayed-estimation paradigm to compare memory for location to memory for color, rotating which feature was used as a cue and which was reported. Our results revealed several novel findings: 1) the likelihood of reporting a probed object's feature was superior when reporting location with a color cue than when reporting color with a location cue; 2) location report errors were composed entirely of swap errors, with little to no random location reports; and 3) both colour and location reports greatly benefitted from the presence of nonprobed items at test. This last finding suggests that it is uncertainty over the bindings between locations and colors at memory retrieval that drive swap errors, not at encoding. We interpret our findings as consistent with a representational architecture that nests remembered object features within remembered locations. PMID:25190322

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

    NASA Astrophysics Data System (ADS)

    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

  11. DFT Calculation of Vibrational Frequencies of FeCoB m-RAM

    NASA Astrophysics Data System (ADS)

    Ling, Lee Li; Jesudason, Christopher; Shrivastava, Keshav N.

    2010-07-01

    The present available random access memory materials are semiconductors. It is proposed to develop magnetoresistance based random access memory (m-RAM) materials. Hence, we consider an alloy of Fe, Co and B which will be strongly magnetic and work well as a memory device. We calculate the vibrational frequencies of clusters of atoms of Fe, Co and B. The larger vibrational frequencies indicate larger force constants. The result show that CoB3Fe to have the largest vibrational frequency of 1293.03 cm-1 whereas BFeCo2 has 509.59 cm-1. We identify the ratio of constituents and the structures which have large force constant. Hence, CoB3Fe is better than BFeCo2. The cluster formation depends on the method of quenching. Hence, method of preparation can be modified to achieve large force constants.

  12. Ram Burn Observations (RAMBO)

    NASA Astrophysics Data System (ADS)

    2002-12-01

    Ram Burn Observations (RAMBO) is a Department of Defense experiment that observes shuttle Orbital Maneuvering System engine burns for the purpose of improving plume models. On STS-107 the appropriate sensors will observe selected rendezvous and orbit adjust burns.

  13. A graphite based STT-RAM cell with reduction in switching current

    NASA Astrophysics Data System (ADS)

    Varghani, Ali; Peiravi, Ali

    2015-10-01

    Spin Transfer Torque Random Access Memory (STT-RAM) is a serious candidate for "universal memory" because of its non-volatility, fast access time, high density, good scalability, high endurance and relatively low power dissipation. However, problems with low write speed and large write current are important existing challenges in STT-RAM design and there is a tradeoff between them and data retention time. In this study, a novel STT-RAM cell structure which uses perfect graphite based Magnetic Tunnel Junction (MTJ) is proposed. First, the cross-section of the structure is selected to be an ellipse of 45 nm and 180 nm dimensions and a six-layer graphite is used as tunnel barrier. By passing a lateral current with a short pulse width (before applying STT current and independent of it) through four middle graphene layers of the tunnel barrier, a 27% reduction in the amplitude of the switching current (for fast switching time of 2 ns) or a 58% reduction in its pulse width is achieved without any reduction in data retention time. Finally, the effect of downscaling of technology on the proposed structure is evaluated. A reduction of 31.6% and 9% in switching current is achieved for 90 and 22 nm cell width respectively by passing sufficient current (100 μA with 0.1 ns pulse width) through the tunnel barrier. Simulations are done using Object Oriented Micro Magnetic Framework (OOMMF).

  14. Optical interconnection network for parallel access to multi-rank memory in future computing systems.

    PubMed

    Wang, Kang; Gu, Huaxi; Yang, Yintang; Wang, Kun

    2015-08-10

    With the number of cores increasing, there is an emerging need for a high-bandwidth low-latency interconnection network, serving core-to-memory communication. In this paper, aiming at the goal of simultaneous access to multi-rank memory, we propose an optical interconnection network for core-to-memory communication. In the proposed network, the wavelength usage is delicately arranged so that cores can communicate with different ranks at the same time and broadcast for flow control can be achieved. A distributed memory controller architecture that works in a pipeline mode is also designed for efficient optical communication and transaction address processes. The scaling method and wavelength assignment for the proposed network are investigated. Compared with traditional electronic bus-based core-to-memory communication, the simulation results based on the PARSEC benchmark show that the bandwidth enhancement and latency reduction are apparent. PMID:26367901

  15. Spin-transfer torque magnetoresistive random-access memory technologies for normally off computing (invited)

    SciTech Connect

    Ando, K. Yuasa, S.; Fujita, S.; Ito, J.; Yoda, H.; Suzuki, Y.; Nakatani, Y.; Miyazaki, T.

    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.

  16. Ram-jet Performance

    NASA Technical Reports Server (NTRS)

    Cervenko, A. J.; Friedman, R.

    1956-01-01

    The ram jet is basically one of the most dimple types of aircraft engine. It consists only of an inlet diffuser, a combustion system, and an exit nozzle. A typical ram-jet configuration is shown in figure 128. The engine operates on the Brayton cycle, and ideal cycle efficiency depends only on the ratio of engine to ambient pressure. The increased, engine pressures are obtained by ram action alone, and for this reason the ram jet has zero thrust at zero speed. Therefore, ram-jet-powered aircraft must be boosted to flight speeds close to a Mach number of 1.0 before appreciable thrust is generated by the engine. Since pressure increases are obtained by ram action alone, combustor-inlet pressures and temperatures are controlled by the flight speed, the ambient atmospheric condition, and by the efficiency of the inlet diffuser. These pressures and temperatures, as functions of flight speed and altitude, are shown in figure 129 for the NACA standard atmosphere and for practical values of diffuser efficiency. It can be seen that very wide ranges of combustor-inlet temperatures and pressures may be encountered over the ranges of flight velocity and altitude at which ram jets may be operated. Combustor-inlet temperatures from 500 degrees to 1500 degrees R and inlet pressures from 5 to 100 pounds per square inch absolute represent the approximate ranges of interest in current combustor development work. Since the ram jet has no moving parts in the combustor outlet, higher exhaust-gas temperatures than those used in current turbojets are permissible. Therefore, fuel-air ratios equivalent to maximum rates of air specific impulse or heat release can be used, and, for hydrocarbon fuels, this weight ratio is about 0.070. Lower fuel-air ratios down to about 0.015 may also be required to permit efficient cruise operation. This fuel-air-ratio range of 0.015 to 0.070 used in ram jets can be compared with the fuel-air ratios up to 0.025 encountered in current turbojets. Ram

  17. Symmetric Data Objects and Remote Memory Access Communication for Fortran 95-Applications.

    SciTech Connect

    Nieplocha, Jarek; Baxter, Douglas J.; Tipparaju, Vinod; Rasmussen, Craig; Numrich, Robert W.

    2005-08-01

    Symmetric data objects have been introduced by Cray Inc. in context of SHMEM remote memory access communication on Cray T3D/E systems and later adopted by SGI for their Origin servers. Symmetric data objects greatly simplify parallel programming by allowing to reference remote instance of a data structure by specifying address of the local counterpart. The current paper describes how symmetric data objects and remote memory access communication could be implemented in Fortran-95 without requiring specialized hardware or compiler support. NAS Multi-Grid parallel benchmark was used as an application example and demonstrated competitive performance to the standard MPI implementation

  18. Overview of emerging nonvolatile memory technologies

    PubMed Central

    2014-01-01

    Nonvolatile memory technologies in Si-based electronics date back to the 1990s. Ferroelectric field-effect transistor (FeFET) was one of the most promising devices replacing the conventional Flash memory facing physical scaling limitations at those times. A variant of charge storage memory referred to as Flash memory is widely used in consumer electronic products such as cell phones and music players while NAND Flash-based solid-state disks (SSDs) are increasingly displacing hard disk drives as the primary storage device in laptops, desktops, and even data centers. The integration limit of Flash memories is approaching, and many new types of memory to replace conventional Flash memories have been proposed. Emerging memory technologies promise new memories to store more data at less cost than the expensive-to-build silicon chips used by popular consumer gadgets including digital cameras, cell phones and portable music players. They are being investigated and lead to the future as potential alternatives to existing memories in future computing systems. Emerging nonvolatile memory technologies such as magnetic random-access memory (MRAM), spin-transfer torque random-access memory (STT-RAM), ferroelectric random-access memory (FeRAM), phase-change memory (PCM), and resistive random-access memory (RRAM) combine the speed of static random-access memory (SRAM), the density of dynamic random-access memory (DRAM), and the nonvolatility of Flash memory and so become very attractive as another possibility for future memory hierarchies. Many other new classes of emerging memory technologies such as transparent and plastic, three-dimensional (3-D), and quantum dot memory technologies have also gained tremendous popularity in recent years. Subsequently, not an exaggeration to say that computer memory could soon earn the ultimate commercial validation for commercial scale-up and production the cheap plastic knockoff. Therefore, this review is devoted to the rapidly developing new

  19. Overview of emerging nonvolatile memory technologies.

    PubMed

    Meena, Jagan Singh; Sze, Simon Min; Chand, Umesh; Tseng, Tseung-Yuen

    2014-01-01

    Nonvolatile memory technologies in Si-based electronics date back to the 1990s. Ferroelectric field-effect transistor (FeFET) was one of the most promising devices replacing the conventional Flash memory facing physical scaling limitations at those times. A variant of charge storage memory referred to as Flash memory is widely used in consumer electronic products such as cell phones and music players while NAND Flash-based solid-state disks (SSDs) are increasingly displacing hard disk drives as the primary storage device in laptops, desktops, and even data centers. The integration limit of Flash memories is approaching, and many new types of memory to replace conventional Flash memories have been proposed. Emerging memory technologies promise new memories to store more data at less cost than the expensive-to-build silicon chips used by popular consumer gadgets including digital cameras, cell phones and portable music players. They are being investigated and lead to the future as potential alternatives to existing memories in future computing systems. Emerging nonvolatile memory technologies such as magnetic random-access memory (MRAM), spin-transfer torque random-access memory (STT-RAM), ferroelectric random-access memory (FeRAM), phase-change memory (PCM), and resistive random-access memory (RRAM) combine the speed of static random-access memory (SRAM), the density of dynamic random-access memory (DRAM), and the nonvolatility of Flash memory and so become very attractive as another possibility for future memory hierarchies. Many other new classes of emerging memory technologies such as transparent and plastic, three-dimensional (3-D), and quantum dot memory technologies have also gained tremendous popularity in recent years. Subsequently, not an exaggeration to say that computer memory could soon earn the ultimate commercial validation for commercial scale-up and production the cheap plastic knockoff. Therefore, this review is devoted to the rapidly developing new

  20. Knowledge Accessibility, Achievement Goals, and Memory Strategy Maintenance

    ERIC Educational Resources Information Center

    Escribe, Christian; Huet, Nathalie

    2005-01-01

    Background: An important aim of educational psychology is to account for the difficulties in cognitive strategy maintenance. Possible explanations may be found in developmental studies concerning the interdependence of knowledge accessibility and strategy use, and in current achievement goal models which assume that individuals with a learning…

  1. Program partitioning for NUMA multiprocessor computer systems. [Nonuniform memory access

    SciTech Connect

    Wolski, R.M.; Feo, J.T. )

    1993-11-01

    Program partitioning and scheduling are essential steps in programming non-shared-memory computer systems. Partitioning is the separation of program operations into sequential tasks, and scheduling is the assignment of tasks to processors. To be effective, automatic methods require an accurate representation of the model of computation and the target architecture. Current partitioning methods assume today's most prevalent models -- macro dataflow and a homogeneous/two-level multicomputer system. Based on communication channels, neither model represents well the emerging class of NUMA multiprocessor computer systems consisting of hierarchical read/write memories. Consequently, the partitions generated by extant methods do not execute well on these systems. In this paper, the authors extend the conventional graph representation of the macro-dataflow model to enable mapping heuristics to consider the complex communication options supported by NUMA architectures. They describe two such heuristics. Simulated execution times of program graphs show that the model and heuristics generate higher quality program mappings than current methods for NUMA architectures.

  2. Electrical Evaluation of RCA MWS5501D Random Access Memory, Volume 2, Appendix a

    NASA Technical Reports Server (NTRS)

    Klute, A.

    1979-01-01

    The electrical characterization and qualification test results are presented for the RCA MWS5001D random access memory. The tests included functional tests, AC and DC parametric tests, AC parametric worst-case pattern selection test, determination of worst-case transition for setup and hold times, and a series of schmoo plots. The address access time, address readout time, the data hold time, and the data setup time are some of the results surveyed.

  3. Making Physical Activity Accessible to Older Adults with Memory Loss: A Feasibility Study

    ERIC Educational Resources Information Center

    Logsdon, Rebecca G.; McCurry, Susan M.; Pike, Kenneth C.; Teri, Linda

    2009-01-01

    Purpose: For individuals with mild cognitive impairment (MCI), memory loss may prevent successful engagement in exercise, a key factor in preventing additional disability. The Resources and Activities for Life Long Independence (RALLI) program uses behavioral principles to make exercise more accessible for these individuals. Exercises are broken…

  4. 77 FR 26789 - Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory Controllers and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-07

    ... violation of section 337 in the infringement of certain patents. 73 FR 75131. The principal respondent was... order. 75 FR 44989-90 (July 30, 2010). The Commission also issued cease and desist orders against those... COMMISSION Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory Controllers...

  5. Evaluation of Remote Memory Access Communication on the Cray XT3

    SciTech Connect

    Kot, Andriy; Tipparaju, Vinod; Nieplocha, Jarek; Bruggencate, Monika T.; Chrisochoides, Nikos

    2007-03-26

    This paper evaluates remote memory access (RMA) communication capabilities and performance on the Cray XT3. We discuss properties of the network hardware and Portals networking software layer and corresponding implementation issues for SHMEM and ARMCI portable RMA interfaces. The performance of these interfaces is studied and compared to MPI performance

  6. 76 FR 2336 - Dynamic Random Access Memory Semiconductors From the Republic of Korea: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-13

    ...On September 14, 2010, the Department of Commerce published in the Federal Register its preliminary results of administrative review of the countervailing duty order on dynamic random access memory semiconductors from the Republic of Korea for the period January 1, 2008, through August 10, 2008. We provided interested parties with an opportunity to comment on the preliminary results. Our......

  7. Fencing direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOEpatents

    Blocksome, Michael A.; Mamidala, Amith R.

    2013-09-03

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to segments of shared random access memory through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and a segment of shared memory; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  8. Fencing direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOEpatents

    Blocksome, Michael A; Mamidala, Amith R

    2014-02-11

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to segments of shared random access memory through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and a segment of shared memory; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  9. 75 FR 20564 - Dynamic Random Access Memory Semiconductors from the Republic of Korea: Extension of Time Limit...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-20

    ... Antidumping and Countervailing Duty Administrative Reviews and Requests for Revocation in Part, 74 FR 48224... International Trade Administration Dynamic Random Access Memory Semiconductors from the Republic of Korea... administrative review of the countervailing duty order on dynamic random access memory semiconductors from...

  10. 75 FR 44283 - In the Matter of Certain Dynamic Random Access Memory Semiconductors and Products Containing Same...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-28

    ... America Corp. of Milpitas, California (collectively ``complainants''). 75 FR 14467-68 (March 25, 2010... COMMISSION In the Matter of Certain Dynamic Random Access Memory Semiconductors and Products Containing Same... within the United States after importation of certain dynamic random access memory semiconductors...

  11. Shared direct memory access on the Explorer 2-LX

    NASA Technical Reports Server (NTRS)

    Musgrave, Jeffrey L.

    1990-01-01

    Advances in Expert System technology and Artificial Intelligence have provided a framework for applying automated Intelligence to the solution of problems which were generally perceived as intractable using more classical approaches. As a result, hybrid architectures and parallel processing capability have become more common in computing environments. The Texas Instruments Explorer II-LX is an example of a machine which combines a symbolic processing environment, and a computationally oriented environment in a single chassis for integrated problem solutions. This user's manual is an attempt to make these capabilities more accessible to a wider range of engineers and programmers with problems well suited to solution in such an environment.

  12. Advanced Cu chemical displacement technique for SiO2-based electrochemical metallization ReRAM application.

    PubMed

    Chin, Fun-Tat; Lin, Yu-Hsien; You, Hsin-Chiang; Yang, Wen-Luh; Lin, Li-Min; Hsiao, Yu-Ping; Ko, Chum-Min; Chao, Tien-Sheng

    2014-01-01

    This study investigates an advanced copper (Cu) chemical displacement technique (CDT) with varying the chemical displacement time for fabricating Cu/SiO2-stacked resistive random-access memory (ReRAM). Compared with other Cu deposition methods, this CDT easily controls the interface of the Cu-insulator, the switching layer thickness, and the immunity of the Cu etching process, assisting the 1-transistor-1-ReRAM (1T-1R) structure and system-on-chip integration. The modulated shape of the Cu-SiO2 interface and the thickness of the SiO2 layer obtained by CDT-based Cu deposition on SiO2 were confirmed by scanning electron microscopy and atomic force microscopy. The CDT-fabricated Cu/SiO2-stacked ReRAM exhibited lower operation voltages and more stable data retention characteristics than the control Cu/SiO2-stacked sample. As the Cu CDT processing time increased, the forming and set voltages of the CDT-fabricated Cu/SiO2-stacked ReRAM decreased. Conversely, decreasing the processing time reduced the on-state current and reset voltage while increasing the endurance switching cycle time. Therefore, the switching characteristics were easily modulated by Cu CDT, yielding a high performance electrochemical metallization (ECM)-type ReRAM. PMID:25364318

  13. The Ram's Horn.

    ERIC Educational Resources Information Center

    Rassias, John A., Ed.; And Others

    1983-01-01

    The summer-fall and winter-spring numbers of the journal, "The Ram's Horn," contain these articles: "The Text as Dramatic Departure"; "The Dartmouth Language Outreach Approach to Spanish for Police Action"; "The Dartmouth Intensive Language Model (DILM) in Florida: John Rassias with High School Teachers"; "The Flexibility of Using Drama Techniques…

  14. Annealing Effect of Al2O3 Tunnel Barriers in HfO2-Based ReRAM Devices on Nonlinear Resistive Switching Characteristics.

    PubMed

    Park, Sukhyung; Cho, Kyoungah; Jung, Jungwoo; Kim, Sangsig

    2015-10-01

    In this study, we demonstrate the enhancement of the nonlinear resistive switching characteristics of HfO2-based resistive random access memory (ReRAM) devices by carrying out thermal annealing of Al2O3 tunnel barriers. The nonlinearity of ReRAM device with an annealed Al2O3 tunnel barrier is determined to be 10.1, which is larger than that of the ReRAM device with an as-deposited Al2O3 tunnel barrier. From the electrical characteristics of the ReRAM devices with as-deposited and annealed Al2O3 tunnel barriers, it reveals that there is a trade-off relationship between nonlinearity in low-resistance state (LRS) current and the ratio of the high-resistance state (HRS) and the LRS. The enhancement of nonlinearity is attributed to a change in the conduction mechanism in the LRS of the ReRAM after the annealing. While the conduction mechanism before the annealing follows Ohmic conduction, the conduction of the ReRAM after the annealing is controlled by a trap-controlled space charge limited conduction mechanism. Additionally, the annealing of the Al2O3 tunnel barriers is also shown to improve the endurance and retention characteristics. PMID:26726373

  15. Memory-based frame synchronizer. [for digital communication systems

    NASA Technical Reports Server (NTRS)

    Stattel, R. J.; Niswander, J. K. (Inventor)

    1981-01-01

    A frame synchronizer for use in digital communications systems wherein data formats can be easily and dynamically changed is described. The use of memory array elements provide increased flexibility in format selection and sync word selection in addition to real time reconfiguration ability. The frame synchronizer comprises a serial-to-parallel converter which converts a serial input data stream to a constantly changing parallel data output. This parallel data output is supplied to programmable sync word recognizers each consisting of a multiplexer and a random access memory (RAM). The multiplexer is connected to both the parallel data output and an address bus which may be connected to a microprocessor or computer for purposes of programming the sync word recognizer. The RAM is used as an associative memory or decorder and is programmed to identify a specific sync word. Additional programmable RAMs are used as counter decoders to define word bit length, frame word length, and paragraph frame length.

  16. Optical Shared Memory Computing and Multiple Access Protocols for Photonic Networks

    NASA Astrophysics Data System (ADS)

    Li, Kuang-Yu.

    In this research we investigate potential applications of optics in massively parallel computer systems, especially focusing on design issues in three-dimensional optical data storage and free-space photonic networks. An optical implementation of a shared memory uses a single photorefractive crystal and can realize the set of memory modules in a digital shared memory computer. A complete instruction set consists of R sc EAD, W sc RITE, S sc ELECTIVE E sc RASE, and R sc EFRESH, which can be applied to any memory module independent of (and in parallel with) instructions to the other memory modules. In addition, a memory module can execute a sequence of R sc EAD operations simultaneously with the execution of a W sc RITE operation to accommodate differences in optical recording and readout times common to optical volume storage media. An experimental shared memory system is demonstrated and its projected performance is analyzed. A multiplexing technique is presented to significantly reduce both grating- and beam-degeneracy crosstalk in volume holographic systems, by incorporating space, angle, and wavelength as the multiplexing parameters. In this approach, each hologram, which results from the interference between a single input node and an object array, partially overlaps with the other holograms in its neighborhood. This technique can offer improved interconnection density, optical throughput, signal fidelity, and space-bandwidth product utilization. Design principles and numerical simulation results are presented. A free-space photonic cellular hypercube parallel computer, with emphasis on the design of a collisionless multiple access protocol, is presented. This design incorporates wavelength-, space-, and time-multiplexing to achieve multiple access, wavelength reuse, dense connectivity, collisionless communications, and a simple control mechanism. Analytic models based on semi-Markov processes are employed to analyze this protocol. The performance of the

  17. Effects of erbium doping of indium tin oxide electrode in resistive random access memory

    NASA Astrophysics Data System (ADS)

    Chen, Po-Hsun; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Pan, Chih-Hung; Lin, Chih-Yang; Jin, Fu-Yuan; Chen, Min-Chen; Huang, Hui-Chun; Lo, Ikai; Zheng, Jin-Cheng; Sze, Simon M.

    2016-03-01

    Identical insulators and bottom electrodes were fabricated and capped by an indium tin oxide (ITO) film, either undoped or doped with erbium (Er), as a top electrode. This distinctive top electrode dramatically altered the resistive random access memory (RRAM) characteristics, for example, lowering the operation current and enlarging the memory window. In addition, the RESET voltage increased, whereas the SET voltage remained almost the same. A conduction model of Er-doped ITO is proposed through current-voltage (I-V) measurement and current fitting to explain the resistance switching mechanism of Er-doped ITO RRAM and is confirmed by material analysis and reliability tests.

  18. A new laterally conductive bridge random access memory by fully CMOS logic compatible process

    NASA Astrophysics Data System (ADS)

    Hsieh, Min-Che; Chin, Yung-Wen; Lin, Yu-Cheng; Chih, Yu-Der; Tsai, Kan-Hsueh; Tsai, Ming-Jinn; King, Ya-Chin; Lin, Chrong Jung

    2014-01-01

    This paper proposes a novel laterally conductive bridge random access memory (L-CBRAM) module using a fully CMOS logic compatible process. A contact buffer layer between the poly-Si and contact plug enables the lateral Ti-based atomic layer to provide on/off resistance ratio via bipolar operations. The proposed device reached more than 100 pulse cycles with an on/off ratio over 10 and very stable data retention under high temperature operations. These results make this Ti-based L-CBRAM cell a promising solution for advanced embedded multi-time programmable (MTP) memory applications.

  19. Large Capacity of Conscious Access for Incidental Memories in Natural Scenes.

    PubMed

    Kaunitz, Lisandro N; Rowe, Elise G; Tsuchiya, Naotsugu

    2016-09-01

    When searching a crowd, people can detect a target face only by direct fixation and attention. Once the target is found, it is consciously experienced and remembered, but what is the perceptual fate of the fixated nontarget faces? Whereas introspection suggests that one may remember nontargets, previous studies have proposed that almost no memory should be retained. Using a gaze-contingent paradigm, we asked subjects to visually search for a target face within a crowded natural scene and then tested their memory for nontarget faces, as well as their confidence in those memories. Subjects remembered up to seven fixated, nontarget faces with more than 70% accuracy. Memory accuracy was correlated with trial-by-trial confidence ratings, which implies that the memory was consciously maintained and accessed. When the search scene was inverted, no more than three nontarget faces were remembered. These findings imply that incidental memory for faces, such as those recalled by eyewitnesses, is more reliable than is usually assumed. PMID:27507869

  20. Pattern imprinting in deep sub-micron static random access memories induced by total dose irradiation

    NASA Astrophysics Data System (ADS)

    Zheng, Qi-Wen; Yu, Xue-Feng; Cui, Jiang-Wei; Guo, Qi; Ren, Di-Yuan; Cong, Zhong-Chao; Zhou, Hang

    2014-10-01

    Pattern imprinting in deep sub-micron static random access memories (SRAMs) during total dose irradiation is investigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell's static noise margin (SNM) and the background data, and study the influence of irradiation on the probability density function of ΔSNM, which is the difference between two data sides' SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation (STI) oxide rather than from the gate oxide of the micron-device.

  1. Design of Unstructured Adaptive (UA) NAS Parallel Benchmark Featuring Irregular, Dynamic Memory Accesses

    NASA Technical Reports Server (NTRS)

    Feng, Hui-Yu; VanderWijngaart, Rob; Biswas, Rupak; Biegel, Bryan (Technical Monitor)

    2001-01-01

    We describe the design of a new method for the measurement of the performance of modern computer systems when solving scientific problems featuring irregular, dynamic memory accesses. The method involves the solution of a stylized heat transfer problem on an unstructured, adaptive grid. A Spectral Element Method (SEM) with an adaptive, nonconforming mesh is selected to discretize the transport equation. The relatively high order of the SEM lowers the fraction of wall clock time spent on inter-processor communication, which eases the load balancing task and allows us to concentrate on the memory accesses. The benchmark is designed to be three-dimensional. Parallelization and load balance issues of a reference implementation will be described in detail in future reports.

  2. Dramatic reduction of read disturb through pulse width control in spin torque random access memory

    NASA Astrophysics Data System (ADS)

    Wang, Zihui; Wang, Xiaobin; Gan, Huadong; Jung, Dongha; Satoh, Kimihiro; Lin, Tsann; Zhou, Yuchen; Zhang, Jing; Huai, Yiming; Chang, Yao-Jen; Wu, Te-ho

    2013-09-01

    Magnetizations dynamic effect in low current read disturb region is studied both experimentally and theoretically. Dramatic read error rate reduction through read pulse width control is theoretically predicted and experimentally observed. The strong dependence of read error rate upon pulse width contrasts conventional energy barrier approach and can only be obtained considering detailed magnetization dynamics at long time thermal magnetization reversal region. Our study provides a design possibility for ultra-fast low current spin torque random access memory.

  3. Electrical Evaluation of RCA MWS5001D Random Access Memory, Volume 5, Appendix D

    NASA Technical Reports Server (NTRS)

    Klute, A.

    1979-01-01

    The electrical characterization and qualification test results are presented for the RCA MWS 5001D random access memory. The tests included functional tests, AC and DC parametric tests, AC parametric worst-case pattern selection test, determination of worst-case transition for setup and hold times, and a series of schmoo plots. Average input high current, worst case input high current, output low current, and data setup time are some of the results presented.

  4. Electrical Evaluation of RCA MWS5001D Random Access Memory, Volume 4, Appendix C

    NASA Technical Reports Server (NTRS)

    Klute, A.

    1979-01-01

    The electrical characterization and qualification test results are presented for the RCA MWS5001D random access memory. The tests included functional tests, AC and DC parametric tests, AC parametric worst-case pattern selection test, determination of worst-case transition for setup and hold times, and a series of schmoo plots. Statistical analysis data is supplied along with write pulse width, read cycle time, write cycle time, and chip enable time data.

  5. Immigration, language proficiency, and autobiographical memories: Lifespan distribution and second-language access.

    PubMed

    Esposito, Alena G; Baker-Ward, Lynne

    2016-08-01

    This investigation examined two controversies in the autobiographical literature: how cross-language immigration affects the distribution of autobiographical memories across the lifespan and under what circumstances language-dependent recall is observed. Both Spanish/English bilingual immigrants and English monolingual non-immigrants participated in a cue word study, with the bilingual sample taking part in a within-subject language manipulation. The expected bump in the number of memories from early life was observed for non-immigrants but not immigrants, who reported more memories for events surrounding immigration. Aspects of the methodology addressed possible reasons for past discrepant findings. Language-dependent recall was influenced by second-language proficiency. Results were interpreted as evidence that bilinguals with high second-language proficiency, in contrast to those with lower second-language proficiency, access a single conceptual store through either language. The final multi-level model predicting language-dependent recall, including second-language proficiency, age of immigration, internal language, and cue word language, explained ¾ of the between-person variance and (1)/5 of the within-person variance. We arrive at two conclusions. First, major life transitions influence the distribution of memories. Second, concept representation across multiple languages follows a developmental model. In addition, the results underscore the importance of considering language experience in research involving memory reports. PMID:26274061

  6. Origin of the OFF state variability in ReRAM cells

    NASA Astrophysics Data System (ADS)

    Salaoru, Iulia; Khiat, Ali; Li, Qingjiang; Berdan, Radu; Papavassiliou, Christos; Prodromakis, Themistoklis

    2014-04-01

    This work exploits the switching dynamics of nanoscale resistive random access memory (ReRAM) cells with particular emphasis on the origin of the observed variability when cells are consecutively cycled/programmed at distinct memory states. It is demonstrated that this variance is a common feature of all ReRAM elements and is ascribed to the formation and rupture of conductive filaments that expand across the active core, independently of the material employed as the active switching core, the causal physical switching mechanism, the switching mode (bipolar/unipolar) or even the unit cells' dimensions. Our hypothesis is supported through both experimental and theoretical studies on TiO2 and In2O3 : SnO2 (ITO) based ReRAM cells programmed at three distinct resistive states. Our prototypes employed TiO2 or ITO active cores over 5 × 5 µm2 and 100 × 100 µm2 cell areas, with all tested devices demonstrating both unipolar and bipolar switching modalities. In the case of TiO2-based cells, the underlying switching mechanism is based on the non-uniform displacement of ionic species that foster the formation of conductive filaments. On the other hand, the resistive switching observed in the ITO-based devices is considered to be due to a phase change mechanism. The selected experimental parameters allowed us to demonstrate that the observed programming variance is a common feature of all ReRAM devices, proving that its origin is dependent upon randomly oriented local disorders within the active core that have a substantial impact on the overall state variance, particularly for high-resistive states.

  7. Ge2Sb2Te5 Confined Structures and Integration of 64 Mb Phase-Change Random Access Memory

    NASA Astrophysics Data System (ADS)

    Yeung, Fai; Ahn, Su-Jin; Hwang, Young-Nam; Jeong, Chang-Wook; Song, Yoon-Jong; Lee, Su-Youn; Lee, Se-Ho; Ryoo, Kyung-Chang; Park, Jae-Hyun; Shin, Jae-Min; Jeong, Won-Cheol; Kim, Young-Tae; Koh, Gwan-Hyeob; Jeong, Gi-Tae; Jeong, Hong-Sik; Kim, Kinam

    2005-04-01

    Phase-change random access memory is considered a potential challenger for conventional memories, such as dynamic random access memory and flash memory due to its numerous advantages. Nevertheless, high reset current is the ultimate problem in developing high-density phase-change random access memory (PRAM). We focus on the adoption of Ge2Sb2Te5 confined structures to achieve lower reset currents. By changing from a normal to a GST confined structure, the reset current drops to as low as 0.8 mA. Eventually, our integrated 64 Mb PRAM based on 0.18 μm CMOS technology offers a large sensing margin: Rreset ˜200 kΩ and Rset ˜2 kΩ, as well as reasonable reliability: an endurance of 1.0× 109 cycles and a retention time of 2 years at 85°C.

  8. Sparse distributed memory: Principles and operation

    NASA Technical Reports Server (NTRS)

    Flynn, M. J.; Kanerva, P.; Bhadkamkar, N.

    1989-01-01

    Sparse distributed memory is a generalized random access memory (RAM) for long (1000 bit) binary words. Such words can be written into and read from the memory, and they can also be used to address the memory. The main attribute of the memory is sensitivity to similarity, meaning that a word can be read back not only by giving the original write address but also by giving one close to it as measured by the Hamming distance between addresses. Large memories of this kind are expected to have wide use in speech recognition and scene analysis, in signal detection and verification, and in adaptive control of automated equipment, in general, in dealing with real world information in real time. The memory can be realized as a simple, massively parallel computer. Digital technology has reached a point where building large memories is becoming practical. Major design issues were resolved which were faced in building the memories. The design is described of a prototype memory with 256 bit addresses and from 8 to 128 K locations for 256 bit words. A key aspect of the design is extensive use of dynamic RAM and other standard components.

  9. Sparse distributed memory prototype: Principles of operation

    NASA Technical Reports Server (NTRS)

    Flynn, Michael J.; Kanerva, Pentti; Ahanin, Bahram; Bhadkamkar, Neal; Flaherty, Paul; Hickey, Philip

    1988-01-01

    Sparse distributed memory is a generalized random access memory (RAM) for long binary words. Such words can be written into and read from the memory, and they can be used to address the memory. The main attribute of the memory is sensitivity to similarity, meaning that a word can be read back not only by giving the original right address but also by giving one close to it as measured by the Hamming distance between addresses. Large memories of this kind are expected to have wide use in speech and scene analysis, in signal detection and verification, and in adaptive control of automated equipment. The memory can be realized as a simple, massively parallel computer. Digital technology has reached a point where building large memories is becoming practical. The research is aimed at resolving major design issues that have to be faced in building the memories. The design of a prototype memory with 256-bit addresses and from 8K to 128K locations for 256-bit words is described. A key aspect of the design is extensive use of dynamic RAM and other standard components.

  10. Comprehension of Linguistic Dependencies: Speed-Accuracy Tradeoff Evidence for Direct-Access Retrieval From Memory

    PubMed Central

    Foraker, Stephani; McElree, Brian

    2012-01-01

    Comprehenders can rapidly and efficiently interpret expressions with various types of non-adjacent dependencies. In the sentence The boy that the teacher warned fell, boy is readily interpreted as the subject of the verb fall despite the fact that a relative clause, that the teacher warned, intervenes between the two dependent elements. We review research investigating three memory operations proposed for resolving this and other types of non-adjacent dependencies: serial search retrieval, in which the dependent constituent is recovered by a search process through representations in memory, direct-access retrieval in which the dependent constituent is recovered directly by retrieval cue operations without search, and active maintenance of the dependent constituent in focal attention. Studies using speed-accuracy tradeoff methodology to examine the full timecourse of interpreting a wide range of non-adjacent dependencies indicate that comprehenders retrieve dependent constituents with a direct-access operation, consistent with the claim that representations formed during comprehension are accessed with a cue-driven, content-addressable retrieval process. The observed timecourse profiles are inconsistent with a broad class of models based on several search operations for retrieval. The profiles are also inconsistent with active maintenance of a constituent while concurrently processing subsequent material, and suggest that, with few exceptions, direct-access retrieval is required to process non-adjacent dependencies. PMID:22448181

  11. Daily Access to Sucrose Impairs Aspects of Spatial Memory Tasks Reliant on Pattern Separation and Neural Proliferation in Rats

    ERIC Educational Resources Information Center

    Reichelt, Amy C.; Morris, Margaret J.; Westbrook, Reginald Frederick

    2016-01-01

    High sugar diets reduce hippocampal neurogenesis, which is required for minimizing interference between memories, a process that involves "pattern separation." We provided rats with 2 h daily access to a sucrose solution for 28 d and assessed their performance on a spatial memory task. Sucrose consuming rats discriminated between objects…

  12. Encoding and Retrieval Processes Involved in the Access of Source Information in the Absence of Item Memory

    ERIC Educational Resources Information Center

    Ball, B. Hunter; DeWitt, Michael R.; Knight, Justin B.; Hicks, Jason L.

    2014-01-01

    The current study sought to examine the relative contributions of encoding and retrieval processes in accessing contextual information in the absence of item memory using an extralist cuing procedure in which the retrieval cues used to query memory for contextual information were "related" to the target item but never actually studied.…

  13. Interleaved synchronous bus access protocol for a shared memory multi-processor system

    SciTech Connect

    Moore, W.T.

    1989-01-10

    A method is described for providing asynchronous processors with inter-processor communication and access to several memory modules over a common bus which includes a first bus and a second bus, comprising: providing clock pulses on the common bus, each pulse having a period; asserting a request signal and placing priority signal on the common bus; polling the processors during the first period to determine whether the processors request access to the common bus and to determine which one processor has priority; sending a destination address from the one processor to a destination during a second period, the destination being chosen from the processors and the several memory modules; performing one of reading input data between the destination and the processor; multiplexing priority and reading input data signals on the first bus, and multiplexing address and writing output data signals on the second bus; generating poll inhibit signals prior to each reading input data signal and prior to each memory address signal preceding a writing output data operation; and queuing the input data in a first-in-first-out manner for each of the processors when the input data indicates an interprocessor interrupt.

  14. Low-power resistive random access memory by confining the formation of conducting filaments

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Jen; Shen, Tzu-Hsien; Lee, Lan-Hsuan; Wen, Cheng-Yen; Lee, Si-Chen

    2016-06-01

    Owing to their small physical size and low power consumption, resistive random access memory (RRAM) devices are potential for future memory and logic applications in microelectronics. In this study, a new resistive switching material structure, TiOx/silver nanoparticles/TiOx/AlTiOx, fabricated between the fluorine-doped tin oxide bottom electrode and the indium tin oxide top electrode is demonstrated. The device exhibits excellent memory performances, such as low operation voltage (<±1 V), low operation power, small variation in resistance, reliable data retention, and a large memory window. The current-voltage measurement shows that the conducting mechanism in the device at the high resistance state is via electron hopping between oxygen vacancies in the resistive switching material. When the device is switched to the low resistance state, conducting filaments are formed in the resistive switching material as a result of accumulation of oxygen vacancies. The bottom AlTiOx layer in the device structure limits the formation of conducting filaments; therefore, the current and power consumption of device operation are significantly reduced.

  15. Sustained Resistive Switching in a Single Cu:7,7,8,8-tetracyanoquinodimethane Nanowire: A Promising Material for Resistive Random Access Memory

    NASA Astrophysics Data System (ADS)

    Basori, Rabaya; Kumar, Manoranjan; Raychaudhuri, Arup K.

    2016-06-01

    We report a new type of sustained and reversible unipolar resistive switching in a nanowire device made from a single strand of Cu:7,7,8,8-tetracyanoquinodimethane (Cu:TCNQ) nanowire (diameter <100 nm) that shows high ON/OFF ratio (~103), low threshold voltage of switching (~3.5 V) and large cycling endurance (>103). This indicates a promising material for high density resistive random access memory (ReRAM) device integration. Switching is observed in Cu:TCNQ single nanowire devices with two different electrode configuration: symmetric (C-Pt/Cu:TCNQ/C-Pt) and asymmetric (Cu/Cu:TCNQ/C-Pt), where contacts connecting the nanowire play an important role. This report also developed a method of separating out the electrode and material contributions in switching using metal-semiconductor-metal (MSM) device model along with a direct 4-probe resistivity measurement of the nanowire in the OFF as well as ON state. The device model was followed by a phenomenological model of current transport through the nanowire device which shows that lowering of potential barrier at the contacts likely occur due to formation of Cu filaments in the interface between nanowire and contact electrodes. We obtain quantitative agreement of numerically analyzed results with the experimental switching data.

  16. Sustained Resistive Switching in a Single Cu:7,7,8,8-tetracyanoquinodimethane Nanowire: A Promising Material for Resistive Random Access Memory.

    PubMed

    Basori, Rabaya; Kumar, Manoranjan; Raychaudhuri, Arup K

    2016-01-01

    We report a new type of sustained and reversible unipolar resistive switching in a nanowire device made from a single strand of Cu:7,7,8,8-tetracyanoquinodimethane (Cu:TCNQ) nanowire (diameter <100 nm) that shows high ON/OFF ratio (~10(3)), low threshold voltage of switching (~3.5 V) and large cycling endurance (>10(3)). This indicates a promising material for high density resistive random access memory (ReRAM) device integration. Switching is observed in Cu:TCNQ single nanowire devices with two different electrode configuration: symmetric (C-Pt/Cu:TCNQ/C-Pt) and asymmetric (Cu/Cu:TCNQ/C-Pt), where contacts connecting the nanowire play an important role. This report also developed a method of separating out the electrode and material contributions in switching using metal-semiconductor-metal (MSM) device model along with a direct 4-probe resistivity measurement of the nanowire in the OFF as well as ON state. The device model was followed by a phenomenological model of current transport through the nanowire device which shows that lowering of potential barrier at the contacts likely occur due to formation of Cu filaments in the interface between nanowire and contact electrodes. We obtain quantitative agreement of numerically analyzed results with the experimental switching data. PMID:27245099

  17. Sustained Resistive Switching in a Single Cu:7,7,8,8-tetracyanoquinodimethane Nanowire: A Promising Material for Resistive Random Access Memory

    PubMed Central

    Basori, Rabaya; Kumar, Manoranjan; Raychaudhuri, Arup K.

    2016-01-01

    We report a new type of sustained and reversible unipolar resistive switching in a nanowire device made from a single strand of Cu:7,7,8,8-tetracyanoquinodimethane (Cu:TCNQ) nanowire (diameter <100 nm) that shows high ON/OFF ratio (~103), low threshold voltage of switching (~3.5 V) and large cycling endurance (>103). This indicates a promising material for high density resistive random access memory (ReRAM) device integration. Switching is observed in Cu:TCNQ single nanowire devices with two different electrode configuration: symmetric (C-Pt/Cu:TCNQ/C-Pt) and asymmetric (Cu/Cu:TCNQ/C-Pt), where contacts connecting the nanowire play an important role. This report also developed a method of separating out the electrode and material contributions in switching using metal-semiconductor-metal (MSM) device model along with a direct 4-probe resistivity measurement of the nanowire in the OFF as well as ON state. The device model was followed by a phenomenological model of current transport through the nanowire device which shows that lowering of potential barrier at the contacts likely occur due to formation of Cu filaments in the interface between nanowire and contact electrodes. We obtain quantitative agreement of numerically analyzed results with the experimental switching data. PMID:27245099

  18. Memristor memory element based on ZnO thin film structures

    NASA Astrophysics Data System (ADS)

    Poghosyan, A. R.; Elbakyan, E. Y.; Guo, R.; Hovsepyan, R. K.

    2015-08-01

    The memristor element for random access memory (resistance random access memory - ReRAM) was developed and investigated. The developed structure consists of a Schottky diode (1D) based on Pt/ZnO:Ga/ZnO/Pt heterostructure and a memristor (1R) based on Pt/ZnO:Ga/ZnO/ZnO:Li/Pt heterostructure. Thus the unipolar memristor memory element of 1D1R type was obtained. The heterostructures were produced by the electron-beam vacuum deposition method. The laboratory samples of the memory elements were prepared and their characteristics were studied. The proposed device has a high stability and withstands 1000 switching cycles without derating.

  19. Ratioless full-complementary 12-transistor static random access memory for ultra low supply voltage operation

    NASA Astrophysics Data System (ADS)

    Kondo, Takahiro; Yamamoto, Hiromasa; Hoketsu, Satoko; Imi, Hitoshi; Okamura, Hitoshi; Nakamura, Kazuyuki

    2015-04-01

    In this study, a ratioless full-complementary 12-transistor static random access memory (SRAM) was developed and measured to evaluate its operation under an ultra low supply voltage range. The ratioless SRAM design concept enables a memory cell design that is free from the consideration of the static noise margin (SNM). Furthermore, it enables a SRAM function without the restriction of transistor parameter (W/L) settings and the dependence on the variability of device characteristics. The test chips that include both conventional 6-transistor SRAM cells and the ratioless full-complementary 12-transistor SRAM cells were developed by a 180 nm CMOS process to compare their stable operations under an ultralow supply voltage condition. The measured results show that the ratioless full-complementary 12-transistor SRAM has superior immunity to device variability, and its inherent operating ability at the supply voltage of 0.22 V was experimentally confirmed.

  20. High-density magnetoresistive random access memory operating at ultralow voltage at room temperature

    PubMed Central

    Hu, Jia-Mian; Li, Zheng; Chen, Long-Qing; Nan, Ce-Wen

    2011-01-01

    The main bottlenecks limiting the practical applications of current magnetoresistive random access memory (MRAM) technology are its low storage density and high writing energy consumption. Although a number of proposals have been reported for voltage-controlled memory device in recent years, none of them simultaneously satisfy the important device attributes: high storage capacity, low power consumption and room temperature operation. Here we present, using phase-field simulations, a simple and new pathway towards high-performance MRAMs that display significant improvements over existing MRAM technologies or proposed concepts. The proposed nanoscale MRAM device simultaneously exhibits ultrahigh storage capacity of up to 88 Gb inch−2, ultralow power dissipation as low as 0.16 fJ per bit and room temperature high-speed operation below 10 ns. PMID:22109527

  1. Self-assembled tin dioxide for forming-free resistive random-access memory application

    NASA Astrophysics Data System (ADS)

    Hong, Ying-Jhan; Wang, Tsang-Hsuan; Wei, Shih-Yuan; Chang, Pin; Yew, Tri-Rung

    2016-06-01

    A novel resistive switching structure, tin-doped indium oxide (ITO)/SnO2‑ x (defined as SnO2 with oxygen vacancies)/SnS was demonstrated with a set voltage of 0.38 V, a reset voltage of ‑0.15 V, a ratio of high resistance to low resistance of 544, and forming-free and nonlinear current–voltage (I–V) characteristics. The interface of the ITO and the self-assembled SnO2‑ x contributed to the resistive switching behavior. This device showed great potential for resistive random access memory (RRAM) application and solving the sneak path problem in cross-bar memory arrays. Furthermore, a nanostructured resistive switching device was demonstrated successfully.

  2. Non-volatile, high density, high speed, Micromagnet-Hall effect Random Access Memory (MHRAM)

    NASA Technical Reports Server (NTRS)

    Wu, Jiin C.; Katti, Romney R.; Stadler, Henry L.

    1991-01-01

    The micromagnetic Hall effect random access memory (MHRAM) has the potential of replacing ROMs, EPROMs, EEPROMs, and SRAMs because of its ability to achieve non-volatility, radiation hardness, high density, and fast access times, simultaneously. Information is stored magnetically in small magnetic elements (micromagnets), allowing unlimited data retention time, unlimited numbers of rewrite cycles, and inherent radiation hardness and SEU immunity, making the MHRAM suitable for ground based as well as spaceflight applications. The MHRAM device design is not affected by areal property fluctuations in the micromagnet, so high operating margins and high yield can be achieved in large scale integrated circuit (IC) fabrication. The MHRAM has short access times (less than 100 nsec). Write access time is short because on-chip transistors are used to gate current quickly, and magnetization reversal in the micromagnet can occur in a matter of a few nanoseconds. Read access time is short because the high electron mobility sensor (InAs or InSb) produces a large signal voltage in response to the fringing magnetic field from the micromagnet. High storage density is achieved since a unit cell consists only of two transistors and one micromagnet Hall effect element. By comparison, a DRAM unit cell has one transistor and one capacitor, and a SRAM unit cell has six transistors.

  3. Hydrogen induced redox mechanism in amorphous carbon resistive random access memory

    PubMed Central

    2014-01-01

    We investigated the bipolar resistive switching characteristics of the resistive random access memory (RRAM) device with amorphous carbon layer. Applying a forming voltage, the amorphous carbon layer was carbonized to form a conjugation double bond conductive filament. We proposed a hydrogen redox model to clarify the resistive switch mechanism of high/low resistance states (HRS/LRS) in carbon RRAM. The electrical conduction mechanism of LRS is attributed to conductive sp2 carbon filament with conjugation double bonds by dehydrogenation, while the electrical conduction of HRS resulted from the formation of insulating sp3-type carbon filament through hydrogenation process. PMID:24475979

  4. A stochastic simulation method for the assessment of resistive random access memory retention reliability

    SciTech Connect

    Berco, Dan Tseng, Tseung-Yuen

    2015-12-21

    This study presents an evaluation method for resistive random access memory retention reliability based on the Metropolis Monte Carlo algorithm and Gibbs free energy. The method, which does not rely on a time evolution, provides an extremely efficient way to compare the relative retention properties of metal-insulator-metal structures. It requires a small number of iterations and may be used for statistical analysis. The presented approach is used to compare the relative robustness of a single layer ZrO{sub 2} device with a double layer ZnO/ZrO{sub 2} one, and obtain results which are in good agreement with experimental data.

  5. One electron-controlled multiple-valued dynamic random-access-memory

    NASA Astrophysics Data System (ADS)

    Kye, H. W.; Song, B. N.; Lee, S. E.; Kim, J. S.; Shin, S. J.; Choi, J. B.; Yu, Y.-S.; Takahashi, Y.

    2016-02-01

    We propose a new architecture for a dynamic random-access-memory (DRAM) capable of storing multiple values by using a single-electron transistor (SET). The gate of a SET is designed to be connected to a plurality of DRAM unit cells that are arrayed at intersections of word lines and bitlines. In this SET-DRAM hybrid scheme, the multiple switching characteristics of SET enables multiple value data stored in a DRAM unit cell, and this increases the storage functionality of the device. Moreover, since refreshing data requires only a small amount of SET driving current, this enables device operating with low standby power consumption.

  6. Spin-transfer-torque efficiency enhanced by edge-damage of perpendicular magnetic random access memories

    SciTech Connect

    Song, Kyungmi; Lee, Kyung-Jin

    2015-08-07

    We numerically investigate the effect of magnetic and electrical damages at the edge of a perpendicular magnetic random access memory (MRAM) cell on the spin-transfer-torque (STT) efficiency that is defined by the ratio of thermal stability factor to switching current. We find that the switching mode of an edge-damaged cell is different from that of an undamaged cell, which results in a sizable reduction in the switching current. Together with a marginal reduction of the thermal stability factor of an edge-damaged cell, this feature makes the STT efficiency large. Our results suggest that a precise edge control is viable for the optimization of STT-MRAM.

  7. Complementary resistive switching behavior induced by varying forming current compliance in resistance random access memory

    NASA Astrophysics Data System (ADS)

    Tseng, Yi-Ting; Tsai, Tsung-Ming; Chang, Ting-Chang; Shih, Chih-Cheng; Chang, Kuan-Chang; Zhang, Rui; Chen, Kai-Huang; Chen, Jung-Hui; Li, Yu-Chiuan; Lin, Chih-Yang; Hung, Ya-Chi; Syu, Yong-En; Zheng, Jin-Cheng; Sze, Simon M.

    2015-05-01

    In this study of resistance random access memory in a resistive switching film, the breakdown degree was controlled by varying forming current compliance. A SiOx layer was introduced into the ZnO layer of the structure to induce both typical bipolar resistive switching (RS) and complementary resistive switching (CRS). In addition, the SiOx layer-generated vacuum spaces in typical bipolar RS can be verified by electrical characteristics. Changing forming current compliance strikingly modifies the oxygen storage capacity of the inserted SiOx layer. CRS can be achieved, therefore, by tuning the oxygen ion storage behavior made possible by the SiOx layer.

  8. Microstructural Characterization in Reliability Measurement of Phase Change Random Access Memory

    NASA Astrophysics Data System (ADS)

    Bae, Junsoo; Hwang, Kyuman; Park, Kwangho; Jeon, Seongbu; Kang, Dae-hwan; Park, Soonoh; Ahn, Juhyeon; Kim, Seoksik; Jeong, Gitae; Chung, Chilhee

    2011-04-01

    The cell failures after cycling endurance in phase-change random access memory (PRAM) have been classified into three groups, which have been analyzed by transmission electron microscopy (TEM). Both stuck reset of the set state (D0) and stuck set of the reset state (D1) are due to a void created inside GeSbTe (GST) film or thereby lowering density of GST film. The decrease of the both set and reset resistances that leads to the tails from the reset distribution are induced from the Sb increase with cycles.

  9. Optical and electronic error correction schemes for highly parallel access memories

    NASA Astrophysics Data System (ADS)

    Neifeld, Mark A.; Hayes, Jerry D.

    1993-11-01

    We have fabricated and tested an optically addressed, parallel electronic Reed-Solomon decoder for use with parallel access optical memories. A comparison with various serial implementations has demonstrated that for many instances of code block size and error correction capability, the parallel approach is superior from the perspectives of VLSI layout area and decoding latency. The demonstrated Reed-Solomon parallel pipeline decoder operates on 60 bit input words and has been demonstrated at a clock rate of 5 MHz yielding a demonstrated data rate of 300 Mbps.

  10. Random access memory immune to single event upset using a T-resistor

    DOEpatents

    Ochoa, Jr., Agustin

    1989-01-01

    In a random access memory cell, a resistance "T" decoupling network in each leg of the cell reduces random errors caused by the interaction of energetic ions with the semiconductor material forming the cell. The cell comprises two parallel legs each containing a series pair of complementary MOS transistors having a common gate connected to the node between the transistors of the opposite leg. The decoupling network in each leg is formed by a series pair of resistors between the transistors together with a third resistor interconnecting the junction between the pair of resistors and the gate of the transistor pair forming the opposite leg of the cell.

  11. A random access memory immune to single event upset using a T-Resistor

    DOEpatents

    Ochoa, A. Jr.

    1987-10-28

    In a random access memory cell, a resistance ''T'' decoupling network in each leg of the cell reduces random errors caused by the interaction of energetic ions with the semiconductor material forming the cell. The cell comprises two parallel legs each containing a series pair of complementary MOS transistors having a common gate connected to the node between the transistors of the opposite leg. The decoupling network in each leg is formed by a series pair of resistors between the transistors together with a third resistor interconnecting the junction between the pair of resistors and the gate of the transistor pair forming the opposite leg of the cell. 4 figs.

  12. Hydrogen doping in HfO2 resistance change random access memory

    NASA Astrophysics Data System (ADS)

    Duncan, D.; Magyari-Köpe, B.; Nishi, Y.

    2016-01-01

    The structures and energies of hydrogen-doped monoclinic hafnium dioxide were calculated using density-functional theory. The electronic interactions are described within the LDA + U formalism, where on-site Coulomb corrections are applied to the 5d orbital electrons of Hf atoms and 2p orbital electrons of the O atoms. The effects of charge state, defect-defect interactions, and hydrogenation are investigated and compared with experiment. It is found that hydrogenation of HfO2 resistance-change random access memory devices energetically stabilizes the formation of oxygen vacancies and conductive vacancy filaments through multiple mechanisms, leading to improved switching characteristic and device yield.

  13. A stochastic simulation method for the assessment of resistive random access memory retention reliability

    NASA Astrophysics Data System (ADS)

    Berco, Dan; Tseng, Tseung-Yuen

    2015-12-01

    This study presents an evaluation method for resistive random access memory retention reliability based on the Metropolis Monte Carlo algorithm and Gibbs free energy. The method, which does not rely on a time evolution, provides an extremely efficient way to compare the relative retention properties of metal-insulator-metal structures. It requires a small number of iterations and may be used for statistical analysis. The presented approach is used to compare the relative robustness of a single layer ZrO2 device with a double layer ZnO/ZrO2 one, and obtain results which are in good agreement with experimental data.

  14. TiO2 thin film based transparent flexible resistive switching random access memory

    NASA Astrophysics Data System (ADS)

    Pham, Kim Ngoc; Dung Hoang, Van; Tran, Cao Vinh; Thang Phan, Bach

    2016-03-01

    In our work we have fabricated TiO2 based resistive switching devices both on transparent substrates (ITO, IGZO/glass) and transparent flexible substrate (ITO/PET). All devices demonstrate the reproducibility of forming free bipolar resistive switching with high transparency in the visible light range (∼80% at the wavelength of 550 nm). Particularly, transparent and flexible device exhibits stable resistive switching performance at the initial state (flat) and even after bending state up to 500 times with curvature radius of 10% compared to flat state. The achieved characteristics of resistive switching of TiO2 thin films seem to be promising for transparent flexible random access memory.

  15. Positive alcohol expectancies and drinking behavior: the influence of expectancy strength and memory accessibility.

    PubMed

    Palfai, T; Wood, M D

    2001-03-01

    College student drinkers (N = 314) participated in a health survey in which they (a) completed an alcohol-related memory association task (expectancy accessibility measure), (b) rated their positive expectancies about alcohol use (expectancy strength measure), and (c) reported their level of alcohol involvement. Hierarchical regression analyses showed that both expectancy accessibility and expectancy strength predicted frequency of alcohol use and alcohol-related problems. Moreover, moderational analyses showed that the association between expectancy strength and frequency of alcohol use was greater for those who generated more alcohol responses on the expectancy association task. These findings suggest that the outcome association measure and Likert scale ratings of expectancies may assess distinct properties of expectancy representations, which may have independent and interactive effects on different aspects of drinking behavior. PMID:11255940

  16. Intrinsic Hydrophobicity of Rammed Earth

    NASA Astrophysics Data System (ADS)

    Holub, M.; Stone, C.; Balintova, M.; Grul, R.

    2015-11-01

    Rammed earth is well known for its vapour diffusion properties, its ability to regulate humidity within the built environment. Rammed earth is also an aesthetically iconic material such as marble or granite and therefore is preferably left exposed. However exposed rammed earth is often coated with silane/siloxane water repellents or the structure is modified architecturally (large roof overhangs) to accommodate for the hydrophilic nature of the material. This paper sets out to find out optimal hydrophobicity for rammed earth based on natural composite fibres and surface coating without adversely affecting the vapour diffusivity of the material. The material is not required to be waterproof, but should resist at least driving rain. In order to evaluate different approaches to increase hydrophobicity of rammed earth surface, peat fibres and four types of repellents were used.

  17. Analyzing the Energy and Power Consumption of Remote Memory Accesses in the OpenSHMEM Model

    SciTech Connect

    Jana, Siddhartha; Hernandez, Oscar R; Poole, Stephen W; Hsu, Chung-Hsing; Chapman, Barbara

    2014-01-01

    PGAS models like OpenSHMEM provide interfaces to explicitly initiate one-sided remote memory accesses among processes. In addition, the model also provides synchronizing barriers to ensure a consistent view of the distributed memory at different phases of an application. The incorrect use of such interfaces affects the scalability achievable while using a parallel programming model. This study aims at understanding the effects of these constructs on the energy and power consumption behavior of OpenSHMEM applications. Our experiments show that cost incurred in terms of the total energy and power consumed depends on multiple factors across the software and hardware stack. We conclude that there is a significant impact on the power consumed by the CPU and DRAM due to multiple factors including the design of the data transfer patterns within an application, the design of the communication protocols within a middleware, the architectural constraints laid by the interconnect solutions, and also the levels of memory hierarchy within a compute node. This work motivates treating energy and power consumption as important factors while designing compute solutions for current and future distributed systems.

  18. Temperature dependence of resistive switching behaviors in resistive random access memory based on graphene oxide film

    NASA Astrophysics Data System (ADS)

    Yi, Mingdong; Cao, Yong; Ling, Haifeng; Du, Zhuzhu; Wang, Laiyuan; Yang, Tao; Fan, Quli; Xie, Linghai; Huang, Wei

    2014-05-01

    We reported resistive switching behaviors in the resistive random access memory (RRAM) devices based on the different annealing temperatures of graphene oxide (GO) film as active layers. It was found that the resistive switching characteristics of an indium tin oxide (ITO)/GO/Ag structure have a strong dependence on the annealing temperature of GO film. When the annealing temperature of the GO film was 20 °C, the devices showed typical write-once-read-many-times (WORM) type memory behaviors, which have good memory performance with a higher ON/OFF current ratio (˜104), the higher the high resistance state (HRS)/low resistance state (LRS) ratio (˜105) and stable retention characteristics (>103 s) under lower programming voltage (-1 V and -0.5 V). With the increasing annealing temperature of GO film, the resistive switching behavior of RRAM devices gradually weakened and eventually disappeared. This phenomenon could be understood by the different energy level distributions of the charge traps in GO film, and the different charge injection ability from the Ag electrode to GO film, which is caused by the different annealing temperatures of the GO film.

  19. Temperature dependence of resistive switching behaviors in resistive random access memory based on graphene oxide film.

    PubMed

    Yi, Mingdong; Cao, Yong; Ling, Haifeng; Du, Zhuzhu; Wang, Laiyuan; Yang, Tao; Fan, Quli; Xie, Linghai; Huang, Wei

    2014-05-01

    We reported resistive switching behaviors in the resistive random access memory (RRAM) devices based on the different annealing temperatures of graphene oxide (GO) film as active layers. It was found that the resistive switching characteristics of an indium tin oxide (ITO)/GO/Ag structure have a strong dependence on the annealing temperature of GO film. When the annealing temperature of the GO film was 20 °C, the devices showed typical write-once-read-many-times (WORM) type memory behaviors, which have good memory performance with a higher ON/OFF current ratio (∼10(4)), the higher the high resistance state (HRS)/low resistance state (LRS) ratio (∼10(5)) and stable retention characteristics (>10(3) s) under lower programming voltage (-1 V and -0.5 V). With the increasing annealing temperature of GO film, the resistive switching behavior of RRAM devices gradually weakened and eventually disappeared. This phenomenon could be understood by the different energy level distributions of the charge traps in GO film, and the different charge injection ability from the Ag electrode to GO film, which is caused by the different annealing temperatures of the GO film. PMID:24739543

  20. A Built-In Self-Test Structure (BIST) for Resistive RAMs characterization: Application to bipolar OxRRAM

    NASA Astrophysics Data System (ADS)

    Aziza, H.; Bocquet, M.; Moreau, M.; Portal, J.-M.

    2015-01-01

    Resistive Random Access Memory (RRAM) is a form of nonvolatile storage that operates by changing the resistance of a specially formulated solid dielectric material [1]. Among RRAMs, oxide-based Resistive RAMs (so-called OxRRAMs) are promising candidates due their compatibility with CMOS processes and high ON/OFF resistance ratio. Common problems with OxRRAM are related to high variability in operating conditions and low yield. OxRRAM variability mainly impact ON/OFF resistance ratio. This ratio is a key parameter to determine the overall performance of an OxRRAM memory. In this context, the presented built-in structure allows collecting statistical data related to the OxRRAM memory array (ON/OFF resistance distributions) for reliability assessment of the technology.

  1. Interface engineered HfO2-based 3D vertical ReRAM

    NASA Astrophysics Data System (ADS)

    Hudec, Boris; Wang, I.-Ting; Lai, Wei-Li; Chang, Che-Chia; Jančovič, Peter; Fröhlich, Karol; Mičušík, Matej; Omastová, Mária; Hou, Tuo-Hung

    2016-06-01

    We demonstrate a double-layer 3D vertical resistive random access memory (ReRAM) stack implementing a Pt/HfO2/TiN memory cell. The HfO2 switching layer is grown by atomic layer deposition on the sidewall of a SiO2/TiN/SiO2/TiN/SiO2 multilayer pillar. A steep vertical profile was achieved using CMOS-compatible TiN dry etching. We employ in situ TiN bottom interface engineering by ozone, which results in (a) significant forming voltage reduction which allows for forming-free operation in AC pulsed mode, and (b) non-linearity tuning of low resistance state by current compliance during Set operation. The vertical ReRAM shows excellent read and write disturb immunity between vertically stacked cells, retention over 104 s and excellent switching stability at 400 K. Endurance of 107 write cycles was achieved using 100 ns wide AC pulses while fast switching speed using pulses of only 10 ns width is also demonstrated. The active switching region was evaluated to be located closer to the bottom interface which allows for the observed high endurance.

  2. Synergistic effects of total ionizing dose on single event upset sensitivity in static random access memory under proton irradiation

    NASA Astrophysics Data System (ADS)

    Xiao, Yao; Guo, Hong-Xia; Zhang, Feng-Qi; Zhao, Wen; Wang, Yan-Ping; Zhang, Ke-Ying; Ding, Li-Li; Fan, Xue; Luo, Yin-Hong; Wang, Yuan-Ming

    2014-11-01

    Synergistic effects of the total ionizing dose (TID) on the single event upset (SEU) sensitivity in static random access memories (SRAMs) were studied by using protons. The total dose was cumulated with high flux protons during the TID exposure, and the SEU cross section was tested with low flux protons at several cumulated dose steps. Because of the radiation-induced off-state leakage current increase of the CMOS transistors, the noise margin became asymmetric and the memory imprint effect was observed.

  3. Daily access to sucrose impairs aspects of spatial memory tasks reliant on pattern separation and neural proliferation in rats.

    PubMed

    Reichelt, Amy C; Morris, Margaret J; Westbrook, Reginald Frederick

    2016-07-01

    High sugar diets reduce hippocampal neurogenesis, which is required for minimizing interference between memories, a process that involves "pattern separation." We provided rats with 2 h daily access to a sucrose solution for 28 d and assessed their performance on a spatial memory task. Sucrose consuming rats discriminated between objects in novel and familiar locations when there was a large spatial separation between the objects, but not when the separation was smaller. Neuroproliferation markers in the dentate gyrus of the sucrose-consuming rats were reduced relative to controls. Thus, sucrose consumption impaired aspects of spatial memory and reduced hippocampal neuroproliferation. PMID:27317199

  4. Dual operation characteristics of resistance random access memory in indium-gallium-zinc-oxide thin film transistors

    SciTech Connect

    Yang, Jyun-Bao; Chen, Yu-Ting; Chu, Ann-Kuo; Chang, Ting-Chang; Huang, Jheng-Jie; Chen, Yu-Chun; Tseng, Hsueh-Chih; Sze, Simon M.

    2014-04-14

    In this study, indium-gallium-zinc-oxide thin film transistors can be operated either as transistors or resistance random access memory devices. Before the forming process, current-voltage curve transfer characteristics are observed, and resistance switching characteristics are measured after a forming process. These resistance switching characteristics exhibit two behaviors, and are dominated by different mechanisms. The mode 1 resistance switching behavior is due to oxygen vacancies, while mode 2 is dominated by the formation of an oxygen-rich layer. Furthermore, an easy approach is proposed to reduce power consumption when using these resistance random access memory devices with the amorphous indium-gallium-zinc-oxide thin film transistor.

  5. Memory interface simulator: A computer design aid

    NASA Technical Reports Server (NTRS)

    Taylor, D. S.; Williams, T.; Weatherbee, J. E.

    1972-01-01

    Results are presented of a study conducted with a digital simulation model being used in the design of the Automatically Reconfigurable Modular Multiprocessor System (ARMMS), a candidate computer system for future manned and unmanned space missions. The model simulates the activity involved as instructions are fetched from random access memory for execution in one of the system central processing units. A series of model runs measured instruction execution time under various assumptions pertaining to the CPU's and the interface between the CPU's and RAM. Design tradeoffs are presented in the following areas: Bus widths, CPU microprogram read only memory cycle time, multiple instruction fetch, and instruction mix.

  6. False Operation of Static Random Access Memory Cells under Alternating Current Power Supply Voltage Variation

    NASA Astrophysics Data System (ADS)

    Sawada, Takuya; Takata, Hidehiro; Nii, Koji; Nagata, Makoto

    2013-04-01

    Static random access memory (SRAM) cores exhibit susceptibility against power supply voltage variation. False operation is investigated among SRAM cells under sinusoidal voltage variation on power lines introduced by direct RF power injection. A standard SRAM core of 16 kbyte in a 90 nm 1.5 V technology is diagnosed with built-in self test and on-die noise monitor techniques. The sensitivity of bit error rate is shown to be high against the frequency of injected voltage variation, while it is not greatly influenced by the difference in frequency and phase against SRAM clocking. It is also observed that the distribution of false bits is substantially random in a cell array.

  7. Low-energy Resistive Random Access Memory Devices with No Need for a Compliance Current

    PubMed Central

    Xu, Zedong; Yu, Lina; Wu, Yong; Dong, Chang; Deng, Ning; Xu, Xiaoguang; Miao, J.; Jiang, Yong

    2015-01-01

    A novel resistive random access memory device is designed with SrTiO3/ La2/3Sr1/3MnO3 (LSMO)/MgAl2O4 (MAO)/Cu structure, in which metallic epitaxial LSMO is employed as the bottom electrode rather than traditional metal materials. In this device, the critical external compliance current is no longer necessary due to the high self-resistance of LSMO. The LMSO bottom electrode can act as a series resistor to offer a compliance current during the set process. Besides, the device also has excellent switching features which are originated in the formation of Cu filaments under external voltage. Therefore it provides the possibility of reducing power consumption and accelerating the commercialization of resistive switching devices. PMID:25982101

  8. Low-energy Resistive Random Access Memory Devices with No Need for a Compliance Current

    NASA Astrophysics Data System (ADS)

    Xu, Zedong; Yu, Lina; Wu, Yong; Dong, Chang; Deng, Ning; Xu, Xiaoguang; Miao, J.; Jiang, Yong

    2015-05-01

    A novel resistive random access memory device is designed with SrTiO3/ La2/3Sr1/3MnO3 (LSMO)/MgAl2O4 (MAO)/Cu structure, in which metallic epitaxial LSMO is employed as the bottom electrode rather than traditional metal materials. In this device, the critical external compliance current is no longer necessary due to the high self-resistance of LSMO. The LMSO bottom electrode can act as a series resistor to offer a compliance current during the set process. Besides, the device also has excellent switching features which are originated in the formation of Cu filaments under external voltage. Therefore it provides the possibility of reducing power consumption and accelerating the commercialization of resistive switching devices.

  9. Simulation study on heat conduction of a nanoscale phase-change random access memory cell.

    PubMed

    Kim, Junho; Song, Ki-Bong

    2006-11-01

    We have investigated heat transfer characteristics of a nano-scale phase-change random access memory (PRAM) cell using finite element method (FEM) simulation. Our PRAM cell is based on ternary chalcogenide alloy, Ge2Sb2Te5 (GST), which is used as a recording layer. For contact area of 100 x 100 nm2, simulations of crystallization and amorphization processes were carried out. Physical quantities such as electric conductivity, thermal conductivity, and specific heat were treated as temperature-dependent parameters. Through many simulations, it is concluded that one can reduce set current by decreasing both electric conductivities of amorphous GST and crystalline GST, and in addition to these conditions by decreasing electric conductivity of molten GST one can also reduce reset current significantly. PMID:17252792

  10. Characteristics and mechanism study of cerium oxide based random access memories

    SciTech Connect

    Hsieh, Cheng-Chih; Roy, Anupam; Rai, Amritesh; Chang, Yao-Feng; Banerjee, Sanjay K.

    2015-04-27

    In this work, low operating voltage and high resistance ratio of different resistance states of binary transition metal oxide based resistive random access memories (RRAMs) are demonstrated. Binary transition metal oxides with high dielectric constant have been explored for RRAM application for years. However, CeO{sub x} is considered as a relatively new material to other dielectrics. Since research on CeO{sub x} based RRAM is still at preliminary stage, fundamental characteristics of RRAM such as scalability and mechanism studies need to be done before moving further. Here, we show very high operation window and low switching voltage of CeO{sub x} RRAMs and also compare electrical performance of Al/CeO{sub x}/Au system between different thin film deposition methods and discuss characteristics and resistive switching mechanism.

  11. Novel Capacitor Structure Using Sidewall Spacer for Highly Reliable Ferroelectric Random Access Memory Device

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Ho; Park, Jung-Hoon; Song, Yoon-Jong; Jang, Nak-Won; Joo, Heung-Jin; Kang, Seung-Kuk; Joo, Seok-Ho; Lee, Sung-Young; Kim, Kinam

    2004-04-01

    Since ferroelectric capacitors prepared by 1-mask etching are degraded after the etching, we systematically investigated the origin of the degradation. It was found that the major degradation originates from the formation of the nonstoichiometric and amorphorized Pb(ZrxTi1-x)O3 (PZT) layer on the sidewall of the PZT film during etching of the bottom electrode (BE). Therefore, to eliminate the undesired etch-damaged layer, we developed a novel etching technology using a ferroelectric (FE) sidewall spacer, which results in the enhancement of the remnant polarization after completing the capacitor etching process. Using the novel FE sidewall spacer, the sensing margin of bit-line-developed voltage was improved to 400 mV, which can guarantee highy reliable high-density ferroelectric random access memory (FRAM) devices.

  12. Electrical Characterization of the RCA CDP1822SD Random Access Memory, Volume 1, Appendix a

    NASA Technical Reports Server (NTRS)

    Klute, A.

    1979-01-01

    Electrical characteristization tests were performed on 35 RCA CDP1822SD, 256-by-4-bit, CMOS, random access memories. The tests included three functional tests, AC and DC parametric tests, a series of schmoo plots, rise/fall time screening, and a data retention test. All tests were performed on an automated IC test system with temperatures controlled by a thermal airstream unit. All the functional tests, the data retention test, and the AC and DC parametric tests were performed at ambient temperatures of 25 C, -20 C, -55 C, 85 C, and 125 C. The schmoo plots were performed at ambient temperatures of 25 C, -55 C, and 125 C. The data retention test was performed at 25 C. Five devices failed one or more functional tests and four of these devices failed to meet the expected limits of a number of AC parametric tests. Some of the schmoo plots indicated a small degree of interaction between parameters.

  13. Understanding Electrical Conduction States in WO3 Thin Films Applied for Resistive Random-Access Memory

    NASA Astrophysics Data System (ADS)

    Ta, Thi Kieu Hanh; Pham, Kim Ngoc; Dao, Thi Bang Tam; Tran, Dai Lam; Phan, Bach Thang

    2016-05-01

    The electrical conduction and associated resistance switching mechanism of top electrode/WO3/bottom electrode devices [top electrode (TE): Ag, Ti; bottom electrode (BE): Pt, fluorine-doped tin oxide] have been investigated. The direction of switching and switching ability depended on both the top and bottom electrode material. Multiple electrical conduction mechanisms control the leakage current of such switching devices, including trap-controlled space-charge, ballistic, Ohmic, and Fowler-Nordheim tunneling effects. The transition between electrical conduction states is also linked to the switching (SET-RESET) process. This is the first report of ballistic conduction in research into resistive random-access memory. The associated resistive switching mechanisms are also discussed.

  14. Low-energy Resistive Random Access Memory Devices with No Need for a Compliance Current.

    PubMed

    Xu, Zedong; Yu, Lina; Wu, Yong; Dong, Chang; Deng, Ning; Xu, Xiaoguang; Miao, J; Jiang, Yong

    2015-01-01

    A novel resistive random access memory device is designed with SrTiO3/ La2/3Sr1/3MnO3 (LSMO)/MgAl2O4 (MAO)/Cu structure, in which metallic epitaxial LSMO is employed as the bottom electrode rather than traditional metal materials. In this device, the critical external compliance current is no longer necessary due to the high self-resistance of LSMO. The LMSO bottom electrode can act as a series resistor to offer a compliance current during the set process. Besides, the device also has excellent switching features which are originated in the formation of Cu filaments under external voltage. Therefore it provides the possibility of reducing power consumption and accelerating the commercialization of resistive switching devices. PMID:25982101

  15. Atomistic study of dynamics for metallic filament growth in conductive-bridge random access memory.

    PubMed

    Qin, Shengjun; Liu, Zhan; Zhang, Guo; Zhang, Jinyu; Sun, Yaping; Wu, Huaqiang; Qian, He; Yu, Zhiping

    2015-04-14

    The growth dynamics for metallic filaments in conductive-bridge resistive-switching random access memory (CBRAM) are studied using the kinetic Monte Carlo (KMC) method. The physical process at the atomistic level is revealed in explaining the experimental observation that filament growth can originate at either the cathode or the anode. The statistical nature of the filament growth is best shown by the random topography of dendrite-like conductive paths obtained. Critical material properties, such as charged-particle mobility in the switching layer of a solid electrolyte or a dielectric, are mapped to KMC model parameters through activation energy, etc. The accuracy of the simulator is established by the good agreement between the simulated forming time and the measured data. PMID:25750983

  16. Conductive-bridging random access memory: challenges and opportunity for 3D architecture.

    PubMed

    Jana, Debanjan; Roy, Sourav; Panja, Rajeswar; Dutta, Mrinmoy; Rahaman, Sheikh Ziaur; Mahapatra, Rajat; Maikap, Siddheswar

    2015-01-01

    The performances of conductive-bridging random access memory (CBRAM) have been reviewed for different switching materials such as chalcogenides, oxides, and bilayers in different structures. The structure consists of an inert electrode and one oxidized electrode of copper (Cu) or silver (Ag). The switching mechanism is the formation/dissolution of a metallic filament in the switching materials under external bias. However, the growth dynamics of the metallic filament in different switching materials are still debated. All CBRAM devices are switching under an operation current of 0.1 μA to 1 mA, and an operation voltage of ±2 V is also needed. The device can reach a low current of 5 pA; however, current compliance-dependent reliability is a challenging issue. Although a chalcogenide-based material has opportunity to have better endurance as compared to an oxide-based material, data retention and integration with the complementary metal-oxide-semiconductor (CMOS) process are also issues. Devices with bilayer switching materials show better resistive switching characteristics as compared to those with a single switching layer, especially a program/erase endurance of >10(5) cycles with a high speed of few nanoseconds. Multi-level cell operation is possible, but the stability of the high resistance state is also an important reliability concern. These devices show a good data retention of >10(5) s at >85°C. However, more study is needed to achieve a 10-year guarantee of data retention for non-volatile memory application. The crossbar memory is benefited for high density with low power operation. Some CBRAM devices as a chip have been reported for proto-typical production. This review shows that operation current should be optimized for few microamperes with a maintaining speed of few nanoseconds, which will have challenges and also opportunities for three-dimensional (3D) architecture. PMID:25977660

  17. Ultrafast switching in nanoscale phase-change random access memory with superlattice-like structures.

    PubMed

    Loke, Desmond; Shi, Luping; Wang, Weijie; Zhao, Rong; Yang, Hongxin; Ng, Lung-Tat; Lim, Kian-Guan; Chong, Tow-Chong; Yeo, Yee-Chia

    2011-06-24

    Phase-change random access memory cells with superlattice-like (SLL) GeTe/Sb(2)Te(3) were demonstrated to have excellent scaling performance in terms of switching speed and operating voltage. In this study, the correlations between the cell size, switching speed and operating voltage of the SLL cells were identified and investigated. We found that small SLL cells can achieve faster switching speed and lower operating voltage compared to the large SLL cells. Fast amorphization and crystallization of 300 ps and 1 ns were achieved in the 40 nm SLL cells, respectively, both significantly faster than those observed in the Ge(2)Sb(2)Te(5) (GST) cells of the same cell size. 40 nm SLL cells were found to switch with low amorphization voltage of 0.9 V when pulse-widths of 5 ns were employed, which is much lower than the 1.6 V required by the GST cells of the same cell size. These effects can be attributed to the fast heterogeneous crystallization, low thermal conductivity and high resistivity of the SLL structures. Nanoscale PCRAM with SLL structure promises applications in high speed and low power memory devices. PMID:21572204

  18. Does the mismatch negativity operate on a consciously accessible memory trace?

    PubMed

    Dykstra, Andrew R; Gutschalk, Alexander

    2015-11-01

    The extent to which the contents of short-term memory are consciously accessible is a fundamental question of cognitive science. In audition, short-term memory is often studied via the mismatch negativity (MMN), a change-related component of the auditory evoked response that is elicited by violations of otherwise regular stimulus sequences. The prevailing functional view of the MMN is that it operates on preattentive and even preconscious stimulus representations. We directly examined the preconscious notion of the MMN using informational masking and magnetoencephalography. Spectrally isolated and otherwise suprathreshold auditory oddball sequences were occasionally random rendered inaudible by embedding them in random multitone masker "clouds." Despite identical stimulation/task contexts and a clear representation of all stimuli in auditory cortex, MMN was only observed when the preceding regularity (that is, the standard stream) was consciously perceived. The results call into question the preconscious interpretation of MMN and raise the possibility that it might index partial awareness in the absence of overt behavior. PMID:26702432

  19. Does the mismatch negativity operate on a consciously accessible memory trace?

    PubMed Central

    Dykstra, Andrew R.; Gutschalk, Alexander

    2015-01-01

    The extent to which the contents of short-term memory are consciously accessible is a fundamental question of cognitive science. In audition, short-term memory is often studied via the mismatch negativity (MMN), a change-related component of the auditory evoked response that is elicited by violations of otherwise regular stimulus sequences. The prevailing functional view of the MMN is that it operates on preattentive and even preconscious stimulus representations. We directly examined the preconscious notion of the MMN using informational masking and magnetoencephalography. Spectrally isolated and otherwise suprathreshold auditory oddball sequences were occasionally random rendered inaudible by embedding them in random multitone masker “clouds.” Despite identical stimulation/task contexts and a clear representation of all stimuli in auditory cortex, MMN was only observed when the preceding regularity (that is, the standard stream) was consciously perceived. The results call into question the preconscious interpretation of MMN and raise the possibility that it might index partial awareness in the absence of overt behavior. PMID:26702432

  20. Context controls access to working and reference memory in the pigeon (Columba livia).

    PubMed

    Roberts, William A; Macpherson, Krista; Strang, Caroline

    2016-01-01

    The interaction between working and reference memory systems was examined under conditions in which salient contextual cues were presented during memory retrieval. Ambient colored lights (red or green) bathed the operant chamber during the presentation of comparison stimuli in delayed matching-to-sample training (working memory) and during the presentation of the comparison stimuli as S+ and S- cues in discrimination training (reference memory). Strong competition between memory systems appeared when the same contextual cue appeared during working and reference memory training. When different contextual cues were used, however, working memory was completely protected from reference memory interference. PMID:26781056

  1. An FPGA-Based Test-Bed for Reliability and Endurance Characterization of Non-Volatile Memory

    NASA Technical Reports Server (NTRS)

    Rao, Vikram; Patel, Jagdish; Patel, Janak; Namkung, Jeffrey

    2001-01-01

    Memory technologies are divided into two categories. The first category, nonvolatile memories, are traditionally used in read-only or read-mostly applications because of limited write endurance and slow write speed. These memories are derivatives of read only memory (ROM) technology, which includes erasable programmable ROM (EPROM), electrically-erasable programmable ROM (EEPROM), Flash, and more recent ferroelectric non-volatile memory technology. Nonvolatile memories are able to retain data in the absence of power. The second category, volatile memories, are random access memory (RAM) devices including SRAM and DRAM. Writing to these memories is fast and write endurance is unlimited, so they are most often used to store data that change frequently, but they cannot store data in the absence of power. Nonvolatile memory technologies with better future potential are FRAM, Chalcogenide, GMRAM, Tunneling MRAM, and Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) EEPROM.

  2. Memory.

    ERIC Educational Resources Information Center

    McKean, Kevin

    1983-01-01

    Discusses current research (including that involving amnesiacs and snails) into the nature of the memory process, differentiating between and providing examples of "fact" memory and "skill" memory. Suggests that three brain parts (thalamus, fornix, mammilary body) are involved in the memory process. (JN)

  3. Evaluation of Data Retention Characteristics for Ferroelectric Random Access Memories (FRAMs)

    NASA Technical Reports Server (NTRS)

    Sharma, Ashok K.; Teverovsky, Alexander

    2001-01-01

    Data retention and fatigue characteristics of 64 Kb lead zirconate titanate (PZT)-based Ferroelectric Random Access Memories (FRAMs) microcircuits manufactured by Ramtron were examined over temperature range from -85 C to +310 C for ceramic packaged parts and from -85 C to +175 C for plastic parts, during retention periods up to several thousand hours. Intrinsic failures, which were caused by a thermal degradation of the ferroelectric cells, occurred in ceramic parts after tens or hundreds hours of aging at temperatures above 200 C. The activation energy of the retention test failures was 1.05 eV and the extrapolated mean-time-to-failure (MTTF) at room temperature was estimated to be more than 280 years. Multiple write-read cycling (up to 3x10(exp 7)) during the fatigue testing of plastic and ceramic parts did not result in any parametric or functional failures. However, operational currents linearly decreased with the logarithm of number of cycles thus indicating fatigue process in PZT films. Plastic parts, that had more recent date code as compared to ceramic parts, appeared to be using die with improved process technology and showed significantly smaller changes in operational currents and data access times.

  4. Three-Year-Old Children Can Access Their Own Memory to Guide Responses on a Visual Matching Task

    ERIC Educational Resources Information Center

    Balcomb, Frances K.; Gerken, LouAnn

    2008-01-01

    Many models of learning rely on accessing internal knowledge states. Yet, although infants and young children are recognized to be proficient learners, the ability to act on metacognitive information is not thought to develop until early school years. In the experiments reported here, 3.5-year-olds demonstrated memory-monitoring skills by…

  5. Robotic Assisted Microsurgery - RAMS FY'97

    NASA Technical Reports Server (NTRS)

    1997-01-01

    JPL and Microdexterity Systems collaborated to develop new surgical capabilities. They developed a Robot Assisted Microsurgery (RAM) tool for surgeons to use for operating on the eye, ear, brain, and blood vessels with unprecedented dexterity. A surgeon can hold the surgical instrument with motions of 6 degrees of freedom with an accuracy of 25 microns in a 70 cu cm workspace. In 1996 a demonstration was performed to remove a microscopic particle from a simulated eyeball. In 1997, tests were performed at UCLA to compare telerobotics with mechanical operations. In 5 out of 7 tests, the RAM tool performed with a significant improvement of preciseness over mechanical operation. New design features include: (1) amplified forced feedback; (2) simultaneous slave robot instrumentation; (3) index control switch on master handle; and (4) tool control switches. Upgrades include: (1) increase in computational power; and (2) installation of hard disk memory storage device for independent operation and independent operation of forceps. In 1997 a final demonstration was performed using 2 telerobotics simultaneously in a microsurgery suture procedure to close a slit in a thin sheet of latex rubber which extended the capabilities of microsurgery procedures. After completing trials and demonstrations for the FDA the potential benefits for thousands of operations will be exposed.

  6. Tuning resistance states by thickness control in an electroforming-free nanometallic complementary resistance random access memory

    NASA Astrophysics Data System (ADS)

    Yang, Xiang; Lu, Yang; Lee, Jongho; Chen, I.-Wei

    2016-01-01

    Tuning low resistance state is crucial for resistance random access memory (RRAM) that aims to achieve optimal read margin and design flexibility. By back-to-back stacking two nanometallic bipolar RRAMs with different thickness into a complementary structure, we have found that its low resistance can be reliably tuned over several orders of magnitude. Such high tunability originates from the exponential thickness dependence of the high resistance state of nanometallic RRAM, in which electron wave localization in a random network gives rise to the unique scaling behavior. The complementary nanometallic RRAM provides electroforming-free, multi-resistance-state, sub-100 ns switching capability with advantageous characteristics for memory arrays.

  7. Multi-port, optically addressed RAM

    NASA Technical Reports Server (NTRS)

    Johnston, Alan R. (Inventor); Nixon, Robert H. (Inventor); Bergman, Larry A. (Inventor); Esener, Sadik (Inventor)

    1989-01-01

    A random access memory addressing system utilizing optical links between memory and the read/write logic circuits comprises addressing circuits including a plurality of light signal sources, a plurality of optical gates including optical detectors associated with the memory cells, and a holographic optical element adapted to reflect and direct the light signals to the desired memory cell locations. More particularly, it is a multi-port, binary computer memory for interfacing with a plurality of computers. There are a plurality of storage cells for containing bits of binary information, the storage cells being disposed at the intersections of a plurality of row conductors and a plurality of column conductors. There is interfacing logic for receiving information from the computers directing access to ones of the storage cells. There are first light sources associated with the interfacing logic for transmitting a first light beam with the access information modulated thereon. First light detectors are associated with the storage cells for receiving the first light beam, for generating an electrical signal containing the access information, and for conducting the electrical signal to the one of the storage cells to which it is directed. There are holographic optical elements for reflecting the first light beam from the first light sources to the first light detectors.

  8. Performance improvement of gadolinium oxide resistive random access memory treated by hydrogen plasma immersion ion implantation

    SciTech Connect

    Wang, Jer-Chyi Hsu, Chih-Hsien; Ye, Yu-Ren; Ai, Chi-Fong; Tsai, Wen-Fa

    2014-03-15

    Characteristics improvement of gadolinium oxide (Gd{sub x}O{sub y}) resistive random access memories (RRAMs) treated by hydrogen plasma immersion ion implantation (PIII) was investigated. With the hydrogen PIII treatment, the Gd{sub x}O{sub y} RRAMs exhibited low set/reset voltages and a high resistance ratio, which were attributed to the enhanced movement of oxygen ions within the Gd{sub x}O{sub y} films and the increased Schottky barrier height at Pt/Gd{sub x}O{sub y} interface, respectively. The resistive switching mechanism of Gd{sub x}O{sub y} RRAMs was dominated by Schottky emission, as proved by the area dependence of the resistance in the low resistance state. After the hydrogen PIII treatment, a retention time of more than 10{sup 4} s was achieved at an elevated measurement temperature. In addition, a stable cycling endurance with the resistance ratio of more than three orders of magnitude of the Gd{sub x}O{sub y} RRAMs can be obtained.

  9. Switching methods in magnetic random access memory for low power applications

    NASA Astrophysics Data System (ADS)

    Guchang, Han; Jiancheng, Huang; Cheow Hin, Sim; Tran, Michael; Sze Ter, Lim

    2015-06-01

    Effect of saturation magnetization (Ms) of the free layer (FL) on the switching current is analyzed for spin transfer torque (STT) magnetic random access memory (MRAM). For in-plane FL, critical switching current (Ic0) decreases as Ms decreases. However, reduction in Ms also results in a low thermal stability factor (Δ), which must be compensated through increasing shape anisotropy, thus limiting scalability. For perpendicular FL, Ic0 reduction by using low-Ms materials is actually at the expense of data retention. To save energy consumed by STT current, two electric field (EF) controlled switching methods are proposed. Our simulation results show that elliptical FL can be switched by an EF pulse with a suitable width. However, it is difficult to implement this type of switching in real MRAM devices due to the distribution of the required switching pulse widths. A reliable switching method is to use an Oersted field guided switching. Our simulation and experimental results show that the bi-directional magnetization switching could be realized by an EF with an external field as low as  ±5 Oe if the offset field could be removed.

  10. Solution-processed carbon nanotube thin-film complementary static random access memory

    NASA Astrophysics Data System (ADS)

    Geier, Michael L.; McMorrow, Julian J.; Xu, Weichao; Zhu, Jian; Kim, Chris H.; Marks, Tobin J.; Hersam, Mark C.

    2015-11-01

    Over the past two decades, extensive research on single-walled carbon nanotubes (SWCNTs) has elucidated their many extraordinary properties, making them one of the most promising candidates for solution-processable, high-performance integrated circuits. In particular, advances in the enrichment of high-purity semiconducting SWCNTs have enabled recent circuit demonstrations including synchronous digital logic, flexible electronics and high-frequency applications. However, due to the stringent requirements of the transistors used in complementary metal-oxide-semiconductor (CMOS) logic as well as the absence of sufficiently stable and spatially homogeneous SWCNT thin-film transistors, the development of large-scale SWCNT CMOS integrated circuits has been limited in both complexity and functionality. Here, we demonstrate the stable and uniform electronic performance of complementary p-type and n-type SWCNT thin-film transistors by controlling adsorbed atmospheric dopants and incorporating robust encapsulation layers. Based on these complementary SWCNT thin-film transistors, we simulate, design and fabricate arrays of low-power static random access memory circuits, achieving large-scale integration for the first time based on solution-processed semiconductors.

  11. Electrical Evaluation of RCA MWS5001D Random Access Memory, Volume 1

    NASA Technical Reports Server (NTRS)

    Klute, A.

    1979-01-01

    Electrical characterization and qualification tests were performed on the RCA MWS5001D, 1024 by 1-bit, CMOS, random access memory. Characterization tests were performed on five devices. The tests included functional tests, AC parametric worst case pattern selection test, determination of worst-case transition for setup and hold times and a series of schmoo plots. The qualification tests were performed on 32 devices and included a 2000 hour burn in with electrical tests performed at 0 hours and after 168, 1000, and 2000 hours of burn in. The tests performed included functional tests and AC and DC parametric tests. All of the tests in the characterization phase, with the exception of the worst-case transition test, were performed at ambient temperatures of 25, -55 and 125 C. The worst-case transition test was performed at 25 C. The preburn in electrical tests were performed at 25, -55, and 125 C. All burn in endpoint tests were performed at 25, -40, -55, 85, and 125 C.

  12. Single-crystalline CuO nanowires for resistive random access memory applications

    SciTech Connect

    Hong, Yi-Siang; Chen, Jui-Yuan; Huang, Chun-Wei; Chiu, Chung-Hua; Huang, Yu-Ting; Huang, Ting Kai; He, Ruo Shiuan; Wu, Wen-Wei

    2015-04-27

    Recently, the mechanism of resistive random access memory (RRAM) has been partly clarified and determined to be controlled by the forming and erasing of conducting filaments (CF). However, the size of the CF may restrict the application and development as devices are scaled down. In this work, we synthesized CuO nanowires (NW) (∼150 nm in diameter) to fabricate a CuO NW RRAM nanodevice that was much smaller than the filament (∼2 μm) observed in a bulk CuO RRAM device in a previous study. HRTEM indicated that the Cu{sub 2}O phase was generated after operation, which demonstrated that the filament could be minimize to as small as 3.8 nm when the device is scaled down. In addition, energy dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS) show the resistive switching of the dielectric layer resulted from the aggregated oxygen vacancies, which also match with the I-V fitting results. Those results not only verify the switching mechanism of CuO RRAM but also show RRAM has the potential to shrink in size, which will be beneficial to the practical application of RRAM devices.

  13. Solution-processed carbon nanotube thin-film complementary static random access memory.

    PubMed

    Geier, Michael L; McMorrow, Julian J; Xu, Weichao; Zhu, Jian; Kim, Chris H; Marks, Tobin J; Hersam, Mark C

    2015-11-01

    Over the past two decades, extensive research on single-walled carbon nanotubes (SWCNTs) has elucidated their many extraordinary properties, making them one of the most promising candidates for solution-processable, high-performance integrated circuits. In particular, advances in the enrichment of high-purity semiconducting SWCNTs have enabled recent circuit demonstrations including synchronous digital logic, flexible electronics and high-frequency applications. However, due to the stringent requirements of the transistors used in complementary metal-oxide-semiconductor (CMOS) logic as well as the absence of sufficiently stable and spatially homogeneous SWCNT thin-film transistors, the development of large-scale SWCNT CMOS integrated circuits has been limited in both complexity and functionality. Here, we demonstrate the stable and uniform electronic performance of complementary p-type and n-type SWCNT thin-film transistors by controlling adsorbed atmospheric dopants and incorporating robust encapsulation layers. Based on these complementary SWCNT thin-film transistors, we simulate, design and fabricate arrays of low-power static random access memory circuits, achieving large-scale integration for the first time based on solution-processed semiconductors. PMID:26344184

  14. High uniformity and improved nonlinearity by embedding nanocrystals in selector-less resistive random access memory.

    PubMed

    Banerjee, Writam; Lu, Nianduan; Li, Ling; Sun, Pengxiao; Liu, Qi; Lv, Hangbing; Long, Shibing; Liu, Ming

    2014-12-10

    The sneak path problem is one of the major hindrances for the application of high density 3D crossbar resistive random access memory (RRAM). For the selector-less RRAM devices, nonlinear (NL) current-voltage (I-V) characteristics are an alternative approach to minimize the sneak paths. In this work we have demonstrated metallic IrOx nanocrystal (IrOx-NC) based selector-less crossbar RRAM devices in an IrOx/AlOx/IrOx-NC/AlOx/W structure with very reliable hysteresis resistive switching of >10 000 cycles, stable multiple levels, and high temperature (HT) data retention. Moreover, an improvement in the NL behavior has been reported as compared to a pure high-κ AlOx RRAM. The origin of the NL nature has been discussed using the hopping model and Luittenger's 1D metal theory. The nonlinearity can be further improved by structure engineering and will improve the sensing margin of the devices, which is rewarding for crossbar array integration. PMID:25491764

  15. Development of battering ram vibrator system

    NASA Astrophysics Data System (ADS)

    Sun, F.; Chen, Z.; Lin, J.; Tong, X.

    2012-12-01

    This paper researched the battering ram vibrator system, by electric machinery we can control oil system of battering ram, we realized exact control of battering ram, after analyzed pseudorandom coding, code "0" and "1" correspond to rest and shake of battering ram, then we can get pseudorandom coding which is the same with battering ram vibrator. After testing , by the reference trace and single shot record, when we using pseudorandom coding mode, the ratio of seismic wavelet to correlation interfere is about 68 dB, while the general mode , the ratio of seismic wavelet to correlation interfere only is 27.9dB, by battering ram vibrator system, we can debase the correlation interfere which come from the single shaking frequency of battering ram, this system advanced the signal-to-noise ratio of seismic data, which can give direction of the application of battering ram vibrator in metal mine exploration and high resolving seismic exploration.

  16. Encoding and retrieval processes involved in the access of source information in the absence of item memory.

    PubMed

    Ball, B Hunter; DeWitt, Michael R; Knight, Justin B; Hicks, Jason L

    2014-09-01

    The current study sought to examine the relative contributions of encoding and retrieval processes in accessing contextual information in the absence of item memory using an extralist cuing procedure in which the retrieval cues used to query memory for contextual information were related to the target item but never actually studied. In Experiments 1 and 2, participants studied 1 category member (e.g., onion) from a variety of different categories and at test were presented with an unstudied category label (e.g., vegetable) to probe memory for item and source information. In Experiments 3 and 4, 1 member of unidirectional (e.g., credit or card) or bidirectional (e.g., salt or pepper) associates was studied, whereas the other unstudied member served as a test probe. When recall failed, source information was accessible only when items were processed deeply during encoding (Experiments 1 and 2) and when there was strong forward associative strength between the retrieval cue and target (Experiments 3 and 4). These findings suggest that a retrieval probe diagnostic of semantically related item information reinstantiates information bound in memory during encoding that results in reactivation of associated contextual information, contingent upon sufficient learning of the item itself and the association between the item and its context information. PMID:24933700

  17. Chemical state of Ag in Conducting Bridge Random Access Memory cells: a depth resolved X-ray Absorption Spectroscopy investigation.

    NASA Astrophysics Data System (ADS)

    d'Acapito, F.; Souchier, E.; Noe, P.; Blaise, P.; Bernard, M.; Jousseaume, V.

    2016-05-01

    Conducting Bridge Random Access Memories (CBRAM) are a promising substitute for FLASH technology but problems with limited retention of the low resistance ON state still hamper their massive deployment. Depth resolved X-ray Absorption Spectroscopy has been used to describe the chemical state of the atoms of the active electrode (in this case Ag) and to reveal the role of Sb as stabilizer of the metallic state.

  18. ViSA: a neurodynamic model for visuo-spatial working memory, attentional blink, and conscious access.

    PubMed

    Simione, Luca; Raffone, Antonino; Wolters, Gezinus; Salmas, Paola; Nakatani, Chie; Belardinelli, Marta Olivetti; van Leeuwen, Cees

    2012-10-01

    Two separate lines of study have clarified the role of selectivity in conscious access to visual information. Both involve presenting multiple targets and distracters: one simultaneously in a spatially distributed fashion, the other sequentially at a single location. To understand their findings in a unified framework, we propose a neurodynamic model for Visual Selection and Awareness (ViSA). ViSA supports the view that neural representations for conscious access and visuo-spatial working memory are globally distributed and are based on recurrent interactions between perceptual and access control processors. Its flexible global workspace mechanisms enable a unitary account of a broad range of effects: It accounts for the limited storage capacity of visuo-spatial working memory, attentional cueing, and efficient selection with multi-object displays, as well as for the attentional blink and associated sparing and masking effects. In particular, the speed of consolidation for storage in visuo-spatial working memory in ViSA is not fixed but depends adaptively on the input and recurrent signaling. Slowing down of consolidation due to weak bottom-up and recurrent input as a result of brief presentation and masking leads to the attentional blink. Thus, ViSA goes beyond earlier 2-stage and neuronal global workspace accounts of conscious processing limitations. PMID:22823385

  19. Physical and chemical mechanisms in oxide-based resistance random access memory

    NASA Astrophysics Data System (ADS)

    Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Zhang, Rui; Hung, Ya-Chi; Syu, Yong-En; Chang, Yao-Feng; Chen, Min-Chen; Chu, Tian-Jian; Chen, Hsin-Lu; Pan, Chih-Hung; Shih, Chih-Cheng; Zheng, Jin-Cheng; Sze, Simon M.

    2015-03-01

    In this review, we provide an overview of our work in resistive switching mechanisms on oxide-based resistance random access memory (RRAM) devices. Based on the investigation of physical and chemical mechanisms, we focus on its materials, device structures, and treatment methods so as to provide an in-depth perspective of state-of-the-art oxide-based RRAM. The critical voltage and constant reaction energy properties were found, which can be used to prospectively modulate voltage and operation time to control RRAM device working performance and forecast material composition. The quantized switching phenomena in RRAM devices were demonstrated at ultra-cryogenic temperature (4K), which is attributed to the atomic-level reaction in metallic filament. In the aspect of chemical mechanisms, we use the Coulomb Faraday theorem to investigate the chemical reaction equations of RRAM for the first time. We can clearly observe that the first-order reaction series is the basis for chemical reaction during reset process in the study. Furthermore, the activation energy of chemical reactions can be extracted by changing temperature during the reset process, from which the oxygen ion reaction process can be found in the RRAM device. As for its materials, silicon oxide is compatible to semiconductor fabrication lines. It is especially promising for the silicon oxide-doped metal technology to be introduced into the industry. Based on that, double-ended graphene oxide-doped silicon oxide based via-structure RRAM with filament self-aligning formation, and self-current limiting operation ability is demonstrated. The outstanding device characteristics are attributed to the oxidation and reduction of graphene oxide flakes formed during the sputter process. Besides, we have also adopted a new concept of supercritical CO2 fluid treatment to efficiently reduce the operation current of RRAM devices for portable electronic applications.

  20. Physical and chemical mechanisms in oxide-based resistance random access memory.

    PubMed

    Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Zhang, Rui; Hung, Ya-Chi; Syu, Yong-En; Chang, Yao-Feng; Chen, Min-Chen; Chu, Tian-Jian; Chen, Hsin-Lu; Pan, Chih-Hung; Shih, Chih-Cheng; Zheng, Jin-Cheng; Sze, Simon M

    2015-01-01

    In this review, we provide an overview of our work in resistive switching mechanisms on oxide-based resistance random access memory (RRAM) devices. Based on the investigation of physical and chemical mechanisms, we focus on its materials, device structures, and treatment methods so as to provide an in-depth perspective of state-of-the-art oxide-based RRAM. The critical voltage and constant reaction energy properties were found, which can be used to prospectively modulate voltage and operation time to control RRAM device working performance and forecast material composition. The quantized switching phenomena in RRAM devices were demonstrated at ultra-cryogenic temperature (4K), which is attributed to the atomic-level reaction in metallic filament. In the aspect of chemical mechanisms, we use the Coulomb Faraday theorem to investigate the chemical reaction equations of RRAM for the first time. We can clearly observe that the first-order reaction series is the basis for chemical reaction during reset process in the study. Furthermore, the activation energy of chemical reactions can be extracted by changing temperature during the reset process, from which the oxygen ion reaction process can be found in the RRAM device. As for its materials, silicon oxide is compatible to semiconductor fabrication lines. It is especially promising for the silicon oxide-doped metal technology to be introduced into the industry. Based on that, double-ended graphene oxide-doped silicon oxide based via-structure RRAM with filament self-aligning formation, and self-current limiting operation ability is demonstrated. The outstanding device characteristics are attributed to the oxidation and reduction of graphene oxide flakes formed during the sputter process. Besides, we have also adopted a new concept of supercritical CO2 fluid treatment to efficiently reduce the operation current of RRAM devices for portable electronic applications. PMID:25873842

  1. Current Development Status and Future Challenges of Ferroelectric Random Access Memory Technologies

    NASA Astrophysics Data System (ADS)

    Lee, Sungyung; Kim, Kinam

    2006-04-01

    For ferroelectric random access memory (FRAM) to be beneficial in future mobile devices, high-density FRAM with nm scaled cell should be developed. We have succeeded in scaling further the cell size of one-pass transistor and one-storage capacitor (1T1C) FRAM down to 0.27 μm2 at 150 nm technology node. Owing to new SrRuO3 (SRO) electrode technology along with ultrathin PbZrTiO3 (PZT) using metal organic chemical vapor deposition (MOCVD) technology, two-dimensional (2-D) metal-insulator-metal (MIM) ferroelectric capacitor was successfully scaled down vertically to 200 nm. By the application of a new double hard mask capacitor etching technology, 0.11-μm2-area 200-nm-thick 2-D PZT capacitor was successfully isolated with 180 nm spacing. As a result, a high remanent polarization of 40 μC/cm2 was obtained at 1.6 V on a 0.11 μm2 ferroelectric storage capacitor of the 0.27 μm2 cell 1T1C FRAM. Great advances in three-dimensional (3-D) ferroelectric capacitor, which is essential for 6-8 F2 cell 1T1C FRAM at nm scaled technology node, have been made by introducing a new atomic layer deposition (ALD) method for 3-D electrode and a novel MOCVD PZT deposition for 3-D PZT. As a result, for the first time, robust hysteresis was obtained from a 3-D PZT capacitor.

  2. Analog Nonvolatile Computer Memory Circuits

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd

    2007-01-01

    In nonvolatile random-access memory (RAM) circuits of a proposed type, digital data would be stored in analog form in ferroelectric field-effect transistors (FFETs). This type of memory circuit would offer advantages over prior volatile and nonvolatile types: In a conventional complementary metal oxide/semiconductor static RAM, six transistors must be used to store one bit, and storage is volatile in that data are lost when power is turned off. In a conventional dynamic RAM, three transistors must be used to store one bit, and the stored bit must be refreshed every few milliseconds. In contrast, in a RAM according to the proposal, data would be retained when power was turned off, each memory cell would contain only two FFETs, and the cell could store multiple bits (the exact number of bits depending on the specific design). Conventional flash memory circuits afford nonvolatile storage, but they operate at reading and writing times of the order of thousands of conventional computer memory reading and writing times and, hence, are suitable for use only as off-line storage devices. In addition, flash memories cease to function after limited numbers of writing cycles. The proposed memory circuits would not be subject to either of these limitations. Prior developmental nonvolatile ferroelectric memories are limited to one bit per cell, whereas, as stated above, the proposed memories would not be so limited. The design of a memory circuit according to the proposal must reflect the fact that FFET storage is only partly nonvolatile, in that the signal stored in an FFET decays gradually over time. (Retention times of some advanced FFETs exceed ten years.) Instead of storing a single bit of data as either a positively or negatively saturated state in a ferroelectric device, each memory cell according to the proposal would store two values. The two FFETs in each cell would be denoted the storage FFET and the control FFET. The storage FFET would store an analog signal value

  3. Accessibility

    MedlinePlus

    ... www.nlm.nih.gov/medlineplus/accessibility.html MedlinePlus Accessibility To use the sharing features on this page, ... Subscribe to RSS Follow us Disclaimers Copyright Privacy Accessibility Quality Guidelines Viewers & Players MedlinePlus Connect for EHRs ...

  4. Trip Report: RAM-PAC International

    SciTech Connect

    Jaques, Al; /Fermilab

    1988-09-09

    In the final design of the DO Detector, the three cryostats (CC and both EC's) will ride on a pair of hardened ways so as to move the EC's out and away from the CC cryostat to provide access between cryostats for repairs and such. Each of the cryostats sits on a carriage which has a pair of Tychoway rollers placed at each corner to roll on the hardened ways. When in position, the full weight of the cryostats is to be relieved from the rollers with the use of a pair of 90-ton jacks flanking the pair of rollers at each corner. Due to confined space, these jacks had to be custom made, triple cylinder, single block units. Five manufacturers were presented with the problem and three came back with proposals. All three satisfied the technical requirements but Ram-Pac International was easily the lowest priced.

  5. System for loading executable code into volatile memory in a downhole tool

    DOEpatents

    Hall, David R.; Bartholomew, David B.; Johnson, Monte L.

    2007-09-25

    A system for loading an executable code into volatile memory in a downhole tool string component comprises a surface control unit comprising executable code. An integrated downhole network comprises data transmission elements in communication with the surface control unit and the volatile memory. The executable code, stored in the surface control unit, is not permanently stored in the downhole tool string component. In a preferred embodiment of the present invention, the downhole tool string component comprises boot memory. In another embodiment, the executable code is an operating system executable code. Preferably, the volatile memory comprises random access memory (RAM). A method for loading executable code to volatile memory in a downhole tool string component comprises sending the code from the surface control unit to a processor in the downhole tool string component over the network. A central processing unit writes the executable code in the volatile memory.

  6. Experiment of rocket-ram annular combustor

    NASA Astrophysics Data System (ADS)

    Yatsuyanagi, N.; Sakamoto, H.; Sato, K.; Ono, F.; Sasaki, M.; Takahashi, M.

    In this experiment, the double-nozzle type of rocket-ram annular combustor with a total thrust of 5kN was designed and tested with varying ratios of thrust produced by rocket and ram. Thrust and pressure distribution along the common expansion nozzle, i.e., the ram combustor nozzle, were measured to investigate the effect of interaction of the two expansion gases on thrust. Enhancement of specific impulse was verified by the experiments. That is, the specific impulse gains in rocket-ram parallel operation, the ratio of rocket thrust to ram thrust being 50 to 50, were found to be 190 percent of gains in pure rocket operation.

  7. Contexts and Control Operations Used in Accessing List-Specific, Generalized, and Semantic Memories

    ERIC Educational Resources Information Center

    Humphreys, Michael S.; Murray, Krista L.; Maguire, Angela M.

    2009-01-01

    The human ability to focus memory retrieval operations on a particular list, episode or memory structure has not been fully appreciated or documented. In Experiment 1-3, we make it increasingly difficult for participants to switch between a less recent list (multiple study opportunities), and a more recent list (single study opportunity). Task…

  8. Speed and Accuracy of Accessing Information in Working Memory: An Individual Differences Investigation of Focus Switching

    ERIC Educational Resources Information Center

    Unsworth, Nash; Engle, Randall W.

    2008-01-01

    Three experiments examined the nature of individual differences in switching the focus of attention in working memory. Participants performed 3 versions of a continuous counting task that required successive updating and switching between counts. Across all 3 experiments, individual differences in working memory span and fluid intelligence were…

  9. Retrieval practice enhances the accessibility but not the quality of memory.

    PubMed

    Sutterer, David W; Awh, Edward

    2016-06-01

    Numerous studies have demonstrated that retrieval from long-term memory (LTM) can enhance subsequent memory performance, a phenomenon labeled the retrieval practice effect. However, the almost exclusive reliance on categorical stimuli in this literature leaves open a basic question about the nature of this improvement in memory performance. It has not yet been determined whether retrieval practice improves the probability of successful memory retrieval or the quality of the retrieved representation. To answer this question, we conducted three experiments using a mixture modeling approach (Zhang & Luck, 2008) that provides a measure of both the probability of recall and the quality of the recalled memories. Subjects attempted to memorize the color of 400 unique shapes. After every 10 images were presented, subjects either recalled the last 10 colors (the retrieval practice condition) by clicking on a color wheel with each shape as a retrieval cue or they participated in a control condition that involved no further presentations (Experiment 1) or restudy of the 10 shape/color associations (Experiments 2 and 3). Performance in a subsequent delayed recall test revealed a robust retrieval practice effect. Subjects recalled a significantly higher proportion of items that they had previously retrieved relative to items that were untested or that they had restudied. Interestingly, retrieval practice did not elicit any improvement in the precision of the retrieved memories. The same empirical pattern also was observed following delays of greater than 24 hours. Thus, retrieval practice increases the probability of successful memory retrieval but does not improve memory quality. PMID:26404635

  10. Ferroelectric tunneling element and memory applications which utilize the tunneling element

    DOEpatents

    Kalinin, Sergei V [Knoxville, TN; Christen, Hans M [Knoxville, TN; Baddorf, Arthur P [Knoxville, TN; Meunier, Vincent [Knoxville, TN; Lee, Ho Nyung [Oak Ridge, TN

    2010-07-20

    A tunneling element includes a thin film layer of ferroelectric material and a pair of dissimilar electrically-conductive layers disposed on opposite sides of the ferroelectric layer. Because of the dissimilarity in composition or construction between the electrically-conductive layers, the electron transport behavior of the electrically-conductive layers is polarization dependent when the tunneling element is below the Curie temperature of the layer of ferroelectric material. The element can be used as a basis of compact 1R type non-volatile random access memory (RAM). The advantages include extremely simple architecture, ultimate scalability and fast access times generic for all ferroelectric memories.

  11. An SEU (single event upset) tolerant memory cell derived from fundamental studies of SEU mechanisms in SRAM (static random access memories)

    SciTech Connect

    Weaver, H.T.; Axness, C.L.; McBrayer, J.D.; Browning, J.S.; Fu, J.S.; Ochoa, A. Jr.; Koga, R.

    1987-01-01

    A new single event upset (SEU) hardening concept, an LRAM cell, is demonstrated theoretically and experimentally. As basis for the LRAM idea, techniques were developed to measure time constants for ion induced voltage transients in conventional static random access memories, SRAM. Time constants of 0.8 and 6.0 nsec were measured for transients following strikes at the n- and p-channel drains, respectively - primary areas of SEU sensitivity. These data are the first transient time measurements on full memory chips and the large difference is fundamental to the LRAM concept. Decoupling resistors in the LRAM are used only to protect against the short transient; longer persisting pulses are blocked by a voltage divider, a basically new concept for SEU protection. In such a design, smaller resistors provide SEU tolerance, allowing higher performance, hardened memories. Test structures of the new design exhibit SEU tolerance with resistors 5-to-10 times smaller than currently used in SRAM. Our advanced transport-plus-circuit numerical simulations of the SEU process predicted this result and account for the LRAM experiments, as well as a variety of experiments on conventional SRAM. 16 refs., 6 figs., 1 tab.

  12. Effect of embedded metal nanocrystals on the resistive switching characteristics in NiN-based resistive random access memory cells

    SciTech Connect

    Yun, Min Ju; Kim, Hee-Dong; Man Hong, Seok; Hyun Park, Ju; Su Jeon, Dong; Geun Kim, Tae

    2014-03-07

    The metal nanocrystals (NCs) embedded-NiN-based resistive random access memory cells are demonstrated using several metal NCs (i.e., Pt, Ni, and Ti) with different physical parameters in order to investigate the metal NC's dependence on resistive switching (RS) characteristics. First, depending on the electronegativity of metal, the size of metal NCs is determined and this affects the operating current of memory cells. If metal NCs with high electronegativity are incorporated, the size of the NCs is reduced; hence, the operating current is reduced owing to the reduced density of the electric field around the metal NCs. Second, the potential wells are formed by the difference of work function between the metal NCs and active layer, and the barrier height of the potential wells affects the level of operating voltage as well as the conduction mechanism of metal NCs embedded memory cells. Therefore, by understanding these correlations between the active layer and embedded metal NCs, we can optimize the RS properties of metal NCs embedded memory cells as well as predict their conduction mechanisms.

  13. Resistive switching characteristics of ZnO thin film grown on stainless steel for flexible nonvolatile memory devices

    SciTech Connect

    Lee, Seunghyup; Kim, Heejin; Yong, Kijung; Yun, Dong-Jin; Rhee, Shi-Woo

    2009-12-28

    This paper reports a resistive switching device of Au/ZnO/stainless steel (SS) and its applicability as a flexible resistive random access memory (ReRAM). The Au/ZnO/SS structure was fabricated by radio frequency sputtering deposition of a ZnO thin film on the SS substrate. The fabricated device showed stable unipolar and bipolar resistive switching behaviors with reliable switching responses over 100 cycles. The device performance was not degraded upon bending, which indicates high potential for flexible ReRAM applications.

  14. Set statistics in conductive bridge random access memory device with Cu/HfO{sub 2}/Pt structure

    SciTech Connect

    Zhang, Meiyun; Long, Shibing Wang, Guoming; Xu, Xiaoxin; Li, Yang; Liu, Qi; Lv, Hangbing; Liu, Ming; Lian, Xiaojuan; Miranda, Enrique; Suñé, Jordi

    2014-11-10

    The switching parameter variation of resistive switching memory is one of the most important challenges in its application. In this letter, we have studied the set statistics of conductive bridge random access memory with a Cu/HfO{sub 2}/Pt structure. The experimental distributions of the set parameters in several off resistance ranges are shown to nicely fit a Weibull model. The Weibull slopes of the set voltage and current increase and decrease logarithmically with off resistance, respectively. This experimental behavior is perfectly captured by a Monte Carlo simulator based on the cell-based set voltage statistics model and the Quantum Point Contact electron transport model. Our work provides indications for the improvement of the switching uniformity.

  15. Research and Applications Modules (RAM), phase B study

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The research and applications modules (RAM) system is discussed. The RAM is a family of payload carrier modules that can be delivered to and retrieved from earth orbit by the space shuttle. The RAM's capability for implementing a wide range of manned and man-tended missions is described. The rams have evolved into three types; (1) pressurized RAMs, (2) unpressurized RAMs, and (3) pressurizable free-flying RAMs. A reference experiment plan for use as a baseline in the derivation and planning of the RAM project is reported. The plan describes the number and frequency of shuttle flights dedicated to RAM missions and the RAM payloads for the identified flights.

  16. HyRAM Testing Script.

    SciTech Connect

    Parkins, Owen

    2014-12-01

    The testing script is to provide a method of inspections to HyRAM (v1.0.0.244 Alpha) application features. This document will lead participants through the use of the application to make sure the application performs as designed. If a feature of the application becomes non-working, this script will relay useful information back to the designers of the application so that the feature can be fixed. This is essential to keep the application updated and performing as designed so that the users of this program can be satisfied. There will be frequent updates of this document to ensure proper testing of future application versions.

  17. Device modeling of ferroelectric memory field-effect transistor for the application of ferroelectric random access memory.

    PubMed

    Lue, Hang-Ting; Wu, Chien-Jang; Tseng, Tseung-Yuen

    2003-01-01

    An improved theoretical analysis on the electrical characteristics of ferroelectric memory field-effect transistor (FeMFET) is given. First, we propose a new analytical expression for the polarization versus electric field (P-E) for the ferroelectric material. It is determined by one parameter and explicitly includes both the saturated and nonsaturated hysteresis loops. Using this expression, we then examine the operational properties for two practical devices such as the metal-ferroelectric-insulator-semiconductor field-effect transistor (MFIS-FET) and metal-ferroelectric-metal-insulator-semiconductor field-effect transistor (MFMIS-FET) as well. A double integral also has been used, in order to include the possible effects due to the nonuniform field and charge distribution along the channel of the device, to calculate the drain current of FeMFET. By using the relevant material parameters close to the (Bi, La)4Ti3O12 (BLT) system, accurate analyses on the capacitors and FeMFET's at various applied biases are made. We also address the issues of depolarization field and retention time about such a device. PMID:12578132

  18. Stream specificity and asymmetries in feature binding and content-addressable access in visual encoding and memory.

    PubMed

    Huynh, Duong L; Tripathy, Srimant P; Bedell, Harold E; Ögmen, Haluk

    2015-01-01

    Human memory is content addressable-i.e., contents of the memory can be accessed using partial information about the bound features of a stored item. In this study, we used a cross-feature cuing technique to examine how the human visual system encodes, binds, and retains information about multiple stimulus features within a set of moving objects. We sought to characterize the roles of three different features (position, color, and direction of motion, the latter two of which are processed preferentially within the ventral and dorsal visual streams, respectively) in the construction and maintenance of object representations. We investigated the extent to which these features are bound together across the following processing stages: during stimulus encoding, sensory (iconic) memory, and visual short-term memory. Whereas all features examined here can serve as cues for addressing content, their effectiveness shows asymmetries and varies according to cue-report pairings and the stage of information processing and storage. Position-based indexing theories predict that position should be more effective as a cue compared to other features. While we found a privileged role for position as a cue at the stimulus-encoding stage, position was not the privileged cue at the sensory and visual short-term memory stages. Instead, the pattern that emerged from our findings is one that mirrors the parallel processing streams in the visual system. This stream-specific binding and cuing effectiveness manifests itself in all three stages of information processing examined here. Finally, we find that the Leaky Flask model proposed in our previous study is applicable to all three features. PMID:26382005

  19. Asymmetric dual-gate-structured one-transistor dynamic random access memory cells for retention characteristics improvement

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    One of the major concerns of one-transistor dynamic random access memory (1T-DRAM) is poor retention time. In this letter, a 1T-DRAM cell with two separated asymmetric gates was fabricated and evaluated to improve sensing margin and retention characteristics. It was observed that significantly enhanced sensing margin and retention time over 1 s were obtained using a negatively biased second gate and trapped electrons in the nitride layer because of increased hole capacity in the floating body. These findings indicate that the proposed device could serve as a promising candidate for overcoming retention issues of 1T-DRAM cells.

  20. Suppression of relaxation effect in HfO2 resistive random access memory array by improved program operations

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Wu, Huaqiang; Gao, Bin; Dai, Lingjun; Deng, Ning; Sekar, Deepak; Lu, Zhichao; Kellam, Mark; Bronner, Gary; Qian, He

    2016-05-01

    As a postprograming resistance shift, the relaxation effect could be a major issue for resistive random access memory (RRAM) applications. To understand the physical mechanisms of the relaxation effect, temperature-related ion and charge movements are analyzed using the incremental-step-pulse program (ISPP) and repeat-cycle program (RCP). Pre-electron detrapping (PED) operation is found to minimize the amount of interfacial trapped charges and thus to greatly reduce the resistance relaxation effect. Our experimental results demonstrate the improved data retention and tight distribution of RRAM arrays as a result of the above optimized program operations.

  1. High-Performance Pattern Placement Metrology on Dynamic Random Access Memory Layers of 0.25 μm Technology

    NASA Astrophysics Data System (ADS)

    Trube, Jutta; Huber, Hans-Ludwig; Bangert, Carola Bläsing-; Rinn, Klaus; Röth, Klaus-Dieter

    1993-12-01

    Pattern placement metrology is a key function in the evaluation of new manufacturing technology and processes. For future dynamic random access memory (DRAM) generations, ground rules of less than 0.25 μm must be achieved. This paper presents the results of an investigation of the Leitz LMS 2020 laser metrology system from Leica for pattern placement metrology for different layers of DRAM and X-ray mask fabrication processes. The results demonstrate clearly that the new Leitz LMS 2020 tool is well suited for pattern placement control of typical CMOS process wafers and X-ray masks with 30 nm accuracy.

  2. Evaluation of Magnetoresistive RAM for Space Applications

    NASA Technical Reports Server (NTRS)

    Heidecker, Jason

    2014-01-01

    Magnetoresistive random-access memory (MRAM) is a non-volatile memory that exploits electronic spin, rather than charge, to store data. Instead of moving charge on and off a floating gate to alter the threshold voltage of a CMOS transistor (creating different bit states), MRAM uses magnetic fields to flip the polarization of a ferromagnetic material thus switching its resistance and bit state. These polarized states are immune to radiation-induced upset, thus making MRAM very attractive for space application. These magnetic memory elements also have infinite data retention and erase/program endurance. Presented here are results of reliability testing of two space-qualified MRAM products from Aeroflex and Honeywell.

  3. Towards scalable parellelism in Monte Carlo particle transport codes using remote memory access

    SciTech Connect

    Romano, Paul K; Brown, Forrest B; Forget, Benoit

    2010-01-01

    One forthcoming challenge in the area of high-performance computing is having the ability to run large-scale problems while coping with less memory per compute node. In this work, they investigate a novel data decomposition method that would allow Monte Carlo transport calculations to be performed on systems with limited memory per compute node. In this method, each compute node remotely retrieves a small set of geometry and cross-section data as needed and remotely accumulates local tallies when crossing the boundary of the local spatial domain. initial results demonstrate that while the method does allow large problems to be run in a memory-limited environment, achieving scalability may be difficult due to inefficiencies in the current implementation of RMA operations.

  4. Memories.

    ERIC Educational Resources Information Center

    Brand, Judith, Ed.

    1998-01-01

    This theme issue of the journal "Exploring" covers the topic of "memories" and describes an exhibition at San Francisco's Exploratorium that ran from May 22, 1998 through January 1999 and that contained over 40 hands-on exhibits, demonstrations, artworks, images, sounds, smells, and tastes that demonstrated and depicted the biological,…

  5. Blackcomb: Hardware-Software Co-design for Non-Volatile Memory in Exascale Systems

    SciTech Connect

    Schreiber, Robert

    2014-11-26

    array [Niu 2012b]. We have conducted an in depth analysis of the circuit and system level design implications of multi-layer cross-point Resistive RAM (MLCReRAM) from performance, power and reliability perspectives [Xu 2013]. The objective of this study is to understand the design trade-offs of this technology with respect to the MLC Phase Change Memory (MLCPCM).Our MLC ReRAM design at the circuit and system levels indicates that different resistance allocation schemes, programming strategies, peripheral designs, and material selections profoundly affect the area, latency, power, and reliability of MLC ReRAM. Based on this analysis, we conduct two case studies: first we compare MLC ReRAM design against MLC phase-change memory (PCM) and multi-layer cross-point ReRAM design, and point out why multi-level ReRAM is appealing; second we further explore the design space for MLC ReRAM. Architecture and Application We explored hybrid checkpointing using phase-change memory for future exascale systems [Dong 2011] and showed that the use of nonvolatile memory for local checkpointing significantly increases the number of faults covered by local checkpoints and reduces the probability of a global failure in the middle of a global checkpoint to less than 1%. We also proposed a technique called i2WAP to mitigate the write variations in NVM-based last-level cache for the improvement of the NVM lifetime [Wang 2013]. Our wear leveling technique attempts to work around the limitations of write endurance by arranging data access so that write operations can be distributed evenly across all the storage cells. During our intensive research on fault-tolerant NVM design, we found that ECC cannot effectively tolerate hard errors from limited write endurance and process imperfection. Therefore, we devised a novel Point and Discard (PAD) architecture in in [ 2012] as a hard-error-tolerant architecture for ReRAM-based Last Level Caches. PAD improves the lifetime of ReRAM caches by 1.6X-440X under

  6. The Aviation Careers Accessibility Program (ACAP) at Florida Memorial College. Final Report.

    ERIC Educational Resources Information Center

    Florida Memorial Coll., Miami.

    This project, referred to as the Aviation Careers Accessibility Program (ACAP) established a model program for inner-city minority high school students that would allow them information and accessibility to careers and opportunities in the aviation industry. The project featured two program components: an academic year component during and a 5- or…

  7. Realization of a reversible switching in TaO{sub 2} polymorphs via Peierls distortion for resistance random access memory

    SciTech Connect

    Zhu, Linggang; Sun, Zhimei; Zhou, Jian; Guo, Zhonglu

    2015-03-02

    Transition-metal-oxide based resistance random access memory (RRAM) is a promising candidate for next-generation universal non-volatile memories. Searching and designing appropriate materials used in the memories becomes an urgent task. Here, a structure with the TaO{sub 2} formula was predicted using evolutionary algorithms in combination with first-principles calculations. This triclinic structure (T-TaO{sub 2}) is both energetically and dynamically more favorable than the commonly believed rutile structure (R-TaO{sub 2}). The metal-insulator transition (MIT) between metallic R-TaO{sub 2} and T-TaO{sub 2} (band gap: 1.0 eV) is via a Peierls distortion, which makes TaO{sub 2} a potential candidate for RRAM. The energy barrier for the reversible phase transition is 0.19 eV/atom and 0.23 eV/atom, respectively, suggesting low power consumption for the resistance switch. The present findings about the MIT as the resistance-switch mechanism in Ta-O system will stimulate experimental work to fabricate tantalum oxides based RRAM.

  8. Magnetoelectric assisted 180° magnetization switching for electric field addressable writing in magnetoresistive random-access memory.

    PubMed

    Wang, Zhiguang; Zhang, Yue; Wang, Yaojin; Li, Yanxi; Luo, Haosu; Li, Jiefang; Viehland, Dwight

    2014-08-26

    Magnetization-based memories, e.g., hard drive and magnetoresistive random-access memory (MRAM), use bistable magnetic domains in patterned nanomagnets for information recording. Electric field (E) tunable magnetic anisotropy can lower the energy barrier between two distinct magnetic states, promising reduced power consumption and increased recording density. However, integration of magnetoelectric heterostructure into MRAM is a highly challenging task owing to the particular architecture requirements of each component. Here, we show an epitaxial growth of self-assembled CoFe2O4 nanostripes with bistable in-plane magnetizations on Pb(Mg,Nb)O3-PbTiO3 (PMN-PT) substrates, where the magnetic switching can be triggered by E-induced elastic strain effect. An unprecedented magnetic coercive field change of up to 600 Oe was observed with increasing E. A near 180° magnetization rotation can be activated by E in the vicinity of the magnetic coercive field. These findings might help to solve the 1/2-selection problem in traditional MRAM by providing reduced magnetic coercive field in E field selected memory cells. PMID:25093903

  9. Perpendicular spin transfer torque magnetic random access memories with high spin torque efficiency and thermal stability for embedded applications (invited)

    NASA Astrophysics Data System (ADS)

    Thomas, Luc; Jan, Guenole; Zhu, Jian; Liu, Huanlong; Lee, Yuan-Jen; Le, Son; Tong, Ru-Ying; Pi, Keyu; Wang, Yu-Jen; Shen, Dongna; He, Renren; Haq, Jesmin; Teng, Jeffrey; Lam, Vinh; Huang, Kenlin; Zhong, Tom; Torng, Terry; Wang, Po-Kang

    2014-05-01

    Magnetic random access memories based on the spin transfer torque phenomenon (STT-MRAMs) have become one of the leading candidates for next generation memory applications. Among the many attractive features of this technology are its potential for high speed and endurance, read signal margin, low power consumption, scalability, and non-volatility. In this paper, we discuss our recent results on perpendicular STT-MRAM stack designs that show STT efficiency higher than 5 kBT/μA, energy barriers higher than 100 kBT at room temperature for sub-40 nm diameter devices, and tunnel magnetoresistance higher than 150%. We use both single device data and results from 8 Mb array to demonstrate data retention sufficient for automotive applications. Moreover, we also demonstrate for the first time thermal stability up to 400 °C exceeding the requirement of Si CMOS back-end processing, thus opening the realm of non-volatile embedded memory to STT-MRAM technology.

  10. The role of the local chemical environment of Ag on the resistive switching mechanism of conductive bridging random access memories.

    PubMed

    Souchier, E; D'Acapito, F; Noé, P; Blaise, P; Bernard, M; Jousseaume, V

    2015-10-01

    Conductive bridging random access memories (CBRAMs) are one of the most promising emerging technologies for the next generation of non-volatile memory. However, the lack of understanding of the switching mechanism at the nanoscale level prevents successful transfer to industry. In this paper, Ag/GeSx/W CBRAM devices are analyzed using depth selective X-ray Absorption Spectroscopy before and after switching. The study of the local environment around Ag atoms in such devices reveals that Ag is in two very distinct environments with short Ag-S bonds due to Ag dissolved in the GeSx matrix, and longer Ag-Ag bonds related to an Ag metallic phase. These experiments allow the conclusion that the switching process involves the formation of metallic Ag nano-filaments initiated at the Ag electrode. All these experimental features are well supported by ab initio molecular dynamics simulations showing that Ag favorably bonds to S atoms, and permit the proposal of a model at the microscopic level that can explain the instability of the conductive state in these Ag-GeSx CBRAM devices. Finally, the principle of the nondestructive method described here can be extended to other types of resistive memory concepts. PMID:26312954

  11. Perpendicular spin transfer torque magnetic random access memories with high spin torque efficiency and thermal stability for embedded applications (invited)

    SciTech Connect

    Thomas, Luc Jan, Guenole; Zhu, Jian; Liu, Huanlong; Lee, Yuan-Jen; Le, Son; Tong, Ru-Ying; Pi, Keyu; Wang, Yu-Jen; Shen, Dongna; He, Renren; Haq, Jesmin; Teng, Jeffrey; Lam, Vinh; Huang, Kenlin; Zhong, Tom; Torng, Terry; Wang, Po-Kang

    2014-05-07

    Magnetic random access memories based on the spin transfer torque phenomenon (STT-MRAMs) have become one of the leading candidates for next generation memory applications. Among the many attractive features of this technology are its potential for high speed and endurance, read signal margin, low power consumption, scalability, and non-volatility. In this paper, we discuss our recent results on perpendicular STT-MRAM stack designs that show STT efficiency higher than 5 k{sub B}T/μA, energy barriers higher than 100 k{sub B}T at room temperature for sub-40 nm diameter devices, and tunnel magnetoresistance higher than 150%. We use both single device data and results from 8 Mb array to demonstrate data retention sufficient for automotive applications. Moreover, we also demonstrate for the first time thermal stability up to 400 °C exceeding the requirement of Si CMOS back-end processing, thus opening the realm of non-volatile embedded memory to STT-MRAM technology.

  12. Realization of a reversible switching in TaO2 polymorphs via Peierls distortion for resistance random access memory

    NASA Astrophysics Data System (ADS)

    Zhu, Linggang; Zhou, Jian; Guo, Zhonglu; Sun, Zhimei

    2015-03-01

    Transition-metal-oxide based resistance random access memory (RRAM) is a promising candidate for next-generation universal non-volatile memories. Searching and designing appropriate materials used in the memories becomes an urgent task. Here, a structure with the TaO2 formula was predicted using evolutionary algorithms in combination with first-principles calculations. This triclinic structure (T-TaO2) is both energetically and dynamically more favorable than the commonly believed rutile structure (R-TaO2). The metal-insulator transition (MIT) between metallic R-TaO2 and T-TaO2 (band gap: 1.0 eV) is via a Peierls distortion, which makes TaO2 a potential candidate for RRAM. The energy barrier for the reversible phase transition is 0.19 eV/atom and 0.23 eV/atom, respectively, suggesting low power consumption for the resistance switch. The present findings about the MIT as the resistance-switch mechanism in Ta-O system will stimulate experimental work to fabricate tantalum oxides based RRAM.

  13. In situ observation of nickel as an oxidizable electrode material for the solid-electrolyte-based resistive random access memory

    SciTech Connect

    Sun, Jun; Wu, Xing; Xu, Feng; Xu, Tao; Sun, Litao; Liu, Qi; Xie, Hongwei; Long, Shibing; Lv, Hangbing; Li, Yingtao; Liu, Ming

    2013-02-04

    In this letter, we dynamically investigate the resistive switching characteristics and physical mechanism of the Ni/ZrO{sub 2}/Pt device. The device shows stable bipolar resistive switching behaviors after forming process, which is similar to the Ag/ZrO{sub 2}/Pt and Cu/ZrO{sub 2}/Pt devices. Using in situ transmission electron microscopy, we observe in real time that several conductive filaments are formed across the ZrO{sub 2} layer between Ni and Pt electrodes after forming. Energy-dispersive X-ray spectroscopy results confirm that Ni is the main composition of the conductive filaments. The ON-state resistance increases with increasing temperature, exhibiting the feature of metallic conduction. In addition, the calculated resistance temperature coefficient is equal to that of the 10-30 nm diameter Ni nanowire, further indicating that the nanoscale Ni conductive bridge is the physical origin of the observed conductive filaments. The resistive switching characteristics and the conductive filament's component of Ni/ZrO{sub 2}/Pt device are consistent with the characteristics of the typical solid-electrolyte-based resistive random access memory. Therefore, aside from Cu and Ag, Ni can also be used as an oxidizable electrode material for resistive random access memory applications.

  14. [Co/Ni]-CoFeB hybrid free layer stack materials for high density magnetic random access memory applications

    NASA Astrophysics Data System (ADS)

    Liu, E.; Swerts, J.; Couet, S.; Mertens, S.; Tomczak, Y.; Lin, T.; Spampinato, V.; Franquet, A.; Van Elshocht, S.; Kar, G.; Furnemont, A.; De Boeck, J.

    2016-03-01

    Alternative free layer materials with high perpendicular anisotropy are researched to provide spin-transfer-torque magnetic random access memory stacks' sufficient thermal stability at critical dimensions of 20 nm and below. We demonstrate a high tunnel magetoresistance (TMR) MgO-based magnetic tunnel junction stack with a hybrid free layer design made of a [Co/Ni] multilayer and CoFeB. The seed material on which the [Co/Ni] multilayer is deposited determines its switching characteristics. When deposited on a Pt seed layer, soft magnetic switching behavior with high squareness is obtained. When deposited on a NiCr seed, the perpendicular anisotropy remains high, but the squareness is low and coercivity exceeds 1000 Oe. Interdiffusion of the seed material with the [Co/Ni] multilayers is found to be responsible for the different switching characteristics. In optimized stacks, a TMR of 165% and low resistance-area (RA) product of 7.0 Ω μm2 are attained for free layers with an effective perpendicular magnetic anisotropy energy of 1.25 erg/cm2, which suggests that the hybrid free layer materials may be a viable candidate for high density magnetic random access memory applications.

  15. Hyperlink Format, Categorization Abilities and Memory Span as Contributors to Deaf Users Hypertext Access

    ERIC Educational Resources Information Center

    Farjardo, Inmaculada; Arfe, Barbara; Benedetti, Patrizia; Altoe, Gianmarco

    2008-01-01

    Sixty deaf and hearing students were asked to search for goods in a Hypertext Supermarket with either graphical or textual links of high typicality, frequency, and familiarity. Additionally, they performed a picture and word categorization task and two working memory span tasks (spatial and verbal). Results showed that deaf students were faster in…

  16. Respecting Relations: Memory Access and Antecedent Retrieval in Incremental Sentence Processing

    ERIC Educational Resources Information Center

    Kush, Dave W.

    2013-01-01

    This dissertation uses the processing of anaphoric relations to probe how linguistic information is encoded in and retrieved from memory during real-time sentence comprehension. More specifically, the dissertation attempts to resolve a tension between the demands of a linguistic processor implemented in a general-purpose cognitive architecture and…

  17. Self-checking on-line testable static RAM

    NASA Technical Reports Server (NTRS)

    Chau, Savio N. (Inventor); Rennels, David A. (Inventor)

    1993-01-01

    This is a fault-tolerant random access memory for use in fault-tolerant computers. It comprises a plurality of memory chips each comprising a plurality of on-line testable and correctable memory cells disposed in rows and columns for holding individually addressable binary bits and provision for error detection incorporated into each memory cell for outputting an error signal whenever a transient error occurs therein. In one embodiment, each of the memory cells comprises a pair of static memory sub-cells for simultaneously receiving and holding a common binary data bit written to the memory cell and the error detection provision comprises comparator logic for continuously sensing and comparing the contents of the memory sub-cells to one another and for outputting the error signal whenever the contents do not match. In another embodiment, each of the memory cells comprises a static memory sub-cell and a dynamic memory sub-cell for simultaneously receiving and holding a common binary data bit written to the memory cell and the error detection provision comprises comparator logic for continuously sensing and comparing the contents of the static memory sub-cell to the dynamic memory sub-cell and for outputting the error signal whenever the contents do not match. Capability for correction of errors is also included.

  18. Integration of Radiation-Hard Magnetic Random Access Memory with CMOS ICs

    SciTech Connect

    Cerjan, C.J.; Sigmon, T.W.

    2000-02-15

    The research undertaken in this LDRD-funded project addressed the joint development of magnetic material-based nonvolatile, radiation-hard memory cells with Sandia National Laboratory. Specifically, the goal of this project was to demonstrate the intrinsic radiation-hardness of Giant Magneto-Resistive (GMR) materials by depositing representative alloy combinations upon radiation-hardened silicon-based integrated circuits. All of the stated goals of the project were achieved successfully. The necessary films were successfully deposited upon typical integrated circuits; the materials retained their magnetic field response at the highest radiation doses; and a patterning approach was developed that did not degrade the as-fabricated properties of the underlying circuitry. These results establish the feasibility of building radiation-hard magnetic memory cells.

  19. On EMDR: eye movements during retrieval reduce subjective vividness and objective memory accessibility during future recall.

    PubMed

    van den Hout, Marcel A; Bartelski, Nicola; Engelhard, Iris M

    2013-01-01

    In eye movement desensitization and reprocessing (EMDR), a treatment for post-traumatic stress disorder (PTSD), patients make eye movements (EM) during trauma recall. Earlier experimental studies found that EM during recall reduces memory vividness during future recalls, and this was taken as laboratory support for the underlying mechanism of EMDR. However, reduced vividness was assessed with self-reports that may be affected by demand characteristics. We tested whether recall+EM also reduces memory vividness on a behavioural reaction time (RT) task. Undergraduates (N=32) encoded two pictures, recalled them, and rated their vividness. In the EM group, one of the pictures was recalled again while making EM. In the no-EM group one of the pictures was recalled without EM. Then fragments from both the recalled and non-recalled pictures, and new fragments were presented and participants rated whether these were (or were not) seen before. Both pictures were rated again for vividness. In the EM group, self-rated vividness of the recalled+EM picture decreased, relative to the non-recalled picture. In the no-EM group there was no difference between the recalled versus non-recalled picture. The RT task showed the same pattern. Reduction of memory vividness due to recall+EM is also evident from non-self-report data. PMID:22765837

  20. An energy-efficient SIMD DSP with multiple VLIW configurations and an advanced memory access unit for LTE-A modem LSIs

    NASA Astrophysics Data System (ADS)

    Tomono, Mitsuru; Ito, Makiko; Nomura, Yoshitaka; Mouri, Makoto; Hirose, Yoshio

    2015-12-01

    Energy efficiency is the most important factor in the design of wireless modem LSIs for mobile handset systems. We have developed an energy-efficient SIMD DSP for LTE-A modem LSIs. Our DSP has mainly two hardware features in order to reduce energy consumption. The first one is multiple VLIW configurations to minimize accesses to instruction memories. The second one is an advanced memory access unit to realize complex memory accesses required for wireless baseband processing. With these features, performance of our DSP is about 1.7 times faster than a base DSP on average for standard LTE-A Libraries. Our DSP achieves about 20% improvement in energy efficiency compared to a base DSP for LTE-A modem LSIs.

  1. An Account of Performance in Accessing Information Stored in Long-Term Memory. A Fixed-Links Model Approach

    ERIC Educational Resources Information Center

    Altmeyer, Michael; Schweizer, Karl; Reiss, Siegbert; Ren, Xuezhu; Schreiner, Michael

    2013-01-01

    Performance in working memory and short-term memory tasks was employed for predicting performance in a long-term memory task in order to find out about the underlying processes. The types of memory were represented by versions of the Posner Task, the Backward Counting Task and the Sternberg Task serving as measures of long-term memory, working…

  2. Improved bipolar resistive switching memory characteristics in Ge0.5Se0.5 solid electrolyte by using dispersed silver nanocrystals on bottom electrode.

    PubMed

    Kim, Jang-Han; Nam, Ki-Hyun; Hwang, Inchan; Cho, Won-Ju; Park, Byoungchoo; Chung, Hong-Bay

    2014-12-01

    Resistive switching random-access memory (ReRAM) devices based on chalcogenide solid electrolytes have recently become a promising candidate for future low-power nanoscale nonvolatile memory application. The resistive switching mechanism of ReRAM is based on the formation and rupture of conductive filament (CF) in the chalcogenide solid electrolyte layers. However, the random diffusion of metal ions makes it hard to control the CF formation, which is one of the major obstacles to improving device performance of ReRAM devices. We demonstrate the spin-coated metal nanocrystals (NCs) enhance the bipolar resistive switching (BRS) memory characteristics. Compared to the Ag/Ge0.5Se0.5/Pt structure, excellent resistive switching memory characteristics were obtained from the Ag/Ge0.5Se0.5/Ag NCs/Pt structure. Ag NCs improve the uniformity of resistance values and reduce the reset voltage and current. A stable DC endurance (> 100 cycles) and a high data retention (> 10(4) sec) were achieved by spin coating the Ag NCs on the Pt bottom electrode for ReRAMs. PMID:25971090

  3. Performance and characteristics of double layer porous silicon oxide resistance random access memory

    NASA Astrophysics Data System (ADS)

    Tsai, Tsung-Ming; Chang, Kuan-Chang; Zhang, Rui; Chang, Ting-Chang; Lou, J. C.; Chen, Jung-Hui; Young, Tai-Fa; Tseng, Bae-Heng; Shih, Chih-Cheng; Pan, Yin-Chih; Chen, Min-Chen; Pan, Jhih-Hong; Syu, Yong-En; Sze, Simon M.

    2013-06-01

    A bilayer resistive switching memory device with an inserted porous silicon oxide layer is investigated in this letter. Compared with single Zr:SiOx layer structure, Zr:SiOx/porous SiOx structure outperforms from various aspects, including low operating voltages, tighter distributions of set voltage, higher stability of both low resistance state and high resistance state, and satisfactory endurance characteristics. Electric field simulation by comsolTM Multiphysics is applied, which corroborates that intensive electric field around the pore in porous SiOx layer guides the conduction of electrons. The constraint of conduction path leads to better stabilization and prominent performance of bilayer resistive switching devices.

  4. An analog random access memory in the AVLSI-RA process for an interpolating pad chamber

    SciTech Connect

    Britton, C.L. Jr.; Wittenberg, A.L.; Read, K.F.; Clonts, L.G.; Kennedy, E.J.; Smith, R.S.; Swann, B.K.; Musser, J.A.

    1995-12-01

    An analog memory for an interpolating pad chamber has been designed at Oak Ridge National Laboratory and fabricated by Harris Semiconductor in the AVLSI-RA CMOS process. The goal was to develop a rad-hard analog pipeline that would deliver approximately 9-b performance, a readout settling time of 500 ns following read enable, an input and output dynamic range of {+-} 2.25 V, a corrected rms pedestal of approximately 5 mV or less, and a power dissipation of less than 10 mW/channel. The pre- and post-radiation measurements to 5 MRad are presented.

  5. 75 FR 16507 - In the Matter of Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-01

    ..., California (``Rambus''). 73 FR 75131-2. The complaint, as amended and supplemented, alleges violations of... Commission's action. See Presidential Memorandum of July 21, 2005, 70 FR 43251 (July 26, 2005). During this... COMMISSION In the Matter of Certain Semiconductor Chips Having Synchronous Dynamic Random Access...

  6. Access to Attitude-Relevant Information in Memory as a Determinant of Attitude-Behavior Consistency.

    ERIC Educational Resources Information Center

    Kallgren, Carl A.; Wood, Wendy

    Recent reserach has attempted to determine systematically how attitudes influence behavior. This research examined whether access to attitude-relevant beliefs and prior experiences would mediate the relation between attitudes and behavior. Subjects were 49 college students with a mean age of 27 who did not live with their parents or in…

  7. Improving Memory after Interruption: Exploiting Soft Constraints and Manipulating Information Access Cost

    ERIC Educational Resources Information Center

    Morgan, Phillip L.; Patrick, John; Waldron, Samuel M.; King, Sophia L.; Patrick, Tanya

    2009-01-01

    Forgetting what one was doing prior to interruption is an everyday problem. The recent soft constraints hypothesis (Gray, Sims, Fu, & Schoelles, 2006) emphasizes the strategic adaptation of information processing strategy to the task environment. It predicts that increasing information access cost (IAC: the time, and physical and mental effort…

  8. A Symptom-Focused Hypnotic Approach to Accessing and Processing Previously Repressed/Dissociated Memories.

    ERIC Educational Resources Information Center

    Ratican, Kathleen L.

    1996-01-01

    The kinesthetic track back technique accesses the origins of current symptoms and may uncover previously repressed/dissociated material, if such material exists in the client's unconscious mind, is relevant to the symptoms, and is ready to be processed consciously. Case examples are given to illustrate proper use of this technique. (LSR)

  9. Fencing network direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOEpatents

    Blocksome, Michael A.; Mamidala, Amith R.

    2015-07-07

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to a deterministic data communications network through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and the deterministic data communications network; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  10. Fencing network direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOEpatents

    Blocksome, Michael A.; Mamidala, Amith R.

    2015-07-14

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to a deterministic data communications network through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and the deterministic data communications network; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  11. Reducing operation current of Ni-doped silicon oxide resistance random access memory by supercritical CO2 fluid treatment

    NASA Astrophysics Data System (ADS)

    Chang, Kuan-Chang; Tsai, Tsung-Ming; Chang, Ting-Chang; Syu, Yong-En; Wang, Chia-C.; Chuang, Siang-Lan; Li, Cheng-Hua; Gan, Der-Shin; Sze, Simon M.

    2011-12-01

    In the study, we reduced the operation current of resistance random access memory (RRAM) by supercritical CO2 (SCCO2) fluids treatment. The power consumption and joule heating degradation of RRAM device can be improved greatly by SCCO2 treatment. The defect of nickel-doped silicon oxide (Ni:SiOx) was passivated effectively by the supercritical fluid technology. The current conduction of high resistant state in post-treated Ni:SiOx film was transferred to Schottky emission from Frenkel-Pool due to the passivation effect. Additionally, we can demonstrate the passivation mechanism of SCCO2 for Ni:SiOx by material analyses of x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy.

  12. Robust Two-Dimensional Stack Capacitor Technologies for 64 Mbit One-Transistor-One-Capacitor Ferroelectric Random Access Memory

    NASA Astrophysics Data System (ADS)

    Jung, Ju-Young; Joo, Heung-Jin; Park, Jung-Hoon; Kang, Seung-Kuk; Kim, Hwi-San; Choi, Do-Yeon; Kim, Jai-Hyun; Lee, Eun-Sun; Hong, Young-Ki; Kim, Hyun-Ho; Jung, Dong-Jin; Kang, Young-Min; Lee, Sung-Yung; Jeong, Hong-Sik; Kim, Kinam

    2007-04-01

    It is very important to develop capacitor module technologies such as robust Pb(ZrxTi1-x)O3 (PZT) film technology at nm scaled PZT thickness and damage minimized ferroelectric capacitor etching technology are crucial for the success of high density one-transistor-one-capacitor (1T1C) ferroelectric random access memory (FRAM). We resolved this issue from the change of the capacitor etching system and optimization of the PZT/SrRuO3 (SRO) deposition process. As a result, we realized a highly reliable sensing window for 64 Mbit 1T1C FRAM that were realized by novel technologies such as robust MOCVD PZT deposition technologies, optimized SRO electrode and damage minimized ferroelectric capacitor etching technologies.

  13. Glprof: A Gprof inspired, Callgraph-oriented Per-Object Disseminating Memory Access Multi-Cache Profiler

    SciTech Connect

    Janjusic, Tommy; Kartsaklis, Christos

    2015-01-01

    Application analysis is facilitated through a number of program profiling tools. The tools vary in their complexity, ease of deployment, design, and profiling detail. Specifically, understand- ing, analyzing, and optimizing is of particular importance for scientific applications where minor changes in code paths and data-structure layout can have profound effects. Understanding how intricate data-structures are accessed and how a given memory system responds is a complex task. In this paper we describe a trace profiling tool, Glprof, specifically aimed to lessen the burden of the programmer to pin-point heavily involved data-structures during an application's run-time, and understand data-structure run-time usage. Moreover, we showcase the tool's modularity using additional cache simulation components. We elaborate on the tool's design, and features. Finally we demonstrate the application of our tool in the context of Spec bench- marks using the Glprof profiler and two concurrently running cache simulators, PPC440 and AMD Interlagos.

  14. Temperature induced complementary switching in titanium oxide resistive random access memory

    NASA Astrophysics Data System (ADS)

    Panda, D.; Simanjuntak, F. M.; Tseng, T.-Y.

    2016-07-01

    On the way towards high memory density and computer performance, a considerable development in energy efficiency represents the foremost aspiration in future information technology. Complementary resistive switch consists of two antiserial resistive switching memory (RRAM) elements and allows for the construction of large passive crossbar arrays by solving the sneak path problem in combination with a drastic reduction of the power consumption. Here we present a titanium oxide based complementary RRAM (CRRAM) device with Pt top and TiN bottom electrode. A subsequent post metal annealing at 400°C induces CRRAM. Forming voltage of 4.3 V is required for this device to initiate switching process. The same device also exhibiting bipolar switching at lower compliance current, Ic <50 μA. The CRRAM device have high reliabilities. Formation of intermediate titanium oxi-nitride layer is confirmed from the cross-sectional HRTEM analysis. The origin of complementary switching mechanism have been discussed with AES, HRTEM analysis and schematic diagram. This paper provides valuable data along with analysis on the origin of CRRAM for the application in nanoscale devices.

  15. Impact of adolescent sucrose access on cognitive control, recognition memory, and parvalbumin immunoreactivity

    PubMed Central

    Killcross, Simon; Hambly, Luke D.; Morris, Margaret J.; Westbrook, R. Fred

    2015-01-01

    In this study we sought to determine the effect of daily sucrose consumption in young rats on their subsequent performance in tasks that involve the prefrontal cortex and hippocampus. High levels of sugar consumption have been associated with the development of obesity, however less is known about how sugar consumption influences behavioral control and high-order cognitive processes. Of particular concern is the fact that sugar intake is greatest in adolescence, an important neurodevelopmental period. We provided sucrose to rats when they were progressing through puberty and adolescence. Cognitive performance was assessed in adulthood on a task related to executive function, a rodent analog of the Stroop task. We found that sucrose-exposed rats failed to show context-appropriate responding during incongruent stimulus compounds presented at test, indicative of impairments in prefrontal cortex function. Sucrose exposed rats also showed deficits in an on object-in-place recognition memory task, indicating that both prefrontal and hippocampal function was impaired. Analysis of brains showed a reduction in expression of parvalbumin-immunoreactive GABAergic interneurons in the hippocampus and prefrontal cortex, indicating that sucrose consumption during adolescence induced long-term pathology, potentially underpinning the cognitive deficits observed. These results suggest that consumption of high levels of sugar-sweetened beverages by adolescents may also impair neurocognitive functions affecting decision-making and memory, potentially rendering them at risk for developing mental health disorders. PMID:25776039

  16. The structure-sensitivity of memory access: evidence from Mandarin Chinese

    PubMed Central

    Dillon, Brian; Chow, Wing-Yee; Wagers, Matthew; Guo, Taomei; Liu, Fengqin; Phillips, Colin

    2014-01-01

    The present study examined the processing of the Mandarin Chinese long-distance reflexive ziji to evaluate the role that syntactic structure plays in the memory retrieval operations that support sentence comprehension. Using the multiple-response speed-accuracy tradeoff (MR-SAT) paradigm, we measured the speed with which comprehenders retrieve an antecedent for ziji. Our experimental materials contrasted sentences where ziji's antecedent was in the local clause with sentences where ziji's antecedent was in a distant clause. Time course results from MR-SAT suggest that ziji dependencies with syntactically distant antecedents are slower to process than syntactically local dependencies. To aid in interpreting the SAT data, we present a formal model of the antecedent retrieval process, and derive quantitative predictions about the time course of antecedent retrieval. The modeling results support the Local Search hypothesis: during syntactic retrieval, comprehenders initially limit memory search to the local syntactic domain. We argue that Local Search hypothesis has important implications for theories of locality effects in sentence comprehension. In particular, our results suggest that not all locality effects may be reduced to the effects of temporal decay and retrieval interference. PMID:25309486

  17. Brain potentials reflect access to visual and emotional memories for faces.

    PubMed

    Bobes, Maria A; Quiñonez, Ileana; Perez, Jhoanna; Leon, Inmaculada; Valdés-Sosa, Mitchell

    2007-05-01

    Familiar faces convey different types of information, unlocking memories related to social-emotional significance. Here, the availability over time of different types of memory was evaluated using the time-course of P3 event related potentials. Two oddball paradigms were employed, both using unfamiliar faces as standards. The infrequent targets were, respectively, artificially-learned faces (devoid of social-emotional content) and faces of acquaintances. Although in both tasks targets were detected accurately, the corresponding time-course and scalp distribution of the P3 responses differed. Artificially-learned and acquaintance faces both elicited a P3b, maximal over centro-parietal sites, and a latency of 500ms. Faces of acquaintances elicited an additional component, an early P3 maximal over frontal sites: with a latency of 350ms. This suggests that visual familiarity can only trigger the overt recognition processes leading to the slower P3b, whereas emotional-social information can also elicit fast and automatic assessments (indexed by the frontal-P3) crucial for successful social interactions. PMID:17350154

  18. ERP evidence for hemispheric asymmetries in exemplar-specific explicit memory access.

    PubMed

    Küper, Kristina; Zimmer, Hubert D

    2015-11-01

    The right cerebral hemisphere (RH) appears to be more effective in representing visual objects as distinct exemplars than the left hemisphere (LH) which is presumably biased towards coding objects at the level of abstract prototypes. As of yet, relatively little is known about the role that asymmetries in exemplar-specificity play at the level of explicit memory retrieval. In the present study, we addressed this issue by examining hemispheric asymmetries in the putative event-related potential (ERP) correlates of familiarity (FN400) and recollection (LPC). In an incidental study phase, pictures of familiar objects were presented centrally. At test, participants performed a memory inclusion task on identical repetitions and different exemplars of study items as well as new items which were presented in only one visual hemifield using the divided visual field technique. With respect to familiarity, we observed exemplar-specific FN400 old/new effects that were more pronounced for identical repetitions than different exemplars, irrespective of the hemisphere governing initial stimulus processing. In contrast, LPC old/new effects were subject to some hemispheric asymmetries indicating that exemplar-specific recollection was more extensive in the RH than in the LH. This further corroborates the idea that hemispheric asymmetries should not be generalized but need to be distinguished not only in different domains but also at different levels of processing. PMID:26279112

  19. Thin Co/Ni-based bottom pinned spin-transfer torque magnetic random access memory stacks with high annealing tolerance

    NASA Astrophysics Data System (ADS)

    Tomczak, Y.; Swerts, J.; Mertens, S.; Lin, T.; Couet, S.; Liu, E.; Sankaran, K.; Pourtois, G.; Kim, W.; Souriau, L.; Van Elshocht, S.; Kar, G.; Furnemont, A.

    2016-01-01

    Spin-transfer torque magnetic random access memory (STT-MRAM) is considered as a replacement for next generation embedded and stand-alone memory applications. One of the main challenges in the STT-MRAM stack development is the compatibility of the stack with CMOS process flows in which thermal budgets up to 400 °C are applied. In this letter, we report on a perpendicularly magnetized MgO-based tunnel junction (p-MTJ) on a thin Co/Ni perpendicular synthetic antiferromagnetic layer with high annealing tolerance. Tunnel magneto resistance (TMR) loss after annealing occurs when the reference layer loses its perpendicular magnetic anisotropy due to reduction of the CoFeB/MgO interfacial anisotropy. A stable Co/Ni based p-MTJ stack with TMR values of 130% at resistance-area products of 9 Ω μm2 after 400 °C anneal is achieved via moment control of the Co/Ta/CoFeB reference layer. Thinning of the CoFeB polarizing layer down to 0.8 nm is the key enabler to achieve 400 °C compatibility with limited TMR loss. Thinning the Co below 0.6 nm leads to a loss of the antiferromagnetic interlayer exchange coupling strength through Ru. Insight into the thickness and moment engineering of the reference layer is displayed to obtain the best magnetic properties and high thermal stability for thin Co/Ni SAF-based STT-MRAM stacks.

  20. Evolution of conductive filament and its impact on reliability issues in oxide-electrolyte based resistive random access memory

    PubMed Central

    Lv, Hangbing; Xu, Xiaoxin; Liu, Hongtao; Liu, Ruoyu; Liu, Qi; Banerjee, Writam; Sun, Haitao; Long, Shibing; Li, Ling; Liu, Ming

    2015-01-01

    The electrochemical metallization cell, also referred to as conductive bridge random access memory, is considered to be a promising candidate or complementary component to the traditional charge based memory. As such, it is receiving additional focus to accelerate the commercialization process. To create a successful mass product, reliability issues must first be rigorously solved. In-depth understanding of the failure behavior of the ECM is essential for performance optimization. Here, we reveal the degradation of high resistance state behaves as the majority cases of the endurance failure of the HfO2 electrolyte based ECM cell. High resolution transmission electron microscopy was used to characterize the change in filament nature after repetitive switching cycles. The result showed that Cu accumulation inside the filament played a dominant role in switching failure, which was further supported by measuring the retention of cycle dependent high resistance state and low resistance state. The clarified physical picture of filament evolution provides a basic understanding of the mechanisms of endurance and retention failure, and the relationship between them. Based on these results, applicable approaches for performance optimization can be implicatively developed, ranging from material tailoring to structure engineering and algorithm design. PMID:25586207

  1. Evolution of conductive filament and its impact on reliability issues in oxide-electrolyte based resistive random access memory.

    PubMed

    Lv, Hangbing; Xu, Xiaoxin; Liu, Hongtao; Liu, Ruoyu; Liu, Qi; Banerjee, Writam; Sun, Haitao; Long, Shibing; Li, Ling; Liu, Ming

    2015-01-01

    The electrochemical metallization cell, also referred to as conductive bridge random access memory, is considered to be a promising candidate or complementary component to the traditional charge based memory. As such, it is receiving additional focus to accelerate the commercialization process. To create a successful mass product, reliability issues must first be rigorously solved. In-depth understanding of the failure behavior of the ECM is essential for performance optimization. Here, we reveal the degradation of high resistance state behaves as the majority cases of the endurance failure of the HfO2 electrolyte based ECM cell. High resolution transmission electron microscopy was used to characterize the change in filament nature after repetitive switching cycles. The result showed that Cu accumulation inside the filament played a dominant role in switching failure, which was further supported by measuring the retention of cycle dependent high resistance state and low resistance state. The clarified physical picture of filament evolution provides a basic understanding of the mechanisms of endurance and retention failure, and the relationship between them. Based on these results, applicable approaches for performance optimization can be implicatively developed, ranging from material tailoring to structure engineering and algorithm design. PMID:25586207

  2. Transient simulation of ram accelerator flowfields

    NASA Astrophysics Data System (ADS)

    Drabczuk, Randall P.; Rolader, G.; Dash, S.; Sinha, N.; York, B.

    1993-01-01

    This paper describes the development of an advanced computational fluid dynamic (CFD) simulation capability in support of the USAF Armament Directorate ram accelerator research initiative. The state-of-the-art CRAFT computer code has been specialized for high fidelity, transient ram accelerator simulations via inclusion of generalized dynamic gridding, solution adaptive grid clustering, and high pressure thermo-chemistry. Selected ram accelerator simulations are presented that serve to exhibit the CRAFT code capabilities and identify some of the principle research/design Issues.

  3. Transient simulation of ram accelerator flowfields

    NASA Astrophysics Data System (ADS)

    Sinha, N.; York, B. J.; Dash, S. M.; Drabczuk, R.; Rolader, G. E.

    1992-10-01

    This paper describes the development of an advanced computational fluid dynamic (CFD) simulation capability in support of the U.S. Air Force Armament Directorate's ram accelerator research initiative. The state-of-the-art CRAFT computer code has been specialized for high fidelity, transient ram accelerator simulations via inclusion of generalized dynamic gridding, solution adaptive grid clustering, high pressure thermochemistry, etc. Selected ram accelerator simulations are presented which serve to exhibit the CRAFT code's capabilities and identify some of the principal research/design issues.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Multilevel metal/Pb(Zr0.52Ti0.48)O3/TiOxNy/Si for next generation FeRAM technology node

    NASA Astrophysics Data System (ADS)

    Sharma, Deepak K.; Khosla, Robin; Sharma, Satinder K.

    2015-09-01

    Metal-Ferroelectric-Insulator-Semiconductor (MFIS) thin film capacitors with lead zirconate titanate (Pb(Zr0.52Ti0.48)O3) as ferroelectric layer and ultrathin high-κ titanium oxynitride (TiOxNy) as insulating buffer layer on p-Si are fabricated by RF magnetron sputtering for non-volatile multilevel ferroelectric random access memory (FeRAM). Micro Raman analysis of the proposed systems confirmed the existence of most stable tetragonal rutile phase in ultrathin TiOxNy and perovskite phase of PZT thin films. AFM analysis showed that surface roughness of ultrathin TiOxNy and thin PZT films are ∼2.54 nm and ∼1.85 nm, respectively and result the uniform interface between substrate and metal. The maximum C-V memory window of ∼1.25 V was obtained at cyclic sweep voltage of ±6 V and starts to decrease when the sweep voltage exceeds 6 V due to charge injection. The fabricated structure possesses good data retention measured till 1.5 h and high, low capacitance states remain distinguishable even if extrapolated to 15 years. The proposed system exhibited excellent TiOxNy-Si interface, incomparable high breakdown field strength ∼11.15 MV/cm and low leakage current density (J) ∼5 μA/cm2 at +4 V. Thus, Au/PZT/TiOxNy/Si MFIS based FeRAM devices with multilevel operation, high breakdown field and excellent retention are prospective contender for next generation multilevel FeRAM technology node.

  6. High performance of graphene oxide-doped silicon oxide-based resistance random access memory

    PubMed Central

    2013-01-01

    In this letter, a double active layer (Zr:SiO x /C:SiO x ) resistive switching memory device with outstanding performance is presented. Through current fitting, hopping conduction mechanism is found in both high-resistance state (HRS) and low-resistance state (LRS) of double active layer RRAM devices. By analyzing Raman and FTIR spectra, we observed that graphene oxide exists in C:SiO x layer. Compared with single Zr:SiO x layer structure, Zr:SiO x /C:SiO x structure has superior performance, including low operating current, improved uniformity in both set and reset processes, and satisfactory endurance characteristics, all of which are attributed to the double-layer structure and the existence of graphene oxide flakes formed by the sputter process. PMID:24261454

  7. The role of the inserted layer in resistive random access memory device

    NASA Astrophysics Data System (ADS)

    Zhang, Dainan; Ma, Guokun; Zhang, Huaiwu; Tang, Xiaoli; Zhong, Zhiyong; Jie, Li; Su, Hua

    2016-07-01

    NiO resistive switching devices were fabricated by reactive DC magnetron sputtering at room temperature containing different inserted layers. From measurements, we demonstrated the filaments were made up by metal Co rather than the oxygen defect or other metal. A current jumping phenomenon in the SET process was observed, evidencing that the filament generating procedure was changed due to the inserted layers. In this process, we demonstrate the current jumping appeared in higher voltage region when the position of inserted layer was close to the bottom electrode. The I–V curves shifted to the positive direction as the thickness of inserted layer increasing. With the change of the number of inserted layers, SET voltages varied while the RESET voltage kept stable. According to the electrochemical metallization memory mechanism, detailed explanations on all the phenomena were addressed. This discovery is supposed of great potentials in the use of designing multi-layer RRAM devices.

  8. High performance of graphene oxide-doped silicon oxide-based resistance random access memory.

    PubMed

    Zhang, Rui; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Chen, Kai-Huang; Lou, Jen-Chung; Chen, Jung-Hui; Young, Tai-Fa; Shih, Chih-Cheng; Yang, Ya-Liang; Pan, Yin-Chih; Chu, Tian-Jian; Huang, Syuan-Yong; Pan, Chih-Hung; Su, Yu-Ting; Syu, Yong-En; Sze, Simon M

    2013-01-01

    In this letter, a double active layer (Zr:SiOx/C:SiOx) resistive switching memory device with outstanding performance is presented. Through current fitting, hopping conduction mechanism is found in both high-resistance state (HRS) and low-resistance state (LRS) of double active layer RRAM devices. By analyzing Raman and FTIR spectra, we observed that graphene oxide exists in C:SiOx layer. Compared with single Zr:SiOx layer structure, Zr:SiOx/C:SiOx structure has superior performance, including low operating current, improved uniformity in both set and reset processes, and satisfactory endurance characteristics, all of which are attributed to the double-layer structure and the existence of graphene oxide flakes formed by the sputter process. PMID:24261454

  9. Access to long-term optical memories using photon echoes retrieved from semiconductor spins

    NASA Astrophysics Data System (ADS)

    Langer, L.; Poltavtsev, S. V.; Yugova, I. A.; Salewski, M.; Yakovlev, D. R.; Karczewski, G.; Wojtowicz, T.; Akimov, I. A.; Bayer, M.

    2014-11-01

    The ability to store optical information is important for both classical and quantum communication. Achieving this in a comprehensive manner (converting the optical field into material excitation, storing this excitation, and releasing it after a controllable time delay) is greatly complicated by the many, often conflicting, properties of the material. More specifically, optical resonances in semiconductor quantum structures with high oscillator strength are inevitably characterized by short excitation lifetimes (and, therefore, short optical memory). Here, we present a new experimental approach to stimulated photon echoes by transferring the information contained in the optical field into a spin system, where it is decoupled from the optical vacuum field and may persist much longer. We demonstrate this for an n-doped CdTe/(Cd,Mg)Te quantum well, the storage time of which could be increased by more than three orders of magnitude, from the picosecond range up to tens of nanoseconds.

  10. Distribution of nanoscale nuclei in the amorphous dome of a phase change random access memory

    SciTech Connect

    Lee, Bong-Sub Darmawikarta, Kristof; Abelson, John R.; Raoux, Simone; Shih, Yen-Hao; Zhu, Yu

    2014-02-17

    The nanoscale crystal nuclei in an amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} bit in a phase change memory device were evaluated by fluctuation transmission electron microscopy. The quench time in the device (∼10 ns) afforded more and larger nuclei in the melt-quenched state than in the as-deposited state. However, nuclei were even more numerous and larger in a test structure with a longer quench time (∼100 ns), verifying the prediction of nucleation theory that slower cooling produces more nuclei. It also demonstrates that the thermal design of devices will strongly influence the population of nuclei, and thus the speed and data retention characteristics.

  11. Ferroelectric HfO2-based materials for next-generation ferroelectric memories

    NASA Astrophysics Data System (ADS)

    Fan, Zhen; Chen, Jingsheng; Wang, John

    2016-05-01

    Ferroelectric random access memory (FeRAM) based on conventional ferroelectric perovskites, such as Pb(Zr,Ti)O3 and SrBi2Ta2O9, has encountered bottlenecks on memory density and cost, because those conventional perovskites suffer from various issues mainly including poor complementary metal-oxide-semiconductor (CMOS)-compatibility and limited scalability. Next-generation cost-efficient, high-density FeRAM shall therefore rely on a material revolution. Since the discovery of ferroelectricity in Si:HfO2 thin films in 2011, HfO2-based materials have aroused widespread interest in the field of FeRAM, because they are CMOS-compatible and can exhibit robust ferroelectricity even when the film thickness is scaled down to below 10 nm. A review on this new class of ferroelectric materials is therefore of great interest. In this paper, the most appealing topics about ferroelectric HfO2-based materials including origins of ferroelectricity, advantageous material properties, and current and potential applications in FeRAM, are briefly reviewed.

  12. Highly reliable switching via phase transition using hydrogen peroxide in homogeneous and multi-layered GaZnO(x)-based resistive random access memory devices.

    PubMed

    Park, Sung Pyo; Yoon, Doo Hyun; Tak, Young Jun; Lee, Heesoo; Kim, Hyun Jae

    2015-06-01

    Here, we propose an effective method for improving the resistive switching characteristics of solution-processed gallium-doped zinc oxide (GaZnO(x)) resistive random access memory (RRAM) devices using hydrogen peroxide. Our results imply that solution processed GaZnO(x) RRAM devices could be one of the candidates for the development of low cost RRAM. PMID:25947353

  13. Robust Three-Metallization Back End of Line Process for 0.18 μm Embedded Ferroelectric Random Access Memory

    NASA Astrophysics Data System (ADS)

    Kang, Seung-Kuk; Rhie, Hyoung-Seub; Kim, Hyun-Ho; Koo, Bon-Jae; Joo, Heung-Jin; Park, Jung-Hun; Kang, Young-Min; Choi, Do-Hyun; Lee, Sung-Young; Jeong, Hong-Sik; Kim, Kinam

    2005-04-01

    We developed ferroelectric random access memory (FRAM)-embedded smartcards in which FRAM replaces electrically erasable PROM (EEPROM) and static random access memory (SRAM) to improve the read/write cycle time and endurance of data memories during operation, in which the main time delay retardation observed in EEPROM embedded smartcards occurs because of slow data update time. EEPROM-embedded smartcards have EEPROM, ROM, and SRAM. To utilize FRAM-embedded smartcards, we should integrate submicron ferroelectric capacitors into embedded logic complementary metal oxide semiconductor (CMOS) without the degradation of the ferroelectric properties. We resolved this process issue from the viewpoint of the back end of line (BEOL) process. As a result, we realized a highly reliable sensing window for FRAM-embedded smartcards that were realized by novel integration schemes such as tungsten and barrier metal (BM) technology, multilevel encapsulating (EBL) layer scheme and optimized intermetallic dielectrics (IMD) technology.

  14. Ram Pressure Stripping: The Long Goodbye

    NASA Astrophysics Data System (ADS)

    Tonnesen, Stephanie; Lu, Yu; Benson, Andrew; Peter, Annika; Boylan-Kolchin, Michael; Wetzel, Andrew R.; Weisz, Daniel R.

    2016-01-01

    What turns off star formation in satellite galaxies? Ram pressure stripping, the removal of a galaxy's gas through direct interaction with the gas halo in which it orbits, is an attractive quenching mechanism, particularly in the Milky Way halo where the radial distribution of quenching is dramatic. However, many implementations of this process in semi-analytic models result in overly-rapid gas removal when compared with observations. We use high resolution hydrodynamical simulations run with Enzo to parameterize the stripping of disk and halo gas from an orbiting satellite galaxy for use in the semi-analytic modeling code Galacticus. We find that using the instantaneous ram pressure overestimates the amount of gas that is stripped, and present a physically-motivated module for including ram pressure stripping in semi-analytic models that uses the integral of the ram pressure experienced by a satellite galaxy. We will compare our results to observations of the Milky Way satellites.

  15. Distinct Effects of Memory Retrieval and Articulatory Preparation when Learning and Accessing New Word Forms

    PubMed Central

    Nora, Anni; Renvall, Hanna; Kim, Jeong-Young; Service, Elisabet; Salmelin, Riitta

    2015-01-01

    Temporal and frontal activations have been implicated in learning of novel word forms, but their specific roles remain poorly understood. The present magnetoencephalography (MEG) study examines the roles of these areas in processing newly-established word form representations. The cortical effects related to acquiring new phonological word forms during incidental learning were localized. Participants listened to and repeated back new word form stimuli that adhered to native phonology (Finnish pseudowords) or were foreign (Korean words), with a subset of the stimuli recurring four times. Subsequently, a modified 1-back task and a recognition task addressed whether the activations modulated by learning were related to planning for overt articulation, while parametrically added noise probed reliance on developing memory representations during effortful perception. Learning resulted in decreased left superior temporal and increased bilateral frontal premotor activation for familiar compared to new items. The left temporal learning effect persisted in all tasks and was strongest when stimuli were embedded in intermediate noise. In the noisy conditions, native phonotactics evoked overall enhanced left temporal activation. In contrast, the frontal learning effects were present only in conditions requiring overt repetition and were more pronounced for the foreign language. The results indicate a functional dissociation between temporal and frontal activations in learning new phonological word forms: the left superior temporal responses reflect activation of newly-established word-form representations, also during degraded sensory input, whereas the frontal premotor effects are related to planning for articulation and are not preserved in noise. PMID:25961571

  16. Array-level stability enhancement of 50 nm AlxOy ReRAM

    NASA Astrophysics Data System (ADS)

    Iwasaki, Tomoko Ogura; Ning, Sheyang; Yamazawa, Hiroki; Takeuchi, Ken

    2015-12-01

    ReRAM's low voltage and low current programmability are attractive features to solve the scaling issues of conventional floating gate Flash. However, read instability in ReRAM is a critical issue, due to random telegraph noise (RTN), sensitivity to disturb and retention. In this work, the array-level characteristics of read stability in 50 nm AlxOy ReRAM are investigated and a circuit technique to improve stability is proposed and evaluated. First, in order to quantitatively assess memory cell stability, a method of stability characterization is defined. Next, based on this methodology, a proposal to improve read stability, called "stability check loop" is evaluated. The stability check loop is a stability verification procedure, by which, instability improvement of 7×, and read error rate improvement of 40% are obtained.

  17. HyRAM Testing Strategy and Quality Design Elements.

    SciTech Connect

    Reynolds, John Thomas

    2014-12-01

    Strategy document and tentative schedule for testing of HyRAM, a software toolkit that integrates data and methods relevant to assessing the safety of hydrogen fueling and storage infrastructure. Because proposed and existing features in HyRAM that support testing are important factors in this discussion, relevant design considerations of HyRAM are also discussed. However, t his document does not cover all of HyRAM desig n, nor is the full HyRAM software development schedule included.

  18. Experiment of rocket-ram annular combustor

    NASA Astrophysics Data System (ADS)

    Yatsuyanagi, Nobuyuki; Sakamoto, Hiroshi; Sato, Kazuo; Sasaki, Masaki; Ono, Fumiei

    Superiority in specific impulse of the double-nozzle type of rocket-ram combined engine over the ducted type of combined engine was shown by performance calculations. Then, a double-nozzle type of rocket-ram annular combustor with a total thrust of 5 kN was designed and experimentally tested with varying ratios of thrust produced by rocket and ram. With the combustor having different diverging half-angles, namely 10 deg 18 arcmin, and 6 deg 40 arcmin, thrust and pressure distribution along the common expansion nozzle were measured to investigate the effect of interaction of the two expansion gases on thrust. Enhancement of specific impulse was experimentally verified. That is, the specific impulse gained in rocket-ram parallel operations, the ratio of rocket thrust to ram thrust being 50 to 50, were found to be 190 percent of those in pure rocket operations. However, in the downstream region of the common nozzle, the flow might separate due to the generation of shock waves in either type of nozzle configuration.

  19. Solar particle induced upsets in the TDRS-1 attitude control system RAM during the October 1989 solar particle events

    SciTech Connect

    Croley, D.R.; Garrett, H.B.; Murphy, G.B.; Garrard, T.L.

    1995-10-01

    The three large solar particle events, beginning on October 19, 1989 and lasting approximately six days, were characterized by high fluences of solar protons and heavy ions at 1 AU. During these events, an abnormally large number of upsets (243) were observed in the random access memory of the attitude control system (ACS) control processing electronics (CPE) on-board the geosynchronous TDRS-1 (Telemetry and Data Relay Satellite). The RAM unit affected was composed of eight Fairchild 93L422 memory chips. The Galileo spacecraft, launched on October 18, 1989 (one day prior to the solar particle events) observed the fluxes of heavy ions experienced by TDRS-1. Two solid-state detector telescopes on-board Galileo, designed to measure heavy ion species and energy, were turned on during time periods within each of the three separate events. The heavy ion data have been modeled and the time history of the events reconstructed to estimate heavy ion fluences. These fluences were converted to effective LET spectra after transport through the estimated shielding distribution around the TDRS-1 ACS system. The number of single event upsets (SEU) expected was calculated by integrating the measured cross section for the Fairchild 93L422 memory chip with average effective LET spectrum. The expected number of heavy ion induced SEU`s calculated was 176. GOES-7 proton data, observed during the solar particle events, were used to estimate the number of proton-induced SEU`s by integrating the proton fluence spectrum incident on the memory chips, with the two-parameter Bendel cross section for proton SEU`s. The proton fluence spectrum at the device level was gotten by transporting the protons through the estimated shielding distribution. The number of calculated proton-induced SEU`s was 72, yielding a total of 248 predicted SEU`s, very close to the 243 observed SEU`s.

  20. Solar Particle Induced Upsets in the TDRS-1 Attitude Control System RAM During the October 1989 Solar Particle Events

    NASA Technical Reports Server (NTRS)

    Croley, D. R.; Garrett, H. B.; Murphy, G. B.; Garrard,T. L.

    1995-01-01

    The three large solar particle events, beginning on October 19, 1989 and lasting approximately six days, were characterized by high fluences of solar protons and heavy ions at 1 AU. During these events, an abnormally large number of upsets (243) were observed in the random access memory of the attitude control system (ACS) control processing electronics (CPE) on-board the geosynchronous TDRS-1 (Telemetry and Data Relay Satellite). The RAM unit affected was composed of eight Fairchild 93L422 memory chips. The Galileo spacecraft, launched on October 18, 1989 (one day prior to the solar particle events) observed the fluxes of heavy ions experienced by TDRS-1. Two solid-state detector telescopes on-board Galileo, designed to measure heavy ion species and energy, were turned on during time periods within each of the three separate events. The heavy ion data have been modeled and the time history of the events reconstructed to estimate heavy ion fluences. These fluences were converted to effective LET spectra after transport through the estimated shielding distribution around the TDRS-1 ACS system. The number of single event upsets (SEU) expected was calculated by integrating the measured cross section for the Fairchild 93L422 memory chip with average effective LET spectrum. The expected number of heavy ion induced SEU's calculated was 176. GOES-7 proton data, observed during the solar particle events, were used to estimate the number of proton-induced SEU's by integrating the proton fluence spectrum incident on the memory chips, with the two-parameter Bendel cross section for proton SEU'S. The proton fluence spectrum at the device level was gotten by transporting the protons through the estimated shielding distribution. The number of calculated proton-induced SEU's was 72, yielding a total of 248 predicted SEU'S, very dose to the 243 observed SEU'S. These calculations uniquely demonstrate the roles that solar heavy ions and protons played in the production of SEU

  1. A 0.5-V Six-Transistor Static Random Access Memory with Ferroelectric-Gate Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Tanakamaru, Shuhei; Hatanaka, Teruyoshi; Yajima, Ryoji; Miyaji, Kousuke; Takahashi, Mitsue; Sakai, Shigeki; Takeuchi, Ken

    2010-12-01

    A 0.5 V six-transistor static random access memory (6T-SRAM) with ferroelectric-gate field-effect-transistors (Fe-FETs) is proposed and experimentally demonstrated for the first time. During the read and the hold, the threshold voltage (VTH) of Fe-FETs automatically changes to increase the static noise margin (SNM) by 60%. During the stand-by, the VTH of the proposed SRAM cell increases to decrease the leakage current by 42%. In case of the read, the VTH of the read transistor decreases and increases the cell read current to achieve the fast read. During the write, the VTH of the SRAM cell dynamically changes and assist the cell data to flip, realizing a write assist function. The enlarged SNM realizes the VDD reduction by 0.11 V, which decreases the active power by 32%. The proposed SRAM layout is the same as the conventional 6T-SRAM and there is no area penalty.

  2. Resistance switching behavior of ZnO resistive random access memory with a reduced graphene oxide capping layer

    NASA Astrophysics Data System (ADS)

    Lin, Cheng-Li; Chang, Wei-Yi; Huang, Yen-Lun; Juan, Pi-Chun; Wang, Tse-Wen; Hung, Ke-Yu; Hsieh, Cheng-Yu; Kang, Tsung-Kuei; Shi, Jen-Bin

    2015-04-01

    In this work, we investigate the characteristics of ZnO resistive random access memory (RRAM) with a reduced graphene oxide (rGO) capping layer and the polarity effect of the SET/RESET bias on the RRAM. The rGO film insertion enhances the stability of the current-voltage (I-V) switching curve and the superior resistance ratio (˜105) of high-resistance state (HRS) to low-resistance state (LRS). Using the appropriate polarity of the SET/RESET bias applied to the rGO-capped ZnO RRAM enables the oxygen ions to move mainly at the interface of the rGO and ZnO films, resulting in the best performance. Presumably, the rGO film acts as an oxygen reservoir and enhances the easy in and out motion of the oxygen ions from the rGO film. The rGO film also prevents the interaction of oxygen ions and the Al electrode, resulting in excellent performance. In a pulse endurance test, the rGO-capped ZnO RRAM reveals superior endurance of up to 108 cycles over that of the ZnO RRAM without rGO insertion (106 cycles).

  3. Effects of different dopants on switching behavior of HfO2-based resistive random access memory

    NASA Astrophysics Data System (ADS)

    Deng, Ning; Pang, Hua; Wu, Wei

    2014-10-01

    In this study the effects of doping atoms (Al, Cu, and N) with different electro-negativities and ionic radii on resistive switching of HfO2-based resistive random access memory (RRAM) are systematically investigated. The results show that forming voltages and set voltages of Al/Cu-doped devices are reduced. Among all devices, Cu-doped device shows the narrowest device-to-device distributions of set voltage and low resistance. The effects of different dopants on switching behavior are explained with deferent types of CFs formed in HfO2 depending on dopants: oxygen vacancy (Vo) filaments for Al-doped HfO2 devices, hybrid filaments composed of oxygen vacancies and Cu atoms for Cu-doped HfO2 devices, and nitrogen/oxygen vacancy filaments for N-doped HfO2 devices. The results suggest that a metal dopant with a larger electro-negativity than host metal atom offers the best comprehensive performance.

  4. Cu impurity in insulators and in metal-insulator-metal structures: Implications for resistance-switching random access memories

    SciTech Connect

    Pandey, Sumeet C. Meade, Roy; Sandhu, Gurtej S.

    2015-02-07

    We present numerical results from atomistic simulations of Cu in SiO{sub 2} and Al{sub 2}O{sub 3}, with an emphasis on the thermodynamic, kinetic, and electronic properties. The calculated properties of Cu impurity at various concentrations (9.91 × 10{sup 20 }cm{sup −3} and 3.41 × 10{sup 22 }cm{sup −3}) in bulk oxides are presented. The metal-insulator interfaces result in up to a ∼4 eV reduction in the formation energies relative to the crystalline bulk. Additionally, the importance of Cu-Cu interaction in lowering the chemical potential is introduced. These concepts are then discussed in the context of formation and stability of localized conductive paths in resistance-switching Random Access Memories (RRAM-M). The electronic density of states and non-equilibrium transmission through these localized paths are studied, confirming conduction by showing three orders of magnitude increase in the electron transmission. The dynamic behavior of the conductive paths is investigated with atomistic drift-diffusion calculations. Finally, the paper concludes with a molecular dynamics simulation of a RRAM-M cell that attempts to combine the aforementioned phenomena in one self-consistent model.

  5. Low leakage ZrO2 based capacitors for sub 20 nm dynamic random access memory technology nodes

    NASA Astrophysics Data System (ADS)

    Pešić, Milan; Knebel, Steve; Geyer, Maximilian; Schmelzer, Sebastian; Böttger, Ulrich; Kolomiiets, Nadiia; Afanas'ev, Valeri V.; Cho, Kyuho; Jung, Changhwa; Chang, Jaewan; Lim, Hanjin; Mikolajick, Thomas; Schroeder, Uwe

    2016-02-01

    During dynamic random access memory (DRAM) capacitor scaling, a lot of effort was put searching for new material stacks to overcome the scaling limitations of the current material stack, such as leakage and sufficient capacitance. In this study, very promising results for a SrTiO3 based capacitor with a record low capacitance equivalent thickness value of 0.2 nm at target leakage current are presented. Due to the material properties of SrTiO3 films (high vacancy concentration and low band gap), which are leading to an increased leakage current, a physical thickness of at least 8 nm is required at target leakage specifications. However, this physical thickness would not fit into an 18 nm DRAM structure. Therefore, two different new approaches to develop a new ZrO2 based DRAM capacitor stack by changing the inter-layer material from Al2O3 to SrO and the exchange of the top electrode material from TiN to Pt are presented. A combination of these two approaches leads to a capacitance equivalent thickness value of 0.47 nm. Most importantly, the physical thickness of <5 nm for the dielectric stack is in accordance with the target specifications. Detailed evaluation of the leakage current characteristics leads to a capacitor model which allows the prediction of the electrical behavior with thickness scaling.

  6. A Characterization of Endurance in 64 Mbit Ferroelectric Random Access Memory by Analyzing the Space Charge Concentration

    NASA Astrophysics Data System (ADS)

    Lee, Eun Sun; Jung, Dong Jin; Kang, Young Min; Kim, Hyun Ho; Hong, Young Ki; Park, Jung Hoon; Kuk Kang, Seung; Kim, Jae Hyun; San Kim, Hee; Jung, Won Woong; Ahn, Woo Song; Jung, Ju Young; Kang, Jin Young; Choi, Do Yeon; Goh, Han Kyung; Kim, Song Yi; Lee, Sang Young; Jeong, Hong Sik

    2008-04-01

    Space charge concentration due to fatigue cycles was examined with an adequate modeling in order to expect read/write endurance of a 64 Mbit one-transistor and one-capacitor (1T1C) ferroelectric random access memory (FRAM). For monitoring the change in space charge concentration according to fatigue cycles, we assumed that our ferroelectric capacitor is governed by a partially depleted Schottky conduction model. With this, the space charge concentration at the each decade of the fatigue cycles was calculated by measuring the current-voltage characteristics. The space charge concentration at the initial stage was evaluated into 1.95 ×1020 and 2.16 ×1020/cm3 after the 1011 cycles. The concentration of 2.29 ×1020/cm3 was expected at the fatigue cycles of 1016 through a linear regression of the concentration plot against fatigue cycles. Accordingly, it could be said that our ferroelectric capacitor has few problems of endurance up to the 1016 cycles considering the concentration of ˜1020 and the film thickness of 80 nm. Other empirical data obtained in the capacitor level after full integration are supporting this expectation as well.

  7. Switching characteristics for ferroelectric random access memory based on RC model in poly(vinylidene fluoride-trifluoroethylene) ultrathin films

    NASA Astrophysics Data System (ADS)

    Liu, ChangLi; Wang, XueJun; Zhang, XiuLi; Du, XiaoLi; Xu, HaiSheng

    2016-05-01

    The switching characteristic of the poly(vinylidene fluoride-trifluoroethlene) (P(VDF-TrFE)) films have been studied at different ranges of applied electric field. It is suggest that the increase of the switching speed upon nucleation protocol and the deceleration of switching could be related to the presence of a non-ferroelectric layer. Remarkably, a capacitor and resistor (RC) links model plays significant roles in the polarization switching dynamics of the thin films. For P(VDF-TrFE) ultrathin films with electroactive interlayer, it is found that the switching dynamic characteristics are strongly affected by the contributions of resistor and non-ferroelectric (non-FE) interface factors. A corresponding experiment is designed using poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic) (PEDOT-PSSH) as interlayer with different proton concentrations, and the testing results show that the robust switching is determined by the proton concentration in interlayer and lower leakage current in circuit to reliable applications of such polymer films. These findings provide a new feasible method to enhance the polarization switching for the ferroelectric random access memory.

  8. Energetics of intrinsic defects in NiO and the consequences for its resistive random access memory performance

    NASA Astrophysics Data System (ADS)

    Dawson, J. A.; Guo, Y.; Robertson, J.

    2015-09-01

    Energetics for a variety of intrinsic defects in NiO are calculated using state-of-the-art ab initio hybrid density functional theory calculations. At the O-rich limit, Ni vacancies are the lowest cost defect for all Fermi energies within the gap, in agreement with the well-known p-type behaviour of NiO. However, the ability of the metal electrode in a resistive random access memory metal-oxide-metal setup to shift the oxygen chemical potential towards the O-poor limit results in unusual NiO behaviour and O vacancies dominating at lower Fermi energy levels. Calculated band diagrams show that O vacancies in NiO are positively charged at the operating Fermi energy giving it the advantage of not requiring a scavenger metal layer to maximise drift. Ni and O interstitials are generally found to be higher in energy than the respective vacancies suggesting that significant recombination of O vacancies and interstitials does not take place as proposed in some models of switching behaviour.

  9. Energetics of intrinsic defects in NiO and the consequences for its resistive random access memory performance

    SciTech Connect

    Dawson, J. A. Guo, Y.; Robertson, J.

    2015-09-21

    Energetics for a variety of intrinsic defects in NiO are calculated using state-of-the-art ab initio hybrid density functional theory calculations. At the O-rich limit, Ni vacancies are the lowest cost defect for all Fermi energies within the gap, in agreement with the well-known p-type behaviour of NiO. However, the ability of the metal electrode in a resistive random access memory metal-oxide-metal setup to shift the oxygen chemical potential towards the O-poor limit results in unusual NiO behaviour and O vacancies dominating at lower Fermi energy levels. Calculated band diagrams show that O vacancies in NiO are positively charged at the operating Fermi energy giving it the advantage of not requiring a scavenger metal layer to maximise drift. Ni and O interstitials are generally found to be higher in energy than the respective vacancies suggesting that significant recombination of O vacancies and interstitials does not take place as proposed in some models of switching behaviour.

  10. Vividness of Visual Imagery and Incidental Recall of Verbal Cues, When Phenomenological Availability Reflects Long-Term Memory Accessibility

    PubMed Central

    D’Angiulli, Amedeo; Runge, Matthew; Faulkner, Andrew; Zakizadeh, Jila; Chan, Aldrich; Morcos, Selvana

    2013-01-01

    The relationship between vivid visual mental images and unexpected recall (incidental recall) was replicated, refined, and extended. In Experiment 1, participants were asked to generate mental images from imagery-evoking verbal cues (controlled on several verbal properties) and then, on a trial-by-trial basis, rate the vividness of their images; 30 min later, participants were surprised with a task requiring free recall of the cues. Higher vividness ratings predicted better incidental recall of the cues than individual differences (whose effect was modest). Distributional analysis of image latencies through ex-Gaussian modeling showed an inverse relation between vividness and latency. However, recall was unrelated to image latency. The follow-up Experiment 2 showed that the processes underlying trial-by-trial vividness ratings are unrelated to the Vividness of Visual Imagery Questionnaire (VVIQ), as further supported by a meta-analysis of a randomly selected sample of relevant literature. The present findings suggest that vividness may act as an index of availability of long-term sensory traces, playing a non-epiphenomenal role in facilitating the access of those memories. PMID:23382719

  11. Calculation of energy-barrier lowering by incoherent switching in spin-transfer torque magnetoresistive random-access memory

    SciTech Connect

    Munira, Kamaram; Visscher, P. B.

    2015-05-07

    To make a useful spin-transfer torque magnetoresistive random-access memory (STT-MRAM) device, it is necessary to be able to calculate switching rates, which determine the error rates of the device. In a single-macrospin model, one can use a Fokker-Planck equation to obtain a low-current thermally activated rate ∝exp(−E{sub eff}/k{sub B}T). Here, the effective energy barrier E{sub eff} scales with the single-macrospin energy barrier KV, where K is the effective anisotropy energy density and V the volume. A long-standing paradox in this field is that the actual energy barrier appears to be much smaller than this. It has been suggested that incoherent motions may lower the barrier, but this has proved difficult to quantify. In the present paper, we show that the coherent precession has a magnetostatic instability, which allows quantitative estimation of the energy barrier and may resolve the paradox.

  12. Recurrent 3-day cycles of water deprivation for over a month depress mating behaviour but not semen characteristics of adult rams.

    PubMed

    Khnissi, S; Lassoued, N; Rekik, M; Ben Salem, H

    2016-02-01

    This study aimed to investigate the effect of water deprivation (WD) on reproductive traits of rams. Ten mature rams were used and allocated to two groups balanced for body weight. Control (C) rams had free access to drinking water, while water-restricted rams (WD) were deprived from water for 3 consecutive days and early on the morning of day 4, they had ad libitum access to water for 24 h, similar to C animals. The experiment lasted 32 days, that is eight 4-day cycles of water deprivation and subsequent watering. Feed and water intake were significantly affected by water deprivation; in comparison with C rams, WD rams reduced their feed intake by 18%. During the watering day of the deprivation cycle, WD rams consumed more water than C rams on the same day (11.8 (SD = 3.37) and 8.4 (SD = 1.92) l respectively; p < 0.05). Glucose, total protein and creatinine were increased as a result of water deprivation. However, testosterone levels were lowered as a result of water deprivation and average values were 10.9 and 6.2 (SEM 1.23) ng/ml for C and WD rams respectively (p < 0.05). Semen traits were less affected by treatment; WD rams consistently had superior sperm concentrations than C animals; and statistical significances were reached in cycles 5 and 8 of water deprivation. Several mating behaviour traits were modified as a result of water deprivation. When compared to controls, WD rams had a more prolonged time to first mount attempt (p < 0.001), their frequency of mount attempts decreased [6.8 vs. 5.2 (SEM 0.1); p < 0.001] and their flehmen reaction intensity was negatively affected (p < 0.05). Water deprivation may have practical implications reducing the libido and therefore the serving capacity of rams under field conditions. PMID:25916259

  13. Anxious uncertainty and reactive approach motivation (RAM).

    PubMed

    McGregor, Ian; Nash, Kyle; Mann, Nikki; Phills, Curtis E

    2010-07-01

    In 4 experiments anxious uncertainty threats caused reactive approach motivation (RAM). In Studies 1 and 2, academic anxious uncertainty threats caused RAM as assessed by behavioral neuroscience and implicit measures of approach motivation. In Study 3 the effect of a relational anxious uncertainty threat on approach-motivated personal projects in participants' everyday lives was mediated by the idealism of those projects. In Study 4 the effect of a different relational anxious uncertainty threat on implicit approach motivation was heightened by manipulated salience of personal ideals. Results suggest a RAM account for idealistic and ideological reactions in the threat and defense literature. Speculative implications are suggested for understanding diverse social and clinical phenomena ranging from worldview defense, prejudice, and meaning making to narcissism, hypomania, and aggression. PMID:20565191

  14. Reactive approach motivation (RAM) for religion.

    PubMed

    McGregor, Ian; Nash, Kyle; Prentice, Mike

    2010-07-01

    In 3 experiments, participants reacted with religious zeal to anxious uncertainty threats that have caused reactive approach motivation (RAM) in past research (see McGregor, Nash, Mann, & Phills, 2010, for implicit, explicit, and neural evidence of RAM). In Study 1, results were specific to religious ideals and did not extend to merely superstitious beliefs. Effects were most pronounced among the most anxious and uncertainty-averse participants in Study 1 and among the most approach-motivated participants in Study 2 (i.e., with high Promotion Focus, Behavioral Activation, Action Orientation, and Self-Esteem Scale scores). In Studies 2 and 3, anxious uncertainty threats amplified even the most jingoistic and extreme aspects of religious zeal. In Study 3, reactive religious zeal occurred only among participants who reported feeling disempowered in their everyday goals in life. Results support a RAM view of empowered religious idealism for anxiety management (cf. Armstrong, 2000; Inzlicht, McGregor, Hirsch, & Nash, 2009). PMID:20565192

  15. /TiN Resistive RAM (RRAM) Cells

    NASA Astrophysics Data System (ADS)

    Chen, Z. X.; Fang, Z.; Wang, Y.; Yang, Y.; Kamath, A.; Wang, X. P.; Singh, N.; Lo, G.-Q.; Kwong, D.-L.; Wu, Y. H.

    2014-11-01

    We present a study of Ni silicide as the bottom electrode in HfO2-based resistive random-access memory cells. Various silicidation conditions were used for each device, yielding different Ni concentrations within the electrode. A higher concentration of Ni in the bottom electrode was found to cause a parasitic SET operation during certain RESET operation cycles, being attributed to field-assisted Ni cation migration creating a Ni filament. As such, the RESET is affected unless an appropriate RESET voltage is used. Bottom electrodes with lower concentrations of Ni were able to switch at ultralow currents (RESET current <1 nA) by using a low compliance current (<500 nA). The low current is attributed to the tunneling barrier formed by the native SiO2 at the Ni silicide/HfO2 interface.

  16. Total ionizing dose effect of γ-ray radiation on the switching characteristics and filament stability of HfOx resistive random access memory

    SciTech Connect

    Fang, Runchen; Yu, Shimeng; Gonzalez Velo, Yago; Chen, Wenhao; Holbert, Keith E.; Kozicki, Michael N.; Barnaby, Hugh

    2014-05-05

    The total ionizing dose (TID) effect of gamma-ray (γ-ray) irradiation on HfOx based resistive random access memory was investigated by electrical and material characterizations. The memory states can sustain TID level ∼5.2 Mrad (HfO{sub 2}) without significant change in the functionality or the switching characteristics under pulse cycling. However, the stability of the filament is weakened after irradiation as memory states are more vulnerable to flipping under the electrical stress. X-ray photoelectron spectroscopy was performed to ascertain the physical mechanism of the stability degradation, which is attributed to the Hf-O bond breaking by the high-energy γ-ray exposure.

  17. Optoelectrical Molybdenum Disulfide (MoS2)--Ferroelectric Memories.

    PubMed

    Lipatov, Alexey; Sharma, Pankaj; Gruverman, Alexei; Sinitskii, Alexander

    2015-08-25

    In this study, we fabricated and tested electronic and memory properties of field-effect transistors (FETs) based on monolayer or few-layer molybdenum disulfide (MoS2) on a lead zirconium titanate (Pb(Zr,Ti)O3, PZT) substrate that was used as a gate dielectric. MoS2-PZT FETs exhibit a large hysteresis of electronic transport with high ON/OFF ratios. We demonstrate that the interplay of polarization and interfacial phenomena strongly affects the electronic behavior and memory characteristics of MoS2-PZT FETs. We further demonstrate that MoS2-PZT memories have a number of advantages and unique features compared to their graphene-based counterparts as well as commercial ferroelectric random-access memories (FeRAMs), such as nondestructive data readout, low operation voltage, wide memory window and the possibility to write and erase them both electrically and optically. This dual optoelectrical operation of these memories can simplify the device architecture and offer additional practical functionalities, such as an instant optical erase of large data arrays that is unavailable for many conventional memories. PMID:26222209

  18. Resistive Switching Behavior in Organic-Inorganic Hybrid CH3 NH3 PbI3-x Clx Perovskite for Resistive Random Access Memory Devices.

    PubMed

    Yoo, Eun Ji; Lyu, Miaoqiang; Yun, Jung-Ho; Kang, Chi Jung; Choi, Young Jin; Wang, Lianzhou

    2015-10-28

    The CH3 NH3 PbI3- x Clx organic-inorganic hybrid perovskite material demonstrates remarkable resistive switching behavior, which can be applicable in resistive random access memory devices. The simply designed Au/CH3 NH3 PbI3- x Clx /FTO structure is fabricated by a low-temperature, solution-processable method, which exhibits remarkable bipolar resistive switching and nonvolatile properties. PMID:26331363

  19. The future of memory

    NASA Astrophysics Data System (ADS)

    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 (< 100 ns read/write), excellent endurance (> 1012), nonvolatility (retention > 10 years), and low switching energies (< 10 pJ per switch). The International 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.

  20. USER'S GUIDE FOR RAM. SECOND EDITION

    EPA Science Inventory

    RAM is an air quality model based on the Gaussian-plume simplication of the diffusion equation which assumes time independence in the input meteorology and concentration. The model is primarily used to determine short-term (one hour to one day) concentrations from point and area ...

  1. 3. Light tower, view northwest, south side Ram Island ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Light tower, view northwest, south side - Ram Island Light Station, Ram Island, south of Ocean Point & just north of Fisherman Island, marking south side of Fisherman Island Passage, Ocean Point, Lincoln County, ME

  2. Improving high-resistance state uniformity and leakage current for polyimide-based resistive switching memory by rubbing post-treatment

    NASA Astrophysics Data System (ADS)

    Hsiao, Yu-Ping; Yang, Wen-Luh; Wu, Chi-Chang; Lin, Li-Min; Chin, Fun-Tat; Lin, Yu-Hsien; Yang, Ke-Luen

    2016-01-01

    In this study, a polyimide (PI) thin film is synthesized as a resistive switching layer for resistive random access memory (ReRAM) applications. The experimental results on polyimide thickness show that the Schottky effect between the interface of polyimide and metal thin films is the dominant mechanism in the high-resistance state (HRS). We, therefore, propose a rubbing post-treatment to improve the device performance. Results show that the uniformity and leakage of the memory in the HRS, as well as the power consumption in the low-resistance state (LRS), are improved. The power density of the set process is less than half after the rubbing post-treatment. Moreover, the power density of the reset process can be markedly decreased by about two orders of magnitude. In addition, the rubbed ReRAM exhibits a stable storage capability with seven orders of magnitude ION/IOFF current ratio at 85 °C.

  3. Memory protection

    NASA Technical Reports Server (NTRS)

    Denning, Peter J.

    1988-01-01

    Accidental overwriting of files or of memory regions belonging to other programs, browsing of personal files by superusers, Trojan horses, and viruses are examples of breakdowns in workstations and personal computers that would be significantly reduced by memory protection. Memory protection is the capability of an operating system and supporting hardware to delimit segments of memory, to control whether segments can be read from or written into, and to confine accesses of a program to its segments alone. The absence of memory protection in many operating systems today is the result of a bias toward a narrow definition of performance as maximum instruction-execution rate. A broader definition, including the time to get the job done, makes clear that cost of recovery from memory interference errors reduces expected performance. The mechanisms of memory protection are well understood, powerful, efficient, and elegant. They add to performance in the broad sense without reducing instruction execution rate.

  4. Implementation of nitrogen-doped titanium-tungsten tunable heater in phase change random access memory and its effects on device performance

    SciTech Connect

    Tan, Chun Chia; Zhao, Rong Chong, Tow Chong; Shi, Luping

    2014-10-13

    Nitrogen-doped titanium-tungsten (N-TiW) was proposed as a tunable heater in Phase Change Random Access Memory (PCRAM). By tuning N-TiW's material properties through doping, the heater can be tailored to optimize the access speed and programming current of PCRAM. Experiments reveal that N-TiW's resistivity increases and thermal conductivity decreases with increasing nitrogen-doping ratio, and N-TiW devices displayed (∼33% to ∼55%) reduced programming currents. However, there is a tradeoff between the current and speed for heater-based PCRAM. Analysis of devices with different N-TiW heaters shows that N-TiW doping levels could be optimized to enable low RESET currents and fast access speeds.

  5. A Monte Carlo simulation for bipolar resistive memory switching in large band-gap oxides

    SciTech Connect

    Hur, Ji-Hyun E-mail: jeonsh@korea.ac.kr; Lee, Dongsoo; Jeon, Sanghun E-mail: jeonsh@korea.ac.kr

    2015-11-16

    A model that describes bilayered bipolar resistive random access memory (BL-ReRAM) switching in oxide with a large band gap is presented. It is shown that, owing to the large energy barrier between the electrode and thin oxide layer, the electronic conduction is dominated by trap-assisted tunneling. The model is composed of an atomic oxygen vacancy migration model and an electronic tunneling conduction model. We also show experimentally observed three-resistance-level switching in Ru/ZrO{sub 2}/TaO{sub x} BL-ReRAM that can be explained by the two types of traps, i.e., shallow and deep traps in ZrO{sub 2}.

  6. Nanofilament Dynamics in Resistance Memory: Model and Validation.

    PubMed

    Lu, Yang; Lee, Jong Ho; Chen, I-Wei

    2015-07-28

    Filamentary resistive random-access memory (ReRAM) employs a single nanoscale event to trigger a macroscopic state change. While fundamentally it involves a gradual electrochemical evolution in a nanoscale filament that culminates in an abrupt change in filament's resistance, understanding over many length and time scales from the filament level to the device level is needed to inform the device behavior. Here, we demonstrate the nanoscale elements have corresponding elements in an empirical equivalent circuit. Specifically, the filament contains a variable resistor and capacitor that switch at a critical voltage. This simple model explains several observations widely reported on disparate filamentary ReRAMs. In particular, its collective system dynamics incorporating the power-law time-relaxation of the variable capacitance can accurately account for the responses of variously sized single-filament HfOx ReRAMs to DC/quasi-static and pulse electrical stimulation, exhibiting Avrami-like switching kinetics and a pulse-rate dependence in on/off voltages. PMID:26102522

  7. Detrimental effect of interfacial Dzyaloshinskii-Moriya interaction on perpendicular spin-transfer-torque magnetic random access memory

    SciTech Connect

    Jang, Peong-Hwa; Lee, Seo-Won E-mail: kj-lee@korea.ac.kr; Song, Kyungmi; Lee, Seung-Jae; Lee, Kyung-Jin E-mail: kj-lee@korea.ac.kr

    2015-11-16

    Interfacial Dzyaloshinskii-Moriya interaction in ferromagnet/heavy metal bilayers is recently of considerable interest as it offers an efficient control of domain walls and the stabilization of magnetic skyrmions. However, its effect on the performance of perpendicular spin transfer torque memory has not been explored yet. We show based on numerical studies that the interfacial Dzyaloshinskii-Moriya interaction decreases the thermal energy barrier while increases the switching current. As high thermal energy barrier as well as low switching current is required for the commercialization of spin torque memory, our results suggest that the interfacial Dzyaloshinskii-Moriya interaction should be minimized for spin torque memory applications.

  8. A simple device unit consisting of all NiO storage and switch elements for multilevel terabit nonvolatile random access memory.

    PubMed

    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. PMID:21988144

  9. Semen characteristics after vasectomy in the ram.

    PubMed

    Janett, F; Hüssy, D; Lischer, C; Hässig, M; Thun, R

    2001-08-01

    The objective of this study was to monitor the changes in semen characteristics in vasectomized rams and to determine if infertility was present 14 days after vasectomy. Experiments were performed using five cross-breed rams, aged between 18 and 30 months. Semen was collected weekly by artificial vagina from 2 months before to 5 months after vasectomy. After sexual rest for 10 days, vasectomy was performed by the cranial midscrotal approach. In all ejaculates the volume, concentration, total sperm number, motility and morphology (normal spermatozoa, loose heads) were determined and sperm viability (SYBR-14/PI) was evaluated in all semen samples collected after vasectomy. In the first ejaculate obtained 14 days post vasectomy all rams showed a significant (P < 0.05) drop in mean volume (from 1.2 to 0.5 mL), total sperm count (from 5176.8 to 51.1 x 10(6)) and morphologically normal sperm (from 84.1 to 15.7%), when compared to the last prevasectomy collection. We could also demonstrate a positive correlation (r = 0.89) between the individual cumulative total number of spermatozoa after vasectomy and the scrotal circumference measured before vasectomy. Sperm motility and viability could never be demonstrated after vasectomy and normal spermatozoa continuously decreased concomitant with an increase in loose heads. On post mortem examination 5 months after surgery, spermatocele formation and multiple sperm granulomas were present in all five rams. Our results show that in the first ejaculate collected by artificial vagina 14 days after vasectomy, no motile and viable spermatozoa could be detected. Despite weekly collections during a 5-month period after sterilization, azoospermia could never be achieved. PMID:11516127

  10. Simulation of the Effects of Radiation on a Satellite Memory and Improving Its Fault-Tolerant Ability, Using SIHFT

    NASA Astrophysics Data System (ADS)

    Nematollahzadeh, S. M.; Jamshidifar, A. A.

    This chapter describes a software environment based on VirSim tool to simulate the effect of radiation on COTS (commercial off-the-shelf) memories and shows the efficiency of the software EDAC (error detection and correction). As a case study, a sample student LEO (low Earth orbit) satellite with 8-MB (megabytes) RAM (random access memory) is considered and software EDAC for detecting and correcting the faults in the memory is implemented. The software EDAC is responsible for reliability of data in this 8-MB RAM. One separated task in VirSim tool has been developed for injection SEUs (single event upset) to the 8-MB memory of the satellite. The SEUs have been generated based on the ARGOS satellite reports. According to these reports the average of SEUs is about 5.5 SEU/MB per day, where it generates about 5 MBU (multiple bit upset) out of any 100 SEU. About four of these MBUs are double events (2-bit upset in one word) and one of them is triple. The software EDAC detects and corrects all 1-bit SEUs and detects double MBUs but it does not guarantee the detection of triple MBUs. This kind of simulation is very simple, accessible, and very close to the real environment and one can use it for checking effectiveness of the approach. The simulation results demonstrate efficacy of the approach in terms of fault detection and correction capabilities.

  11. Structural changes and conductance thresholds in metal-free intrinsic SiO{sub x} resistive random access memory

    SciTech Connect

    Mehonic, Adnan E-mail: t.kenyon@ucl.ac.uk; Buckwell, Mark; Montesi, Luca; Garnett, Leon; Hudziak, Stephen; Kenyon, Anthony J. E-mail: t.kenyon@ucl.ac.uk; Fearn, Sarah; Chater, Richard; McPhail, David

    2015-03-28

    We present an investigation of structural changes in silicon-rich silicon oxide metal-insulator-metal resistive RAM devices. The observed unipolar switching, which is intrinsic to the bulk oxide material and does not involve movement of metal ions, correlates with changes in the structure of the oxide. We use atomic force microscopy, conductive atomic force microscopy, x-ray photoelectron spectroscopy, and secondary ion mass spectroscopy to examine the structural changes occurring as a result of switching. We confirm that protrusions formed at the surface of samples during switching are bubbles, which are likely to be related to the outdiffusion of oxygen. This supports existing models for valence-change based resistive switching in oxides. In addition, we describe parallel linear and nonlinear conduction pathways and suggest that the conductance quantum, G{sub 0}, is a natural boundary between the high and low resistance states of our devices.

  12. Spacecraft ram glow and surface temperature

    NASA Technical Reports Server (NTRS)

    Swenson, G. R.; Mende, S. B.; Llewellyn, E. J.

    1987-01-01

    Space shuttle glow intensity measurements show large differences when the data from different missions are compared. In particular, on the 41-G mission the space shuttle ram glow was observed to display an unusually low intensity. Subsequent investigation of this measurement and earlier measurements suggest that there was a significant difference in temperature of the glow producing ram surfaces. The highly insulating properties coupled with the high emissivity of the shuttle tile results in surfaces that cool quickly when exposed to deep space on the night side of the orbit. The increased glow intensity is consistent with the hypothesis that the glow is emitted from excited NO2. The excited NO2 is likely formed through three body recombination (OI + NO + M = NO2*) where ramming of OI interacts with weakly surface bound NO. The NO is formed from atmospheric OI and NI which is scavenged by the spacecraft moving through the atmosphere. It is postulated that the colder surfaces retain a thicker layer of NO thereby increasing the probability of the reaction. It has been found from the glow intensity/temperature data that the bond energy of the surface bound precursor, leading to the chemical recombination producing the glow, is approximately 0.14 eV. A thermal analysis of material samples of STS-8 was made and the postulated temperature change of individual material samples prior to the time of glow measurements above respective samples are consistent with the thermal effect on glow found for the orbiter surface.

  13. Quantifying data retention of perpendicular spin-transfer-torque magnetic random access memory chips using an effective thermal stability factor method

    SciTech Connect

    Thomas, Luc Jan, Guenole; Le, Son; Wang, Po-Kang

    2015-04-20

    The thermal stability of perpendicular Spin-Transfer-Torque Magnetic Random Access Memory (STT-MRAM) devices is investigated at chip level. Experimental data are analyzed in the framework of the Néel-Brown model including distributions of the thermal stability factor Δ. We show that in the low error rate regime important for applications, the effect of distributions of Δ can be described by a single quantity, the effective thermal stability factor Δ{sub eff}, which encompasses both the median and the standard deviation of the distributions. Data retention of memory chips can be assessed accurately by measuring Δ{sub eff} as a function of device diameter and temperature. We apply this method to show that 54 nm devices based on our perpendicular STT-MRAM design meet our 10 year data retention target up to 120 °C.

  14. Investigation of thermal stability and reliability of HfO2 based resistive random access memory devices with cross-bar structure

    NASA Astrophysics Data System (ADS)

    Chand, Umesh; Huang, Kuan-Chang; Huang, Chun-Yang; Ho, Chia-Hua; Lin, Chen-Hsi; Tseng, Tseung-Yuen

    2015-05-01

    The effect of the annealing treatment of a HfO2 resistive switching layer and the memory performance of a HfO2-based resistive random access memory (cross-bar structure) device were investigated. Oxygen is released from HfO2 resistive switching layers during vacuum annealing, leading to unstable resistive switching properties. This oxygen release problem can be suppressed by inserting an Al2O3 thin film, which has a lower Gibbs free energy, between the HfO2 layer and top electrode to form a Ti/Al2O3/HfO2/TiN structure. This device structure exhibited good reliability after high temperature vacuum annealing and post metal annealing (PMA) treatments. Moreover, the endurance and retention properties of the device were also improved after the PMA treatment.

  15. Reducing operation voltages by introducing a low-k switching layer in indium–tin-oxide-based resistance random access memory

    NASA Astrophysics Data System (ADS)

    Jin, Fu-Yuan; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Pan, Chih-Hung; Lin, Chih-Yang; Chen, Po-Hsun; Chen, Min-Chen; Huang, Hui-Chun; Lo, Ikai; Zheng, Jin-Cheng; Sze, Simon M.

    2016-06-01

    In this letter, we inserted a low dielectric constant (low-k) or high dielectric constant (high-k) material as a switching layer in indium–tin-oxide-based resistive random-access memory. After measuring the two samples, we found that the low-k material device has very low operating voltages (‑80 and 110 mV for SET and RESET operations, respectively). Current fitting results were then used with the COMSOL software package to simulate electric field distribution in the layers. After combining the electrical measurement results with simulations, a conduction model was proposed to explain resistance switching behaviors in the two structures.

  16. Bit Distribution and Reliability of High Density 1.5 V Ferroelectric Random Access Memory Embedded with 130 nm, 5 lm Copper Complementary Metal Oxide Semiconductor Logic

    NASA Astrophysics Data System (ADS)

    Udayakumar, K. R.; Boku, K.; Remack, K. A.; Rodriguez, J.; Summerfelt, S. R.; Celii, F. G.; Aggarwal, S.; Martin, J. S.; Hall, L.; Matz, L.; Rathsack, B.; McAdams, H.; Moise, T. S.

    2006-04-01

    High density embedded ferroelectric random access memory (FRAM), operable at 1.5 V, has been fabricated within a 130 nm, 5 lm Cu/fluorosilicate glass (FSG) logic process. To evaluate FRAM extendability to future process nodes, we have measured the bit distribution and reliability properties of arrays with varying individual capacitor areas ranging from 0.40 μm2 (130 nm node) to 0.15 μm2 (˜65 nm node). Wide signal margins, stable retention (≫10 years at 85 °C), and high endurance read/write cycling (≫1012 cycles) have been demonstrated, suggesting that reliable, high density FRAM can be realized.

  17. Mechanism of power consumption inhibitive multi-layer Zn:SiO2/SiO2 structure resistance random access memory

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Tsai, Tsung-Ming; Chang, Ting-Chang; Chang, Kuan-Chang; Chen, Kai-Huang; Lou, Jen-Chung; Young, Tai-Fa; Chen, Jung-Hui; Huang, Syuan-Yong; Chen, Min-Chen; Shih, Chih-Cheng; Chen, Hsin-Lu; Pan, Jhih-Hong; Tung, Cheng-Wei; Syu, Yong-En; Sze, Simon M.

    2013-12-01

    In this paper, multi-layer Zn:SiO2/SiO2 structure is introduced to reduce the operation power consumption of resistive random access memory (RRAM) device by modifying the filament formation process. And the configuration of multi-layer Zn:SiO2/SiO2 structure is confirmed and demonstrated by auger electron spectrum. Material analysis together with conduction current fitting is applied to qualitatively evaluate the carrier conduction mechanism on both low resistance state and high resistance state. Finally, single layer and multilayer conduction models are proposed, respectively, to clarify the corresponding conduction characteristics of two types of RRAM devices.

  18. Mechanism of power consumption inhibitive multi-layer Zn:SiO{sub 2}/SiO{sub 2} structure resistance random access memory

    SciTech Connect

    Zhang, Rui; Lou, Jen-Chung; Tsai, Tsung-Ming E-mail: tcchang@mail.phys.nsysu.edu.tw; Chang, Kuan-Chang; Huang, Syuan-Yong; Shih, Chih-Cheng; Pan, Jhih-Hong; Tung, Cheng-Wei; Chang, Ting-Chang E-mail: tcchang@mail.phys.nsysu.edu.tw; Chen, Kai-Huang; Young, Tai-Fa; Chen, Hsin-Lu; Chen, Jung-Hui; Chen, Min-Chen; Syu, Yong-En; Sze, Simon M.

    2013-12-21

    In this paper, multi-layer Zn:SiO{sub 2}/SiO{sub 2} structure is introduced to reduce the operation power consumption of resistive random access memory (RRAM) device by modifying the filament formation process. And the configuration of multi-layer Zn:SiO{sub 2}/SiO{sub 2} structure is confirmed and demonstrated by auger electron spectrum. Material analysis together with conduction current fitting is applied to qualitatively evaluate the carrier conduction mechanism on both low resistance state and high resistance state. Finally, single layer and multilayer conduction models are proposed, respectively, to clarify the corresponding conduction characteristics of two types of RRAM devices.

  19. 39% access time improvement, 11% energy reduction, 32 kbit 1-read/1-write 2-port static random-access memory using two-stage read boost and write-boost after read sensing scheme

    NASA Astrophysics Data System (ADS)

    Yamamoto, Yasue; Moriwaki, Shinichi; Kawasumi, Atsushi; Miyano, Shinji; Shinohara, Hirofumi

    2016-04-01

    We propose novel circuit techniques for 1 clock (1CLK) 1 read/1 write (1R/1W) 2-port static random-access memories (SRAMs) to improve read access time (tAC) and write margins at low voltages. Two-stage read boost (TSR-BST) and write word line boost (WWL-BST) after the read sensing schemes have been proposed. TSR-BST reduces the worst read bit line (RBL) delay by 61% and RBL amplitude by 10% at V DD = 0.5 V, which improves tAC by 39% and reduces energy dissipation by 11% at V DD = 0.55 V. WWL-BST after read sensing scheme improves minimum operating voltage (V min) by 140 mV. A 32 kbit 1CLK 1R/1W 2-port SRAM with TSR-BST and WWL-BST has been developed using a 40 nm CMOS.

  20. MSIX - A general and user-friendly platform for RAM analysis

    NASA Astrophysics Data System (ADS)

    Pan, Z. J.; Blemel, Peter

    The authors present a CAD (computer-aided design) platform supporting RAM (reliability, availability, and maintainability) analysis with efficient system description and alternative evaluation. The design concepts, implementation techniques, and application results are described. This platform is user-friendly because of its graphic environment, drawing facilities, object orientation, self-tutoring, and access to the operating system. The programs' independency and portability make them generally applicable to various analysis tasks.

  1. Incorporation of RAM techniques into simulation modeling

    NASA Astrophysics Data System (ADS)

    Nelson, S. C., Jr.; Haire, M. J.; Schryver, J. C.

    1995-01-01

    This work concludes that reliability, availability, and maintainability (RAM) analytical techniques can be incorporated into computer network simulation modeling to yield an important new analytical tool. This paper describes the incorporation of failure and repair information into network simulation to build a stochastic computer model to represent the RAM Performance of two vehicles being developed for the US Army: The Advanced Field Artillery System (AFAS) and the Future Armored Resupply Vehicle (FARV). The AFAS is the US Army's next generation self-propelled cannon artillery system. The FARV is a resupply vehicle for the AFAS. Both vehicles utilize automation technologies to improve the operational performance of the vehicles and reduce manpower. The network simulation model used in this work is task based. The model programmed in this application requirements a typical battle mission and the failures and repairs that occur during that battle. Each task that the FARV performs--upload, travel to the AFAS, refuel, perform tactical/survivability moves, return to logistic resupply, etc.--is modeled. Such a model reproduces a model reproduces operational phenomena (e.g., failures and repairs) that are likely to occur in actual performance. Simulation tasks are modeled as discrete chronological steps; after the completion of each task decisions are programmed that determine the next path to be followed. The result is a complex logic diagram or network. The network simulation model is developed within a hierarchy of vehicle systems, subsystems, and equipment and includes failure management subnetworks. RAM information and other performance measures are collected which have impact on design requirements. Design changes are evaluated through 'what if' questions, sensitivity studies, and battle scenario changes.

  2. SiO2 doped Ge2Sb2Te5 thin films with high thermal efficiency for applications in phase change random access memory.

    PubMed

    Ryu, Seung Wook; Lyeo, Ho-Ki; Lee, Jong Ho; Ahn, Young Bae; Kim, Gun Hwan; Kim, Choon Hwan; Kim, Soo Gil; Lee, Se-Ho; Kim, Ka Young; Kim, Jong Hyeop; Kim, Won; Hwang, Cheol Seong; Kim, Hyeong Joon

    2011-06-24

    This study examined the various physical, structural and electrical properties of SiO(2) doped Ge(2)Sb(2)Te(5) (SGST) films for phase change random access memory applications. Interestingly, SGST had a layered structure (LS) resulting from the inhomogeneous distribution of SiO(2) after annealing. The physical parameters able to affect the reset current of phase change memory (I(res)) were predicted from the Joule heating and heat conservation equations. When SiO(2) was doped into GST, thermal conductivity largely decreased by ∼ 55%. The influence of SiO(2)-doping on I(res) was examined using the test phase change memory cell. I(res) was reduced by ∼ 45%. An electro-thermal simulation showed that the reduced thermal conductivity contributes to the improvement of cell efficiency as well as the reduction of I(res), while the increased dynamic resistance contributes only to the latter. The formation and presence of the LS thermal conductivity in the set state test cell after repeated switching was confirmed. PMID:21572208

  3. a-SiNx:H-based ultra-low power resistive random access memory with tunable Si dangling bond conduction paths

    PubMed Central

    Jiang, Xiaofan; Ma, Zhongyuan; Xu, Jun; Chen, Kunji; Xu, Ling; Li, Wei; Huang, Xinfan; Feng, Duan

    2015-01-01

    The realization of ultra-low power Si-based resistive switching memory technology will be a milestone in the development of next generation non-volatile memory. Here we show that a high performance and ultra-low power resistive random access memory (RRAM) based on an Al/a-SiNx:H/p+-Si structure can be achieved by tuning the Si dangling bond conduction paths. We reveal the intrinsic relationship between the Si dangling bonds and the N/Si ratio x for the a-SiNx:H films, which ensures that the programming current can be reduced to less than 1 μA by increasing the value of x. Theoretically calculated current-voltage (I–V ) curves combined with the temperature dependence of the I–V characteristics confirm that, for the low-resistance state (LRS), the Si dangling bond conduction paths obey the trap-assisted tunneling model. In the high-resistance state (HRS), conduction is dominated by either hopping or Poole–Frenkel (P–F) processes. Our introduction of hydrogen in the a-SiNx:H layer provides a new way to control the Si dangling bond conduction paths, and thus opens up a research field for ultra-low power Si-based RRAM. PMID:26508086

  4. a-SiNx:H-based ultra-low power resistive random access memory with tunable Si dangling bond conduction paths.

    PubMed

    Jiang, Xiaofan; Ma, Zhongyuan; Xu, Jun; Chen, Kunji; Xu, Ling; Li, Wei; Huang, Xinfan; Feng, Duan

    2015-01-01

    The realization of ultra-low power Si-based resistive switching memory technology will be a milestone in the development of next generation non-volatile memory. Here we show that a high performance and ultra-low power resistive random access memory (RRAM) based on an Al/a-SiNx:H/p(+)-Si structure can be achieved by tuning the Si dangling bond conduction paths. We reveal the intrinsic relationship between the Si dangling bonds and the N/Si ratio x for the a-SiNx:H films, which ensures that the programming current can be reduced to less than 1 μA by increasing the value of x. Theoretically calculated current-voltage (I-V) curves combined with the temperature dependence of the I-V characteristics confirm that, for the low-resistance state (LRS), the Si dangling bond conduction paths obey the trap-assisted tunneling model. In the high-resistance state (HRS), conduction is dominated by either hopping or Poole-Frenkel (P-F) processes. Our introduction of hydrogen in the a-SiNx:H layer provides a new way to control the Si dangling bond conduction paths, and thus opens up a research field for ultra-low power Si-based RRAM. PMID:26508086

  5. a-SiNx:H-based ultra-low power resistive random access memory with tunable Si dangling bond conduction paths

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaofan; Ma, Zhongyuan; Xu, Jun; Chen, Kunji; Xu, Ling; Li, Wei; Huang, Xinfan; Feng, Duan

    2015-10-01

    The realization of ultra-low power Si-based resistive switching memory technology will be a milestone in the development of next generation non-volatile memory. Here we show that a high performance and ultra-low power resistive random access memory (RRAM) based on an Al/a-SiNx:H/p+-Si structure can be achieved by tuning the Si dangling bond conduction paths. We reveal the intrinsic relationship between the Si dangling bonds and the N/Si ratio x for the a-SiNx:H films, which ensures that the programming current can be reduced to less than 1 μA by increasing the value of x. Theoretically calculated current-voltage (I-V ) curves combined with the temperature dependence of the I-V characteristics confirm that, for the low-resistance state (LRS), the Si dangling bond conduction paths obey the trap-assisted tunneling model. In the high-resistance state (HRS), conduction is dominated by either hopping or Poole-Frenkel (P-F) processes. Our introduction of hydrogen in the a-SiNx:H layer provides a new way to control the Si dangling bond conduction paths, and thus opens up a research field for ultra-low power Si-based RRAM.

  6. Stability scheme of ZnO-thin film resistive switching memory: influence of defects by controllable oxygen pressure ratio

    PubMed Central

    2013-01-01

    We report a stability scheme of resistive switching devices based on ZnO films deposited by radio frequency (RF) sputtering process at different oxygen pressure ratios. I-V measurements and statistical results indicate that the operating stability of ZnO resistive random access memory (ReRAM) devices is highly dependent on oxygen conditions. Data indicates that the ZnO film ReRAM device fabricated at 10% O2 pressure ratio exhibits the best performance. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) of ZnO at different O2 pressure ratios were investigated to reflect influence of structure to the stable switching behaviors. In addition, PL and XPS results were measured to investigate the different charge states triggered in ZnO by oxygen vacancies, which affect the stability of the switching behavior. PMID:24237683

  7. Accessing Epstein-Barr Virus-Specific T-Cell Memory with Peptide-Loaded Dendritic Cells

    PubMed Central

    Redchenko, I. V.; Rickinson, A. B.

    1999-01-01

    The conventional means of studying Epstein-Barr virus (EBV)-induced cytotoxic T-lymphocyte (CTL) memory, by in vitro stimulation with the latently infected autologous lymphoblastoid cell line (LCL), has important limitations. First, it gives no information on memory to lytic cycle antigens; second, it preferentially amplifies the dominant components of latent antigen-specific memory at the expense of key subdominant reactivities. Here we describe an alternative approach, based on in vitro stimulation with epitope peptide-loaded dendritic cells (DCs), which allows one to probe the CTL repertoire for any individual reactivity of choice; this method proved significantly more efficient than stimulation with peptide alone. Using this approach we first show that reactivities to the immunodominant and subdominant lytic cycle epitopes identified by T cells during primary EBV infection are regularly detectable in the CTL memory of virus carriers; this implies that in such carriers chronic virus replication remains under direct T-cell control. We further show that subdominant latent cycle reactivities to epitopes in the latent membrane protein LMP2, though rarely undetectable in LCL-stimulated populations, can be reactivated by DC stimulation and selectively expanded as polyclonal CTL lines; the adoptive transfer of such preparations may be of value in targeting certain EBV-positive malignancies. PMID:9847337

  8. Loss of Object Recognition Memory Produced by Extended Access to Methamphetamine Self-Administration is Reversed by Positive Allosteric Modulation of Metabotropic Glutamate Receptor 5

    PubMed Central

    Reichel, Carmela M; Schwendt, Marek; McGinty, Jacqueline F; Olive, M Foster; See, Ronald E

    2011-01-01

    Chronic methamphetamine (meth) abuse can lead to persisting cognitive deficits. Here, we utilized a long-access meth self-administration (SA) protocol to assess recognition memory and metabotropic glutamate receptor (mGluR) expression, and the possible reversal of cognitive impairments with the mGluR5 allosteric modulator, 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl) benzamide (CDPPB). Male, Long-Evans rats self-administered i.v. meth (0.02 mg/infusion) on an FR1 schedule of reinforcement or received yoked-saline infusions. After seven daily 1-h sessions, rats were switched to 6-h daily sessions for 14 days, and then underwent drug abstinence. Rats were tested for object recognition memory at 1 week after meth SA at 90 min and 24 h retention intervals. In a separate experiment, rats underwent the same protocol, but received either vehicle or CDPPB (30 mg/kg) after familiarization. Rats were killed on day 8 or 14 post-SA and brain tissue was obtained. Meth intake escalated over the extended access period. Additionally, meth-experienced rats showed deficits in both short- and long-term recognition memory, demonstrated by a lack of novel object exploration. The deficit at 90 min was reversed by CDPPB treatment. On day 8, meth intake during SA negatively correlated with mGluR expression in the perirhinal and prefrontal cortex, and mGluR5 receptor expression was decreased 14 days after discontinuation of meth. This effect was specific to mGluR5 levels in the perirhinal cortex, as no differences were identified in the hippocampus or in mGluR2/3 receptors. These results from a clinically-relevant animal model of addiction suggest that mGluR5 receptor modulation may be a potential treatment of cognitive dysfunction in meth addiction. PMID:21150906

  9. Complementary resistive switches for passive nanocrossbar memories.

    PubMed

    Linn, Eike; Rosezin, Roland; Kügeler, Carsten; Waser, Rainer

    2010-05-01

    On the road towards higher memory density and computer performance, a significant improvement in energy efficiency constitutes the dominant goal in future information technology. Passive crossbar arrays of memristive elements were suggested a decade ago as non-volatile random access memories (RAM) and can also be used for reconfigurable logic circuits. As such they represent an interesting alternative to the conventional von Neumann based computer chip architectures. Crossbar architectures hold the promise of a significant reduction in energy consumption because of their ultimate scaling potential and because they allow for a local fusion of logic and memory, thus avoiding energy consumption by data transfer on the chip. However, the expected paradigm change has not yet taken place because the general problem of selecting a designated cell within a passive crossbar array without interference from sneak-path currents through neighbouring cells has not yet been solved satisfactorily. Here we introduce a complementary resistive switch. It consists of two antiserial memristive elements and allows for the construction of large passive crossbar arrays by solving the sneak path problem in combination with a drastic reduction of the power consumption. PMID:20400954

  10. SeaRAM: an evaluation of the safety of RAM transport by sea

    SciTech Connect

    McConnell, P.; Sorenson, K.B.; Carter, M.H.; Keane, M.P.; Keith, V.F.; Heid, R.J.

    1995-12-31

    SeaRAM is a multi-year Department of Energy (DOE) project designed to validate the safety of shipping radioactive materials (RAM) by sea. The project has an ultimate goal of developing and demonstrating analytic tools for performing comprehensive analyses to evaluate the risks to humans and the environment due to sea transport of plutonium, vitrified high-level waste (VHLW), and spent fuel associated with reprocessing and research reactors. To achieve this end, evaluations of maritime databases and structural an thermal analyses of particular severe collision and fire accidents have been and will continue to be conducted. Program management for SeaRAM is based at the DOE`s Office of Environmental Restoration. Technical activities for the project are being conducted at Sandia National Laboratories (SNL). Several private organizations are also involved in providing technical support, notably Engineering Computer Optecnomics, Inc. (ECO). The technical work performed for SeaRAM also supports DOE participation in an International Atomic Energy Agency (IAEA) Cooperative Research Program (CRP) entitled Accident Severity at Sea During Transport of Radioactive Material. This paper discusses activities performed during the first year of the project.

  11. A 1K Shadow RAM for circumvention applications

    SciTech Connect

    Murray, J.R.

    1991-01-01

    A 1K bit Shadow RAM has been developed for storage of critical data in a high transient radiation environment. The circuit includes a 1K bit (128 {times} 8) static RAM with two non-volatile (NV) shadows. The NV shadows are used to back-up the data in the static RAM allowing the circuit to be powered down during transient radiation without losing critical data. This paper will describe the circuit's operation and characterization results.

  12. The rams horn in western history

    NASA Astrophysics Data System (ADS)

    Lubman, David

    2003-10-01

    The shofar or rams horn-one of the most ancient of surviving aerophones-may have originated with early Neolithic herders. The shofar is mentioned frequently and importantly in the Hebrew bible and in later biblical and post-biblical literature. Despite its long history, contemporary ritual uses, and profound symbolic significance to western religion, no documentation of shofar acoustical properties was found. Since ancient times, shepherds of many cultures have fashioned sound instruments from the horns of herd animals for practical and musical uses. Shepherd horns of other cultures exhibit an evolution of form and technology (e.g., the inclusion of finger holes). The shofar is unique in having retained its primitive form. It is suggested that after centuries of practical use, the shofar became emblematic of the shepherd culture. Ritual use then developed, which froze its form. A modern ritual rams horn played by an experienced blower was examined. This rather short horn was determined to have a source strength of 92 dB (A) at 1 m, a fundamental frequency near 420 Hz, and maximum power output between 1.2 and 1.8 kHz. Sample sounds and detection range estimates are provided.

  13. A-SITE-AND/OR B-SITE-MODIFIED PBZRTIO3 MATERIALS AND (PB, SR, CA, BA, MG) (ZR, TI,NB, TA)O3 FILMS HAVING UTILITY IN FERROELECTRIC RANDOM ACCESS MEMORIES AND HIGH PERFORMANCE THIN FILM MICROACTUATORS

    NASA Technical Reports Server (NTRS)

    Roeder, Jeffrey F. (Inventor); Chen, Ing-Shin (Inventor); Bilodeau, Steven (Inventor); Baum, Thomas H. (Inventor)

    2004-01-01

    A modified PbZrTiO.sub.3 perovskite crystal material thin film, wherein the PbZrTiO.sub.3 perovskite crystal material includes crystal lattice A-sites and B-sites at least one of which is modified by the presence of a substituent selected from the group consisting of (i) A-site substituents consisting of Sr, Ca, Ba and Mg, and (ii) B-site substituents selected from the group consisting of Nb and Ta. The perovskite crystal thin film material may be formed by liquid delivery MOCVD from metalorganic precursors of the metal components of the thin film, to form PZT and PSZT, and other piezoelectric and ferroelectric thin film materials. The thin films of the invention have utility in non-volatile ferroelectric memory devices (NV-FeRAMs), and in microelectromechanical systems (MEMS) as sensor and/or actuator elements, e.g., high speed digital system actuators requiring low input power levels.

  14. TOPICAL REVIEW Nanoscale memory devices

    NASA Astrophysics Data System (ADS)

    Chung, Andy; Deen, Jamal; Lee, Jeong-Soo; Meyyappan, M.

    2010-10-01

    This article reviews the current status and future prospects for the use of nanomaterials and devices in memory technology. First, the status and continuing scaling trends of the flash memory are discussed. Then, a detailed discussion on technologies trying to replace flash in the near-term is provided. This includes phase change random access memory, Fe random access memory and magnetic random access memory. The long-term nanotechnology prospects for memory devices include carbon-nanotube-based memory, molecular electronics and memristors based on resistive materials such as TiO2.

  15. Reliable control of filament formation in resistive memories by self-assembled nanoinsulators derived from a block copolymer.

    PubMed

    You, Byoung Kuk; Park, Woon Ik; Kim, Jong Min; Park, Kwi-Il; Seo, Hyeon Kook; Lee, Jeong Yong; Jung, Yeon Sik; Lee, Keon Jae

    2014-09-23

    Resistive random access memory (ReRAM) is a promising candidate for future nonvolatile memories. Resistive switching in a metal-insulator-metal structure is generally assumed to be caused by the formation/rupture of nanoscale conductive filaments (CFs) under an applied electric field. The critical issue of ReRAM for practical memory applications, however, is insufficient repeatability of the operating voltage and resistance ratio. Here, we present an innovative approach to reliably and reproducibly control the CF growth in unipolar NiO resistive memory by exploiting uniform formation of insulating SiOx nanostructures from the self-assembly of a Si-containing block copolymer. In this way, the standard deviation (SD) of set and reset voltages was markedly reduced by 76.9% and 59.4%, respectively. The SD of high resistance state also decreased significantly, from 6.3 × 10(7) Ω to 5.4 × 10(4) Ω. Moreover, we report direct observations of localized metallic Ni CF formation and their controllable growth using electron microscopy and discuss electrothermal simulation results based on the finite element method supporting our analysis results. PMID:25192434

  16. Towards Terabit Memories

    NASA Astrophysics Data System (ADS)

    Hoefflinger, Bernd

    Memories have been the major yardstick for the continuing validity of Moore's law. In single-transistor-per-Bit dynamic random-access memories (DRAM), the number of bits per chip pretty much gives us the number of transistors. For decades, DRAM's have offered the largest storage capacity per chip. However, DRAM does not scale any longer, both in density and voltage, severely limiting its power efficiency to 10 fJ/b. A differential DRAM would gain four-times in density and eight-times in energy. Static CMOS RAM (SRAM) with its six transistors/cell is gaining in reputation because it scales well in cell size and operating voltage so that its fundamental advantage of speed, non-destructive read-out and low-power standby could lead to just 2.5 electrons/bit in standby and to a dynamic power efficiency of 2aJ/b. With a projected 2020 density of 16 Gb/cm², the SRAM would be as dense as normal DRAM and vastly better in power efficiency, which would mean a major change in the architecture and market scenario for DRAM versus SRAM. Non-volatile Flash memory have seen two quantum jumps in density well beyond the roadmap: Multi-Bit storage per transistor and high-density TSV (through-silicon via) technology. The number of electrons required per Bit on the storage gate has been reduced since their first realization in 1996 by more than an order of magnitude to 400 electrons/Bit in 2010 for a complexity of 32Gbit per chip at the 32 nm node. Chip stacking of eight chips with TSV has produced a 32GByte solid-state drive (SSD). A stack of 32 chips with 2 b/cell at the 16 nm node will reach a density of 2.5 Terabit/cm². Non-volatile memory with a density of 10 × 10 nm²/Bit is the target for widespread development. Phase-change memory (PCM) and resistive memory (RRAM) lead in cell density, and they will reach 20 Gb/cm² in 2D and higher with 3D chip stacking. This is still almost an order-of-magnitude less than Flash. However, their read-out speed is ~10-times faster, with as yet

  17. Single port-assisted fully laparoscopic abdominoperineal resection (APR) with immediate V-RAM flap reconstruction of the perineal defect.

    PubMed

    Ali, Sayid; Moftah, Mohamed; Ajmal, Nadeem; Cahill, Ronan A

    2012-09-01

    Abdominoperineal resection (APR) of anorectal cancers after neoadjuvant chemoradiotherapy may incur significant perineal morbidity. While vertical rectus abdominis muscle (V-RAM) flaps can fill the pelvic resection space with health tissue, their use has previously been described predominantly in association with laparotomy. Here, we describe a means of combination laparoscopic APR with V-RAM flap reconstruction that allows structural preservation of the entire abdominal wall throughout the oncological resection and of the deep parietal layers after V-RAM donation. Furthermore, a single port access device used at the end colostomy site allows a second senior surgeon assist with an additional two working instruments for the purpose of improved pelvic tissue retraction, especially useful in obese patients. PMID:22644717

  18. Space station synergetic RAM-logistics analysis

    NASA Technical Reports Server (NTRS)

    Dejulio, Edmund T.; Leet, Joel H.

    1988-01-01

    NASA's Space Station Maintenance Planning and Analysis (MP&A) Study is a step in the overall Space Station Program to define optimum approaches for on-orbit maintenance planning and logistics support. The approach used in the MP&A study and the analysis process used are presented. Emphasis is on maintenance activities and processes that can be accomplished on orbit within the known design and support constraints of the Space Station. From these analyses, recommendations for maintainability/maintenance requirements are established. The ultimate goal of the study is to reduce on-orbit maintenance requirements to a practical and safe minimum, thereby conserving crew time for productive endeavors. The reliability, availability, and maintainability (RAM) and operations performance evaluation models used were assembled and developed as part of the MP&A study and are described. A representative space station system design is presented to illustrate the analysis process.

  19. Feasibility of Integrated Insulation in Rammed Earth

    NASA Astrophysics Data System (ADS)

    Stone, C.; Balintova, M.; Holub, M.

    2015-11-01

    Building Codes in Europe stipulate strict thermal performance criteria which any traditional rammed earth recipe cannot meet. This does not infer that the material itself is inferior; it has many other face saving attributes such as low embodied energy, high workability, sound insulation, fire resistance, aesthetics, high diffusivity and thermal accumulation properties. Integrated insulation is experimented with, to try achieve a 0.22 [W/(m2.K)] overall coefficient of heat transfer for walls required by 2015 Slovak standards, without using external insulation or using technologically complex interstitial insulation. This has the added aesthetic benefit of leaving the earth wall exposed to the external environment. Results evaluate the feasibility of this traditional approach.

  20. Ease of Access to List Items in Short-Term Memory Depends on the Order of the Recognition Probes

    ERIC Educational Resources Information Center

    Lange, Elke B.; Cerella, John; Verhaeghen, Paul

    2011-01-01

    We report data from 4 experiments using a recognition design with multiple probes to be matched to specific study positions. Items could be accessed rapidly, independent of set size, when the test order matched the study order (forward condition). When the order of testing was random, backward, or in a prelearned irregular sequence (reordered…

  1. ViSA: A Neurodynamic Model for Visuo-Spatial Working Memory, Attentional Blink, and Conscious Access

    ERIC Educational Resources Information Center

    Simione, Luca; Raffone, Antonino; Wolters, Gezinus; Salmas, Paola; Nakatani, Chie; Belardinelli, Marta Olivetti; van Leeuwen, Cees

    2012-01-01

    Two separate lines of study have clarified the role of selectivity in conscious access to visual information. Both involve presenting multiple targets and distracters: one "simultaneously" in a spatially distributed fashion, the other "sequentially" at a single location. To understand their findings in a unified framework, we propose a…

  2. Detailed analysis of minimum operation voltage of extraordinarily unstable cells in fully depleted silicon-on-buried-oxide six-transistor static random access memory

    NASA Astrophysics Data System (ADS)

    Mizutani, Tomoko; Yamamoto, Yoshiki; Makiyama, Hideki; Yamashita, Tomohiro; Oda, Hidekazu; Kamohara, Shiro; Sugii, Nobuyuki; Hiramoto, Toshiro

    2015-04-01

    The minimum operation voltage (Vmin) of very unstable cells in silicon-on-thin-buried-oxide (SOTB) six-transistor (6T) static random access memory (SRAM) is analyzed in detail. It is found that the worst cell in 16k SRAM is very unstable and the stability characteristics of the worst cell correspond to approximately 6σ from those of the median cell. It is also found that extraordinarily unstable cells are much more sensitive to VTH change than median cells and that the static noise margin (SNM) and Vmin well correlate only in extraordinarily unstable cells. A simple VTH model for evaluating Vmin is developed and validated by Vmin measured in extraordinarily unstable cells.

  3. Closed-form analytical model of static noise margin for ultra-low voltage eight-transistor tunnel FET static random access memory

    NASA Astrophysics Data System (ADS)

    Fuketa, Hiroshi; O'uchi, Shin-ichi; Fukuda, Koichi; Mori, Takahiro; Morita, Yukinori; Masahara, Meishoku; Matsukawa, Takashi

    2016-04-01

    Variations of eight-transistor (8T) tunnel FET (TFET) static random access memory (SRAM) cells at ultra-low supply voltage (V DD) of 0.3 V are discussed. A closed-form analytical model for the static noise margin (SNM) of the TFET SRAM cells is proposed to clarify the dependence of SNM on device parameters and is verified by simulations. The SNM variations caused by process variations are investigated using the proposed model, and we show a requirement for the threshold voltage (V TH) variation in the TFET SRAM design, which indicates that the V TH variation must be reduced as the subthreshold swing becomes steeper. In addition, a feasibility of the TFET SRAM cells operating at V DD = 0.3 V in two different process technologies is evaluated using the proposed model.

  4. Self-compliance Pt/HfO2/Ti/Si one-diode-one-resistor resistive random access memory device and its low temperature characteristics

    NASA Astrophysics Data System (ADS)

    Lu, Chao; Yu, Jue; Chi, Xiao-Wei; Lin, Guang-Yang; Lan, Xiao-Ling; Huang, Wei; Wang, Jian-Yuan; Xu, Jian-Fang; Wang, Chen; Li, Cheng; Chen, Song-Yan; Liu, Chunli; Lai, Hong-Kai

    2016-04-01

    A bipolar one-diode-one-resistor (1D1R) device with a Pt/HfO2/Ti/n-Si(001) structure was demonstrated. The 1D1R resistive random access memory (RRAM) device consists of a Ti/n-Si(001) diode and a Pt/HfO2/Ti resistive switching cell. By using the Ti layer as the shared electrode for both the diode and the resistive switching cell, the 1D1R device exhibits the property of stable self-compliance and the characteristic of robust resistive switching with high uniformity. The high/low resistance ratio reaches 103. The electrical RESET/SET curve does not deteriorate after 68 loops. Low-temperature studies show that the 1D1R RRAM device has a critical working temperature of 250 K, and at temperatures below 250 K, the device fails to switch its resistances.

  5. Low leakage Ru-strontium titanate-Ru metal-insulator-metal capacitors for sub-20 nm technology node in dynamic random access memory

    NASA Astrophysics Data System (ADS)

    Popovici, M.; Swerts, J.; Redolfi, A.; Kaczer, B.; Aoulaiche, M.; Radu, I.; Clima, S.; Everaert, J.-L.; Van Elshocht, S.; Jurczak, M.

    2014-02-01

    Improved metal-insulator-metal capacitor (MIMCAP) stacks with strontium titanate (STO) as dielectric sandwiched between Ru as top and bottom electrode are shown. The Ru/STO/Ru stack demonstrates clearly its potential to reach sub-20 nm technology nodes for dynamic random access memory. Downscaling of the equivalent oxide thickness, leakage current density (Jg) of the MIMCAPs, and physical thickness of the STO have been realized by control of the Sr/Ti ratio and grain size using a heterogeneous TiO2/STO based nanolaminate stack deposition and a two-step crystallization anneal. Replacement of TiN with Ru as both top and bottom electrodes reduces the amount of electrically active defects and is essential to achieve a low leakage current in the MIM capacitor.

  6. Evaluation and Control of Break-Even Time of Nonvolatile Static Random Access Memory Based on Spin-Transistor Architecture with Spin-Transfer-Torque Magnetic Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Shuto, Yusuke; Yamamoto, Shuu'ichirou; Sugahara, Satoshi

    2012-04-01

    The energy performance of a nonvolatile static random access memory (NV-SRAM) cell for power gating applications was quantitatively analyzed for the first time using the performance index of break-even time (BET). The NV-SRAM cell is based on spin-transistor architecture using ordinary metal-oxide-semiconductor field-effect transistors (MOSFETs) and spin-transfer-torque magnetic tunnel junctions (STT-MTJs), whose circuit representation of spin-transistor is referred to as a pseudo-spin-MOSFET (PS-MOSFET). The cell is configured with a standard six-transistor SRAM cell and two PS-MOSFETs. The NV-SRAM cell basically has a short BET of submicroseconds. Although the write (store) operation to the STT-MTJs causes an increase in the BET, it can be successfully reduced by the proposed power-aware bias-control for the PS-MOSFETs.

  7. Low leakage Ru-strontium titanate-Ru metal-insulator-metal capacitors for sub-20 nm technology node in dynamic random access memory

    SciTech Connect

    Popovici, M. Swerts, J.; Redolfi, A.; Kaczer, B.; Aoulaiche, M.; Radu, I.; Clima, S.; Everaert, J.-L.; Van Elshocht, S.; Jurczak, M.

    2014-02-24

    Improved metal-insulator-metal capacitor (MIMCAP) stacks with strontium titanate (STO) as dielectric sandwiched between Ru as top and bottom electrode are shown. The Ru/STO/Ru stack demonstrates clearly its potential to reach sub-20 nm technology nodes for dynamic random access memory. Downscaling of the equivalent oxide thickness, leakage current density (J{sub g}) of the MIMCAPs, and physical thickness of the STO have been realized by control of the Sr/Ti ratio and grain size using a heterogeneous TiO{sub 2}/STO based nanolaminate stack deposition and a two-step crystallization anneal. Replacement of TiN with Ru as both top and bottom electrodes reduces the amount of electrically active defects and is essential to achieve a low leakage current in the MIM capacitor.

  8. Evaluation of in-plane local stress distribution in stacked IC chip using dynamic random access memory cell array for highly reliable three-dimensional IC

    NASA Astrophysics Data System (ADS)

    Tanikawa, Seiya; Kino, Hisashi; Fukushima, Takafumi; Koyanagi, Mitsumasa; Tanaka, Tetsu

    2016-04-01

    As three-dimensional (3D) ICs have many advantages, IC performances can be enhanced without scaling down of transistor size. However, 3D IC has mechanical stresses inside Si substrates owing to its 3D stacking structure, which induces negative effects on transistor performances such as carrier mobility changes. One of the mechanical stresses is local bending stress due to organic adhesive shrinkage among stacked IC chips. In this paper, we have proposed an evaluation method for in-plane local stress distribution in the stacked IC chips using retention time modulation of a dynamic random access memory (DRAM) cell array. We fabricated a test structure composed of a DRAM chip bonded on a Si interposer with dummy Cu/Sn microbumps. As a result, we clarified that the DRAM cell array can precisely evaluate the in-plane local stress distribution in the stacked IC chips.

  9. The reason for the increased threshold switching voltage of SiO2 doped Ge2Sb2Te5 thin films for phase change random access memory

    NASA Astrophysics Data System (ADS)

    Ryu, Seung Wook; Lee, Jong Ho; Ahn, Young Bae; Kim, Choon Hwan; Yang, Bong Seob; Kim, Gun Hwan; Kim, Soo Gil; Lee, Se-Ho; Hwang, Cheol Seong; Kim, Hyeong Joon

    2009-09-01

    This study examined the threshold switching voltage (VT) of 150 nm thick SiO2 doped Ge2Sb2Te5 (SGST) films for phase change random access memory applications. The VT of the SGST films increased from ˜0.9 V (for GST) to ˜1.5 V with increasing SiO2 content. The optical band gap and Urbach edge of the SGST films were similar regardless of the SiO2 concentration. The dielectric constant decreased by ˜37% and the electrical resistivity increased by ˜19%. The increase in VT of SGST films is associated with an effective increase in electric field and the decreased generation rate caused by impact ionization.

  10. Phase transformation behaviors of SiO2 doped Ge2Sb2Te5 films for application in phase change random access memory

    NASA Astrophysics Data System (ADS)

    Ryu, Seung Wook; Oh, Jin Ho; Lee, Jong Ho; Choi, Byung Joon; Kim, Won; Hong, Suk Kyoung; Hwang, Cheol Seong; Kim, Hyeong Joon

    2008-04-01

    The improvement in the phase change characteristics of Ge2Sb2Te5 (GST) films for phase change random access memory applications was investigated by doping the GST films with SiO2 using cosputtering at room temperature. As the sputtering power of SiO2 increased from 0to150W, the activation energy for crystallization increased from 2.1±0.2to3.1±0.15eV. SiO2 inhibited the crystallization of the amorphous GST films, which improved the long term stability of the metastable amorphous phase. The melting point decreased with increasing concentration of SiO2, which reduced the power consumption as well as the reset current.

  11. Multi-step resistive switching behavior of Li-doped ZnO resistance random access memory device controlled by compliance current

    NASA Astrophysics Data System (ADS)

    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.

  12. Correlative transmission electron microscopy and electrical properties study of switchable phase-change random access memory line cells

    SciTech Connect

    Oosthoek, J. L. M.; Kooi, B. J.; Voogt, F. C.; Attenborough, K.; Verheijen, M. A.; Hurkx, G. A. M.; Gravesteijn, D. J.

    2015-02-14

    Phase-change memory line cells, where the active material has a thickness of 15 nm, were prepared for transmission electron microscopy (TEM) observation such that they still could be switched and characterized electrically after the preparation. The result of these observations in comparison with detailed electrical characterization showed (i) normal behavior for relatively long amorphous marks, resulting in a hyperbolic dependence between SET resistance and SET current, indicating a switching mechanism based on initially long and thin nanoscale crystalline filaments which thicken gradually, and (ii) anomalous behavior, which holds for relatively short amorphous marks, where initially directly a massive crystalline filament is formed that consumes most of the width of the amorphous mark only leaving minor residual amorphous regions at its edges. The present results demonstrate that even in (purposely) thick TEM samples, the TEM sample preparation hampers the probability to observe normal behavior and it can be debated whether it is possible to produce electrically switchable TEM specimen in which the memory cells behave the same as in their original bulk embedded state.

  13. Chronic restricted access to 10% sucrose solution in adolescent and young adult rats impairs spatial memory and alters sensitivity to outcome devaluation.

    PubMed

    Kendig, Michael D; Boakes, Robert A; Rooney, Kieron B; Corbit, Laura H

    2013-08-15

    Although increasing consumption of sugar drinks is recognized as a significant public health concern, little is known about (a) the cognitive effects resulting from sucrose consumption; and (b) whether the long-term effects of sucrose consumption are more pronounced for adolescents. This experiment directly compared performance on a task of spatial learning and memory (the Morris Water Maze) and sensitivity to outcome devaluation following 28 days of 2-h/day access to a 10% sucrose solution in adolescent and young-adult Wistar rats. Sucrose groups developed elevated fasting blood glucose levels after the diet intervention, despite drawing <15% of calories from sucrose and gaining no more weight than controls. In subsequent behavioral testing, sucrose groups were impaired on the Morris Water Maze, with some residual deficits in spatial memory observed more than 6 weeks after the end of sucrose exposure. Further, results from outcome devaluation testing indicated that in the older cohort of rats, those fed sucrose showed reduced sensitivity to devaluation of the outcome, suggestive of differences in instrumental learning following sucrose exposure. Data provide strong evidence that sucrose consumption can induce deficits in spatial cognition and reward-oriented behavior at levels that resemble patterns of sugar drink consumption in young people, and which can remain long after exposure. PMID:23954407

  14. Basic Performance of a Logic Intellectual Property Compatible Embedded Dynamic Random Access Memory with Cylinder Capacitors in Low-k/Cu Back End on the Line Layers

    NASA Astrophysics Data System (ADS)

    Kume, Ippei; Inoue, Naoya; Hijioka, Ken'ichiro; Kawahara, Jun; Takeda, Kouichi; Furutake, Naoya; Shirai, Hiroki; Kazama, Kenya; Kuwabara, Shin'ichi; Watarai, Msasatoshi; Sakoh, Takashi; Takahashi, Takafumi; Ogura, Takashi; Taiji, Toshiji; Kasama, Yoshiko; Sakamoto, Misato; Hane, Masami; Hayashi, Yoshihiro

    2012-02-01

    We have confirmed the basic performance of a new logic intellectual property (IP) compatible (LIC) embedded dynamic random access memory (eDRAM) with cylinder capacitors in the low-k/Cu back end on the line (BEOL) layers. The LIC-eDRAM reduces the contact (CT) height, or essentially the RC delays due to the parasitic component to the contact. By circuit simulation, a 28-nm-node LIC-eDRAM with the reduced CT height controls the logic delay with Δτd < 5% to that of 28-nm-node standard complementary metal oxide semiconductor (CMOS) logics, enabling us ensure the logic IP compatibility. This was confirmed also by a 40-nm-node LIC-eDRAM test-chip fabricated. The 40-nm-node inverter delays in the test-chip were controlled actually within Δτd < 5%, referred to those of a pure-CMOS logic LSI. Meanwhile the retention time of the DRAM macro was in the range of milliseconds, which has no difference to that of a conventional eDRAM with a capacitor-on-bitline (COB) structure. The LIC-eDRAM is one type of BEOL memory on standard CMOS devices, and is sustainable for widening eDRAM applications combined with a variety of leading-edge CMOS logic IPs, especially beyond 28-nm-nodes.

  15. On the robustness of bucket brigade quantum RAM

    NASA Astrophysics Data System (ADS)

    Arunachalam, Srinivasan; Gheorghiu, Vlad; Jochym-O'Connor, Tomas; Mosca, Michele; Varshinee Srinivasan, Priyaa

    2015-12-01

    We study the robustness of the bucket brigade quantum random access memory model introduced by Giovannetti et al (2008 Phys. Rev. Lett.100 160501). Due to a result of Regev and Schiff (ICALP ’08 733), we show that for a class of error models the error rate per gate in the bucket brigade quantum memory has to be of order o({2}-n/2) (where N={2}n is the size of the memory) whenever the memory is used as an oracle for the quantum searching problem. We conjecture that this is the case for any realistic error model that will be encountered in practice, and that for algorithms with super-polynomially many oracle queries the error rate must be super-polynomially small, which further motivates the need for quantum error correction. By contrast, for algorithms such as matrix inversion Harrow et al (2009 Phys. Rev. Lett.103 150502) or quantum machine learning Rebentrost et al (2014 Phys. Rev. Lett.113 130503) that only require a polynomial number of queries, the error rate only needs to be polynomially small and quantum error correction may not be required. We introduce a circuit model for the quantum bucket brigade architecture and argue that quantum error correction for the circuit causes the quantum bucket brigade architecture to lose its primary advantage of a small number of ‘active’ gates, since all components have to be actively error corrected.

  16. The role of internal structure in the anomalous switching dynamics of metal-oxide/polymer resistive random access memories

    NASA Astrophysics Data System (ADS)

    Rocha, Paulo R. F.; Kiazadeh, Asal; De Leeuw, Dago M.; Meskers, Stefan C. J.; Verbakel, Frank; Taylor, David M.; Gomes, Henrique L.

    2013-04-01

    The dynamic response of a non-volatile, bistable resistive memory fabricated in the form of Al2O3/polymer diodes has been probed in both the off- and on-state using triangular and step voltage profiles. The results provide insight into the wide spread in switching times reported in the literature and explain an apparently anomalous behaviour of the on-state, namely the disappearance of the negative differential resistance region at high voltage scan rates which is commonly attributed to a "dead time" phenomenon. The off-state response follows closely the predictions based on a classical, two-layer capacitor description of the device. As voltage scan rates increase, the model predicts that the fraction of the applied voltage, Vox, appearing across the oxide decreases. Device responses to step voltages in both the off- and on-state show that switching events are characterized by a delay time. Coupling such delays to the lower values of Vox attained during fast scan rates, the anomalous observation in the on-state that, device currents decrease with increasing voltage scan rate, is readily explained. Assuming that a critical current is required to turn off a conducting channel in the oxide, a tentative model is suggested to explain the shift in the onset of negative differential resistance to lower voltages as the voltage scan rate increases. The findings also suggest that the fundamental limitations on the speed of operation of a bilayer resistive memory are the time- and voltage-dependences of the switch-on mechanism and not the switch-off process.

  17. Retracing Memories

    ERIC Educational Resources Information Center

    Harrison, David L.

    2005-01-01

    There are plenty of paths to poetry but few are as accessible as retracing ones own memories. When students are asked to write about something they remember, they are given them the gift of choosing from events that are important enough to recall. They remember because what happened was funny or scary or embarrassing or heartbreaking or silly.…

  18. Flexible and stackable non-volatile resistive memory for high integration

    NASA Astrophysics Data System (ADS)

    Ali, Shawkat; Bae, Jinho; Lee, Chong Hyun

    2015-08-01

    We propose a novel flexible and stackable resistive random access memory (ReRAM) array with multi-layered crossbar structures fabricated on a PET flexible substrate through EHD system. The basic memory block of the proposed device is based on one resistor and multi-layered column memristors (1R-MCM) structure, which can be easily extended to 3 dimensional columns for a high integration. To fabricate the device, the materials Ag for top and bottom electrodes, PVP for memristor, and (MEH:PPV and PMMA in acetonitrile) for pull-up resistors are used. Memory single cell is consisted of a high OFF/ON ratio (~4663) memristor and a pull-up resistor (20 MΩ) that operate on the principles of voltage divider circuit. Memory logic data is retrieve in the form of voltage levels instead of sensing current the of crossbar array. Two memory crossbar arrays are stacked vertically and they are sharing column bars, each column's memristors are with a single pull-up resistor. A 3x3 stacked memory with two layers that can store 18 bits of data is demonstrated to realize on a small area for a high integration.

  19. Ram-Jet off Design Performances

    NASA Astrophysics Data System (ADS)

    Andriani, Roberto; Ghezzi, Umberto

    2002-01-01

    In this work it is intended to study the off-design performances of a ram jet engine. To this purpouse it has been analyzed in a first time the behaviour of an ideal engine, that means to not consider the losses in the various components, or, under a thermodynamic point of view, to consider the fluid transformation through the air intake and exhaust nozzle, remembering that in a ram jet there are not rotating components as compressor and turbine, isentropic. Referring to the ram-jet scheme of fig.1. we can say, neglecting the fuel introduced, that the air mass flow rate throughout the engine is constant. If we consider the two control sections 4 and 8, respectively the throat section of the converging-diverging supersonic inlet and the throat section of the discharge nozzle, the condition of constant mass flow leads to the relation: m4 =f (M 4 ) m8 = m 4 = m8 We can imaging that the throat section # 4 is always choked for any value of the flight Mach number M0. This means that the throat section 4 is adjusted at any value of M0 so that the flow Mach number in 4 is equal to unity. In this it follows: R. Andriani, U. Ghezzi1 Since in an ideal case T t8 The relation [1] allows to determine the T8 temperature, that represent the maximum cycle temperature, for different operating conditions, as flight Mach number and altitude. We then have two cases: the first is A8 (nozzle throat section) fixed, and the second is A8 variable. In the first case the maximum temperature T8 is univocally determined by the operating condition. In the second case A8 can be varied so to maintain T8 at a chosen value. The graphic of fig.2 shows the first case. In particular it has been considered as design point an altitude of 15000 meters and a flight Mach number equal to 2. In this condition it has been evaluated the section A8 for unity mass flow rate. At the same altitude, varying the flight Mach number, with the section A4 always choked, the graphic shows the variation of the maximum

  20. Magnetic bubble domain memories

    NASA Technical Reports Server (NTRS)

    Ypma, J. E.

    1974-01-01

    Some attractive features of Bubble Domain Memory and its relation to existing technologies are discussed. Two promising applications are block access mass memory and tape recorder replacement. The required chip capabilities for these uses are listed, and the specifications for a block access mass memory designed to fit between core and HPT disk are presented. A feasibility model for a tape recorder replacement is introduced.

  1. 26. EASTERNMOST HYDRAULIC RAM IN CENTER RANK (STILL OPERABLE), LOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. EASTERNMOST HYDRAULIC RAM IN CENTER RANK (STILL OPERABLE), LOWER LEVEL OF STAGE, LOOKING SOUTH. THE CENTER BANK OF RAMS MOVED SMALL SECTIONS OF STAGE IN THE CENTER OF EACH LARGE MOVABLE SECTION. THE WEST EDGE OF THIS SECTION HAS BEEN EXTENDED TO THE WEST EDGE OF THE LARGE SECTION WHICH ORIGINALLY SURROUNDED IT. THE SOUTH RAM FOR THE LARGE SECTION IS VISIBLE IN THE BACKGROUND. THE SMALL MOVABLE SECTIONS COULD NOT TILT BUT COULD BE LOWERED TO THE LOWER LEVEL OF THE STAGE WITH HINGED PANELS UNDER EACH LARGE SECTION FILLING THE VOID. - Auditorium Building, 430 South Michigan Avenue, Chicago, Cook County, IL

  2. Ram pressure stripping in the Virgo Cluster

    NASA Astrophysics Data System (ADS)

    Verdugo, C.; Combes, F.; Dasyra, K.; Salomé, P.; Braine, J.

    2015-10-01

    Gas can be violently stripped from their galaxy disks in rich clusters, and be dispersed over 100 kpc-scale tails or plumes. Young stars have been observed in these tails, suggesting they are formed in situ. This will contribute to the intracluster light, in addition to tidal stripping of old stars. We want to quantify the efficiency of intracluster star formation. We present CO(1-0) and CO(2-1) observations, made with the IRAM-30 m telescope, towards the ram-pressure stripped tail northeast of NGC 4388 in Virgo. We selected HII regions found all along the tails, together with dust patches, as observing targets. We detect molecular gas in 4 positions along the tail, with masses between 7 × 105 to 2 × 106M⊙. Given the large distance from the NGC 4388 galaxy, the molecular clouds must have formed in situ, from the HI gas plume. We compute the relation between surface densities of star formation and molecular gas in these regions, and find that the star formation has very low efficiency. The corresponding depletion time of the molecular gas can be up to 500 Gyr and more. Since this value exceeds a by far Hubble time, this gas will not be converted into stars, and will stay in a gaseous phase to join the intracluster medium.

  3. New River Geothermal Exploration (Ram Power Inc.)

    DOE Data Explorer

    Miller, Clay

    2013-11-15

    The New River Geothermal Exploration (DOE Award No. EE0002843) is located approximately 25km south of the Salton Sea, near town of Brawley in Imperial County and approximately 150km east of San Diego, California. A total of 182 MT Logger sites were completed covering the two separate Mesquite and New River grids. The data was collected over a frequency range of 320Hz to 0.001Hz with variable site spacing. A number of different inversion algorithms in 1D, 2D and 3D were used to produce resistivity-depth profiles and maps of subsurface resistivity variations over the survey area. For 2D inversions, a total of eighteen lines were constructed in east-west and north-south orientations crossing the entire survey area. For MT 3D inversion, the New River property was divided in two sub-grids, Mesquite and New River areas. The report comprises of two parts. For the first part, inversions and geophysical interpretation results are presented with some recommendations of the potential targets for future follow up on the property. The second part of the report describes logistics of the survey, survey parameters, methodology and the survey results (data) in digital documents. The report reviews a Spartan MT survey carried out by Quantec Geoscience Limited over the New River Project in California, USA on behalf of Ram Power Inc. Data was acquired over a period of 29 days from 2010/06/26 to 2010/07/24.

  4. Retention modeling for ultra-thin density of Cu-based conductive bridge random access memory (CBRAM)

    NASA Astrophysics Data System (ADS)

    Aga, Fekadu Gochole; Woo, Jiyong; Lee, Sangheon; Song, Jeonghwan; Park, Jaesung; Park, Jaehyuk; Lim, Seokjae; Sung, Changhyuck; Hwang, Hyunsang

    2016-02-01

    We investigate the effect of Cu concentration On-state resistance retention characteristics of W/Cu/Ti/HfO2/Pt memory cell. The development of RRAM device for application depends on the understanding of the failure mechanism and the key parameters for device optimization. In this study, we develop analytical expression for cations (Cu+) diffusion model using Gaussian distribution for detailed analysis of data retention time at high temperature. It is found that the improvement of data retention time depends not only on the conductive filament (CF) size but also on Cu atoms concentration density in the CF. Based on the simulation result, better data retention time is observed for electron wave function associated with Cu+ overlap and an extended state formation. This can be verified by analytical calculation of Cu atom defects inside the filament, based on Cu+ diffusion model. The importance of Cu diffusion for the device reliability and the corresponding local temperature of the filament were analyzed by COMSOL Multiphysics simulation.

  5. Control over variability in nonvolatile hafnium-oxide resistive-switching memory based on modeling of the switching processes

    NASA Astrophysics Data System (ADS)

    Butcher, Brian Jerad

    Resistive random access memory (ReRAM) technology presents an attractive option for embedded non-volatile (NV) memory systems if its variability (cycle-to-cycle and device-to-device) can be controlled. This dissertation has focused on investigations to identify key mechanisms and parameters which dominate ReRAM variability, and the development of subsequent experimental and simulation-based tools to address this variability. The first component of these efforts entailed identification of the modern-day non-volatile memory technological gaps that have driven the operational requirements and challenges for resistive memory as an emerging NV memory. Initial research confirmed the critical requirement of a sub-stoichiometric (HfO2-x) dielectric regarding the enablement of stable switching and suggested a defect-driven mechanism, which is discussed in detail. Preliminary experimental work was focused on the fabrication of a durable current-limiting (1T1R) testing structure; which was utilized to enable ReRAM device characterization, reduce unwanted parasitic capacitances, and overshoot-current. Initial electrical and physical characterization confirmed a filamentary based (defect-driven) mechanism based on ReRAM scalability-trends (in device sizes ranging from 50x50nm2 to 7x7microm2). Physical analysis (AFM, TEM and EELS) verified a `dominant-filament mechanism' in transmission-metal-oxide (specifically HfO2-x) based ReRAM. A novel characterization and analysis protocol for key electrical parameters affecting filament formation for HfO2-x-based ReRAMs was developed, focusing on the roles of current, voltage, and temperature. This protocol included characterization of the high-resistive-state (HRS) dependence on the maximum FORMING current (seen during 1st RESET Imax) and the characterization of low-power endurance. This characterization protocol was employed to investigate and develop an approach for ReRAM filament formation at elevated temperatures (hot FORMING) to

  6. Reproducible resistive switching in nonstoichiometric nickel oxide films grown by rf reactive sputtering for resistive random access memory applications

    SciTech Connect

    Park, Jae-Wan; Park, Jong-Wan; Kim, Dal-Young; Lee, Jeon-Kook

    2005-09-15

    Ni{sub 1-{delta}}O binary oxide films were deposited on Pt/Ti/SiO{sub 2}/Si substrates by radio-frequency reactive magnetron sputtering. The NiO-based metal-oxide-metal structures were fabricated for measurement of electrical properties. The electrical properties of the Pt/Ni{sub 1-{delta}}O/Pt structure as a function of growth temperature were investigated. The growth temperature was varied from room temperature to 400 deg. C. From all samples, negative resistance phenomenon and nonvolatile memory switching behavior were observed. The ratios between the high-resistance state (OFF state) and the low-resistance state (ON state) were larger than. 10{sup 2}. As the growth temperature was increased, both SET and RESET voltages increased due to the decrease of defects in nickel oxide films. On the basis of x-ray diffraction patterns, we confirmed that the defects in Ni{sub 1-{delta}}O film decreased with increasing the growth temperature due to sufficient diffusion and redistribution of adatoms. X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy analysis revealed that the nickel oxide films were Ni deficient and that Ni had three different Ni bond states caused by various defects in nickel oxide films. In order to investigate the influence of the upper limit of SET current (i.e., Compliance SET current), the compliance SET current was varied from 1 to 50 mA. This result showed that the ON-state current and the RESET voltage were strongly dependent on the magnitude of the compliance SET current. As the compliance SET current was increased, both the ON-state current and the RESET voltage increased due to the increase of the conducting path. The results suggest that the resistance switching behavior is related to the formation and fracture of the conducting path which is composed of defects in the nickel oxide film.

  7. 10. DETAIL OF CORNICE MOULDING WITH RAM'S HEAD MOTIF. EIGHT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. DETAIL OF CORNICE MOULDING WITH RAM'S HEAD MOTIF. EIGHT SHADES OF GOLD LEAF AND BURNISHED GOLD LEAF WERE USED FOR THE INTERIOR FINISHES - Anaconda Historic District, Washoe Theater, 305 Main Street, Anaconda, Deer Lodge County, MT

  8. DETAIL OF CORNICE MOULDING WITH RAM'S HEAD MOTIF. EIGHT SHADES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL OF CORNICE MOULDING WITH RAM'S HEAD MOTIF. EIGHT SHADES OF GOLD LEAF AND BURNISHED GOLD LEAF WERE USED FOR THE INTERIOR FINISHES. - Anaconda Historic District, Washoe Theater, 305 Main Street, Anaconda, Deer Lodge County, MT

  9. RAM simulation model for SPH/RSV systems

    SciTech Connect

    Schryver, J.C.; Primm, A.H.; Nelson, S.C.

    1995-12-31

    The US Army`s Project Manager, Crusader is sponsoring the development of technologies that apply to the Self-Propelled Howitzer (SPH), formerly the Advanced Field Artillery System (AFAS), and Resupply Vehicle (RSV), formerly the Future Armored Resupply Vehicle (FARV), weapon system. Oak Ridge National Laboratory (ORNL) is currently performing developmental work in support of the SPH/PSV Crusader system. Supportive analyses of reliability, availability, and maintainability (RAM) aspects were also performed for the SPH/RSV effort. During FY 1994 and FY 1995 OPNL conducted a feasibility study to demonstrate the application of simulation modeling for RAM analysis of the Crusader system. Following completion of the feasibility study, a full-scale RAM simulation model of the Crusader system was developed for both the SPH and PSV. This report provides documentation for the simulation model as well as instructions in the proper execution and utilization of the model for the conduct of RAM analyses.

  10. Magnetic content addressable memories

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenye

    Content Addressable Memories are designed with comparison circuits built into every bit cell. This parallel structure can increase the speed of searching from O(n) (as with Random Access Memories) to O(1), where n is the number of entries being searched. The high cost in hardware limits the application of CAM within situations where higher searching speed is extremely desired. Spintronics technology can build non-volatile Magnetic RAM with only one device for one bit cell. There are various technologies involved, like Magnetic Tunnel Junctions, off-easy-axis programming method, Synthetic Anti-Ferromagnetic tri-layers, Domain Wall displacement, Spin Transfer Torque tri-layers and etc. With them, particularly the Tunnel Magneto-Resistance variation in MTJ due to difference in magnetization polarity of the two magnets, Magnetic CAM can be developed with reduced hardware cost. And this is demonstrated by the discussion in this dissertation. Six MCAM designs are discussed. In the first design, comparand (C), local information (S) and their complements are stored into 4 MTJs connected in XOR gate pattern. The other five designs have one or two stacks for both information storage and comparison, and full TMR ratio can be taken advantage of. Two challenges for the five are specifically programming C without changing S and selectively programming a cell out of an array. The solutions to specific programming are: by confining the programming field for C in a ring structure design; by using field programming and spin polarized current programming respectively for C and S in the SAF+DW and SAF+STT tri-layer design; by making use of the difference in thresholds between direct mode and toggle mode switching in the SAF+SAF design. The problem of selective programming is addressed by off-easy-axis method and by including SAF tri-layers. Cell with STT tri-layers for both C and S can completely avoid the problems of specific and selective programming, but subject to the limit of

  11. [Artificial intelligence meeting neuropsychology. Semantic memory in normal and pathological aging].

    PubMed

    Aimé, Xavier; Charlet, Jean; Maillet, Didier; Belin, Catherine

    2015-03-01

    Artificial intelligence (IA) is the subject of much research, but also many fantasies. It aims to reproduce human intelligence in its learning capacity, knowledge storage and computation. In 2014, the Defense Advanced Research Projects Agency (DARPA) started the restoring active memory (RAM) program that attempt to develop implantable technology to bridge gaps in the injured brain and restore normal memory function to people with memory loss caused by injury or disease. In another IA's field, computational ontologies (a formal and shared conceptualization) try to model knowledge in order to represent a structured and unambiguous meaning of the concepts of a target domain. The aim of these structures is to ensure a consensual understanding of their meaning and a univariant use (the same concept is used by all to categorize the same individuals). The first representations of knowledge in the AI's domain are largely based on model tests of semantic memory. This one, as a component of long-term memory is the memory of words, ideas, concepts. It is the only declarative memory system that resists so remarkably to the effects of age. In contrast, non-specific cognitive changes may decrease the performance of elderly in various events and instead report difficulties of access to semantic representations that affect the semantics stock itself. Some dementias, like semantic dementia and Alzheimer's disease, are linked to alteration of semantic memory. We propose in this paper, using the computational ontologies model, a formal and relatively thin modeling, in the service of neuropsychology: 1) for the practitioner with decision support systems, 2) for the patient as cognitive prosthesis outsourced, and 3) for the researcher to study semantic memory. PMID:25786428

  12. 33 CFR 147.811 - Ram-Powell Tension Leg Platform safety zone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Ram-Powell Tension Leg Platform... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.811 Ram-Powell Tension Leg Platform safety zone. (a) Description. The Ram-Powell Tension Leg Platform (Ram-Powell TLP) is located...

  13. 33 CFR 147.811 - Ram-Powell Tension Leg Platform safety zone.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Ram-Powell Tension Leg Platform... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.811 Ram-Powell Tension Leg Platform safety zone. (a) Description. The Ram-Powell Tension Leg Platform (Ram-Powell TLP) is located...

  14. 33 CFR 147.811 - Ram-Powell Tension Leg Platform safety zone.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Ram-Powell Tension Leg Platform... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.811 Ram-Powell Tension Leg Platform safety zone. (a) Description. The Ram-Powell Tension Leg Platform (Ram-Powell TLP) is located...

  15. 33 CFR 147.811 - Ram-Powell Tension Leg Platform safety zone.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Ram-Powell Tension Leg Platform... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.811 Ram-Powell Tension Leg Platform safety zone. (a) Description. The Ram-Powell Tension Leg Platform (Ram-Powell TLP) is located...

  16. 33 CFR 147.811 - Ram-Powell Tension Leg Platform safety zone.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Ram-Powell Tension Leg Platform... SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.811 Ram-Powell Tension Leg Platform safety zone. (a) Description. The Ram-Powell Tension Leg Platform (Ram-Powell TLP) is located...

  17. High-performance ferroelectric memory based on fully patterned tunnel junctions

    NASA Astrophysics Data System (ADS)

    Boyn, S.; Girod, S.; Garcia, V.; Fusil, S.; Xavier, S.; Deranlot, C.; Yamada, H.; Carrétéro, C.; Jacquet, E.; Bibes, M.; Barthélémy, A.; Grollier, J.

    2014-02-01

    In tunnel junctions with ferroelectric barriers, switching the polarization direction modifies the electrostatic potential profile and the associated average tunnel barrier height. This results in strong changes of the tunnel transmission and associated resistance. The information readout in ferroelectric tunnel junctions (FTJs) is thus resistive and non-destructive, which is an advantage compared to the case of conventional ferroelectric memories (FeRAMs). Initially, endurance limitation (i.e., fatigue) was the main factor hampering the industrialization of FeRAMs. Systematic investigations of switching dynamics for various ferroelectric and electrode materials have resolved this issue, with endurance now reaching 1014 cycles. Here we investigate data retention and endurance in fully patterned submicron Co/BiFeO3/Ca0.96Ce0.04MnO3 FTJs. We report good reproducibility with high resistance contrasts and extend the maximum reported endurance of FTJs by three orders of magnitude (4 × 106 cycles). Our results indicate that here fatigue is not limited by a decrease of the polarization or an increase of the leakage but rather by domain wall pinning. We propose directions to access extreme and intermediate resistance states more reliably and further strengthen the potential of FTJs for non-volatile memory applications.

  18. Resistive switching characteristics of HfO2-based memory devices on flexible plastics.

    PubMed

    Han, Yong; Cho, Kyoungah; Park, Sukhyung; Kim, Sangsig

    2014-11-01

    In this study, we examine the characteristics of HfO2-based resistive switching random access memory (ReRAM) devices on flexible plastics. The Pt/HfO2/Au ReRAM devices exhibit the unipolar resistive switching behaviors caused by the conducting filaments. From the Auger depth profiles of the HfO2 thin film, it is confirmed that the relatively lower oxygen content in the interface of the bottom electrode is responsible for the resistive switching by oxygen vacancies. And the unipolar resistive switching behaviors are analyzed from the C-V characteristics in which negative and positive capacitances are measured in the low-resistance state and the high-resistance state, respectively. The devices have a high on/off ratio of 10(4) and the excellent retention properties even after a continuous bending test of two thousand cycles. The correlation between the device size and the memory characteristics is investigated as well. A relatively smaller-sized device having a higher on/off ratio operates at a higher voltage than a relatively larger-sized device. PMID:25958498

  19. Residual Clamping Force and Dynamic Random Access Memory Data Retention Improved by Gate Tungsten Etch Dechucking Condition in a Bipolar Electrostatic Chuck

    NASA Astrophysics Data System (ADS)

    Lee, Chung-Yuan; Lai, Chao-Sung; Yang, Chia-Ming; Wang, David HL; Lin, Betty; Lee, Siimon; Huang, Chi-Hung; Wei, Chen Chang

    2012-08-01

    It was found that the residual clamping force of bipolar electrostatic chucks created by the residual charge between a wafer and an electrode would not only cause a wafer sticking problem but also degrade dynamic random access memory (DRAM) data retention performance. The residual clamping force and data retention fail bit count (FBC) of DRAM showed strong correlations to the gate tungsten etch dechucking process condition. Wafer sticking only degraded DRAM cell retention performance, and did not influence any in-line measurement or electrical parameters. Electrical characterization analysis of the FBC proved that the retention loss was mainly due to junction leakage rather than gate-induced-drain-leakage current. A new approach was proposed to suppress this leakage by introducing N2 gas instead of O2 to supply more plasma charges for neutralizing the wafer surface residual charges. The wafer shift dynamic alignment (DA) offset and retention FBC could be reduced by 50 and 40%, respectively. Poor data retention was suspected because of the compressive stress caused by wafer sticking DA shift resulting in a high electric field at the junction and an increase in junction leakage at the storage node.

  20. Power- and Low-Resistance-State-Dependent, Bipolar Reset-Switching Transitions in SiN-Based Resistive Random-Access Memory.

    PubMed

    Kim, Sungjun; Park, Byung-Gook

    2016-12-01

    A study on the bipolar-resistive switching of an Ni/SiN/Si-based resistive random-access memory (RRAM) device shows that the influences of the reset power and the resistance value of the low-resistance state (LRS) on the reset-switching transitions are strong. For a low LRS with a large conducting path, the sharp reset switching, which requires a high reset power (>7 mW), was observed, whereas for a high LRS with small multiple-conducting paths, the step-by-step reset switching with a low reset power (<7 mW) was observed. The attainment of higher nonlinear current-voltage (I-V) characteristics in terms of the step-by-step reset switching is due to the steep current-increased region of the trap-controlled space charge-limited current (SCLC) model. A multilevel cell (MLC) operation, for which the reset stop voltage (V STOP) is used in the DC sweep mode and an incremental amplitude is used in the pulse mode for the step-by-step reset switching, is demonstrated here. The results of the present study suggest that well-controlled conducting paths in a SiN-based RRAM device, which are not too strong and not too weak, offer considerable potential for the realization of low-power and high-density crossbar-array applications. PMID:27518231

  1. Correlation of anomalous write error rates and ferromagnetic resonance spectrum in spin-transfer-torque-magnetic-random-access-memory devices containing in-plane free layers

    SciTech Connect

    Evarts, Eric R.; Rippard, William H.; Pufall, Matthew R.; Heindl, Ranko

    2014-05-26

    In a small fraction of magnetic-tunnel-junction-based magnetic random-access memory devices with in-plane free layers, the write-error rates (WERs) are higher than expected on the basis of the macrospin or quasi-uniform magnetization reversal models. In devices with increased WERs, the product of effective resistance and area, tunneling magnetoresistance, and coercivity do not deviate from typical device properties. However, the field-swept, spin-torque, ferromagnetic resonance (FS-ST-FMR) spectra with an applied DC bias current deviate significantly for such devices. With a DC bias of 300 mV (producing 9.9 × 10{sup 6} A/cm{sup 2}) or greater, these anomalous devices show an increase in the fraction of the power present in FS-ST-FMR modes corresponding to higher-order excitations of the free-layer magnetization. As much as 70% of the power is contained in higher-order modes compared to ≈20% in typical devices. Additionally, a shift in the uniform-mode resonant field that is correlated with the magnitude of the WER anomaly is detected at DC biases greater than 300 mV. These differences in the anomalous devices indicate a change in the micromagnetic resonant mode structure at high applied bias.

  2. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition.

    PubMed

    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. Investigation of Cr0.06(Sb4Te)0.94 alloy for high-speed and high-data-retention phase change random access memory applications

    NASA Astrophysics Data System (ADS)

    Li, Le; Song, Sannian; Zhang, Zhonghua; Song, Zhitang; Cheng, Yan; Lv, Shilong; Wu, Liangcai; Liu, Bo; Feng, Songlin

    2015-08-01

    The effects of Cr doping on the structural and electrical properties of Cr x (Sb4Te)1- x materials have been investigated in order to solve the contradiction between thermal stability and fast crystallization speed of Sb4Te alloys. Cr0.06(Sb4Te)0.94 alloy is considered to be a potential candidate for phase change random access memory (PCM), as evidenced by a higher crystallization temperature (204 °C), a better data retention ability (137.6 °C for 10 years), a lower melting point (558 °C), a lower energy consumption, and a faster switching speed in comparison with those of Ge2Sb2Te5. A reversible switching between set and reset states can be realized by an electric pulse as short as 5 ns for Cr0.06(Sb4Te)0.94-based PCM cell. In addition, Cr0.06(Sb4Te)0.94 shows good endurance up to 1.1 × 104 cycles with a resistance ratio of about two orders of magnitude.

  4. Highly Reliable 0.15 μm/14 F2 Cell Ferroelectric Random Access Memory Capacitor Using SrRuO3 Buffer Layer

    NASA Astrophysics Data System (ADS)

    Heo, Jang‑Eun; Bae, Byoung‑Jae; Yoo, Dong‑Chul; Nam, Sang‑Don; Lim, Ji‑Eun; Im, Dong‑Hyun; Joo, Suk‑Ho; Jung, Yong‑Ju; Choi, Suk‑Hun; Park, Soon‑Oh; Kim, Hee‑Seok; Chung, U‑In; Moon, Joo‑Tae

    2006-04-01

    We investigated a novel technique of modifying the interface between a Pb(ZrxTi1-x)O3 (PZT) thin film and electrodes for high density 64 Mbit ferroelectric random access memory (FRAM) device. Using a SrRuO3 buffer layer, we successfully developed highly reliable 0.15 μm/14 F2 cell FRAM capacitors with 75-nm-thick polycrystalline PZT thin films. The SrRuO3 buffer layer greatly enhanced ferroelectric characteristics due to the decrease in interfacial defect density. In PZT capacitors with a total thickness of 180 nm for whole capacitor stack, a remnant polarization of approximately 42 μC/cm2 was measured with a 1.4 V operation. In addition, an opposite state remnant polarization loss of less than 15% was observed after baking at 150 °C for 100 h. In particular, we found that the SrRuO3 buffer layer also played a key role in inhibiting the diffusion of Pb and O from the PZT thin films.

  5. Integration and Electrical Properties of Novel Ferroelectric Capacitors for 0.25 μm 1 Transistor 1 Capacitor Ferroelectric Random Access Memory (1T1C FRAM)

    NASA Astrophysics Data System (ADS)

    Song, Y. J.; Jang, N. W.; Jung, D. J.; Kim, H. H.; Joo, H. J.; Lee, S. Y.; Lee, K. M.; Joo, S. H.; Park, S. O.; Kim, Kinam

    2002-04-01

    Since the space margin between capacitors has been greatly reduced in 32 Mb high-density ferroelectric random access memory (FRAM) with a 0.25 μm design rule, considering the limitation of current etching technology, the stack height of ferroelectric capacitors should be minimized for stable node separation. In this paper, novel capacitors with a total thickness of 4000 Å were prepared using a seeding layer, low temperature processing, and optimal top electrode annealing. The 1000 Å Pb(Zr1-xTix)O3 (PZT) films showed excellent structural and ferroelectric properties such as strong (111) orientation and large remanent polarization of 40 μC/cm2. The low stack capacitors were then implemented into 0.6 μm and prototype 0.25 μm FRAM. Compared to a conventional capacitor stack, the ferroelectric capacitors exhibited adequate sensing margin of 250 fC, thus giving rise to a fully working die of 4 Mb FRAM. Therefore, it was clearly demonstrated that the novel capacitors can enable the realization of a high-density 32 Mb FRAM device with a 0.25 μm design rule.

  6. Plasma-Assisted Dry Etching of Ferroelectric Capacitor Modules and Application to a 32M Ferroelectric Random Access Memory Devices with Submicron Feature Sizes

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Woo; Joo, Suk-Ho; Cho, Sung Lae; Son, Yoon-Ho; Lee, Kyu-Mann; Nam, Sang-Don; Park, Kun-Sang; Lee, Yong-Tak; Seo, Jung-Suk; Kim, Young-Dae; An, Hyeong-Geun; Kim, Hyoung-Joon; Jung, Yong-Ju; Heo, Jang-Eun; Lee, Moon-Sook; Park, Soon-Oh; Chung, U-In; Moon, Joo-Tae

    2002-11-01

    In the manufacturing of a 32M ferroelectric random access memory (FRAM) device on the basis of 0.25 design rule (D/R), one of the most difficult processes is to pattern a submicron capacitor module while retaining good ferroelectric properties. In this paper, we report the ferroelectric property of patterned submicron capacitor modules with a stack height of 380 nm, where the 100 nm-thick Pb(Zr, Ti)O3 (PZT) films were prepared by the sol-gel method. After patterning, overall sidewall slope was approximately 70° and cell-to-cell node separation was made to be 80 nm to prevent possible twin-bit failure in the device. Finally, several heat treatment conditions were investigated to retain the ferroelectric property of the patterned capacitor. It was found that rapid thermal processing (RTP) treatment yields better properties than conventional furnace annealing. This result is directly related to the near-surface chemistry of the PZT films, as confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The resultant switching polarization value of the submicron capacitor was approximately 30 μC/cm2 measured at 3 V.

  7. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition

    NASA Astrophysics Data System (ADS)

    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.

  8. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition

    PubMed Central

    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

  9. Interfacial Electrode-Driven Enhancement of the Switching Parameters of a Copper Oxide-Based Resistive Random-Access Memory Device

    NASA Astrophysics Data System (ADS)

    Sangani, L. D. Varma; Kumar, Ch. Ravi; Krishna, M. Ghanashyam

    2016-01-01

    The characteristics of an Au/Cu x O/Au bipolar resistive random-access memory device are reported. It is demonstrated that switching parameters of this device structure can be enhanced by introducing an interfacial Al layer between the Au top electrode and the Cu x O-based dielectric layer. The set and reset voltages are, respectively, between -2.5 V to -6.0 V and +1.2 V to +3.0 V for the Al-based device. In contrast, the range of values are -0.5 V to -2.5 V and +0.5 V to +1.5 V for the set and reset voltages in the absence of Al. The Al-based device has a higher low resistance state value of 5-6 KΩ as compared to the 0.3-0.5 KΩ for the Au-based device, which leads to a 12 times lower power dissipation factor and lower reset current of 370 μA. Endurance studies carried out over 50 switching cycles show less than 2% variation in both the low resistance and high resistance values. The conduction is ohmic at low values of bias and non-ohmic at higher bias voltage which shows that the enhanced behaviour is a result of the formation of an insulating aluminum oxide layer at the Al-Cu x O interface.

  10. Resistive switching and electrical control of ferromagnetism in a Ag/HfO₂/Nb:SrTiO₃/Ag resistive random access memory (RRAM) device at room temperature.

    PubMed

    Ren, Shaoqing; Zhu, Gengchang; Xie, Jihao; Bu, Jianpei; Qin, Hongwei; Hu, Jifan

    2016-02-10

    Electrically induced resistive switching and modulated ferromagnetism are simultaneously found in a Ag/HfO2/Nb:SrTiO3/Ag resistive random access memory device at room temperature. The bipolar resistive switching (RS) can be controlled by the modification of a Schottky-like barrier with an electron injection-trapped/detrapped process at the interface of HfO2-Nb:SrTiO3. The multilevel RS transition can be observed in the reset process with larger negative voltage sweepings, which is connected to the different degree of electron detrapping in the interfacial depletion region of the HfO2 layer during the reset process. The origin of the electrical control of room-temperature ferromagnetism may be connected to the change of density of oxygen vacancies in the HfO2 film. The multilevel resistance states and the electric field controlled ferromagnetism have potential for applications in ultrahigh-density storage and magnetic logic device. PMID:26761365

  11. Self-selection effects and modulation of TaOx resistive switching random access memory with bottom electrode of highly doped Si

    NASA Astrophysics Data System (ADS)

    Yu, Muxi; Fang, Yichen; Wang, Zongwei; Pan, Yue; Li, Ming; Cai, Yimao; Huang, Ru

    2016-05-01

    In this paper, we propose a TaOx resistive switching random access memory (RRAM) device with operation-polarity-dependent self-selection effect by introducing highly doped silicon (Si) electrode, which is promising for large-scale integration. It is observed that with highly doped Si as the bottom electrode (BE), the RRAM devices show non-linear (>103) I-V characteristic during negative Forming/Set operation and linear behavior during positive Forming/Set operation. The underling mechanisms for the linear and non-linear behaviors at low resistance states of the proposed device are extensively investigated by varying operation modes, different metal electrodes, and Si doping type. Experimental data and theoretical analysis demonstrate that the operation-polarity-dependent self-selection effect in our devices originates from the Schottky barrier between the TaOx layer and the interfacial SiOx formed by reaction between highly doped Si BE and immigrated oxygen ions in the conductive filament area.

  12. Modulation of surface trap induced resistive switching by electrode annealing in individual PbS micro/nanowire-based devices for resistance random access memory.

    PubMed

    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. PMID:25398100

  13. SEU hardening of CMOS memory circuit

    NASA Technical Reports Server (NTRS)

    Whitaker, S.; Canaris, J.; Liu, K.

    1990-01-01

    This paper reports a design technique to harden CMOS memory circuits against Single Event Upset (SEU) in the space environment. A RAM cell and Flip Flop design are presented to demonstrate the method. The Flip Flop was used in the control circuitry for a Reed Solomon encoder designed for the Space Station.

  14. Efficient checkpointing schemes for depletion perturbation solutions on memory-limited architectures

    SciTech Connect

    Stripling, H. F.; Adams, M. L.; Hawkins, W. D.

    2013-07-01

    We describe a methodology for decreasing the memory footprint and machine I/O load associated with the need to access a forward solution during an adjoint solve. Specifically, we are interested in the depletion perturbation equations, where terms in the adjoint Bateman and transport equations depend on the forward flux solution. Checkpointing is the procedure of storing snapshots of the forward solution to disk and using these snapshots to recompute the parts of the forward solution that are necessary for the adjoint solve. For large problems, however, the storage cost of just a few copies of an angular flux vector can exceed the available RAM on the host machine. We propose a methodology that does not checkpoint the angular flux vector; instead, we write and store converged source moments, which are typically of a much lower dimension than the angular flux solution. This reduces the memory footprint and I/O load of the problem, but requires that we perform single sweeps to reconstruct flux vectors on demand. We argue that this trade-off is exactly the kind of algorithm that will scale on advanced, memory-limited architectures. We analyze the cost, in terms of FLOPS and memory footprint, of five checkpointing schemes. We also provide computational results that support the analysis and show that the memory-for-work trade off does improve time to solution. (authors)

  15. Performance improvement of the resistive memory properties of InGaZnO thin films by using microwave irradiation

    NASA Astrophysics Data System (ADS)

    Hwang, Yeong-Hyeon; An, Ho-Myoung; Cho, Won-Ju

    2014-01-01

    Microwave irradiation (MWI) at low temperature was employed in resistive random access memory (ReRAM) fabrication with InGaZnO (IGZO) thin-films as a switching medium, and the resistive switching behaviors were compared with conventional thermal annealing (CTA) process. A surface roughness of the MWI-treated IGZO layer is smoother than that of the CTA-treated layer. An electrical conduction mechanism of the MWI-treated device is similar to that of the pristine device, whereas the CTA device exhibits a different mechanism. After MWI treatment, the current ON/OFF ratio of IGZO ReRAMs significantly increased from 0.49 × 101 to 1.16 × 102, which was ascribed to the reduction in the OFF current. Further, the enlarged ON/OFF resistance window allowed sufficient data retention of >10 years at 85 °C. Owing to its smoother surface for stable resistive switching, low thermal budget, and process simplicity, MWI has great potential for metal-oxide ReRAMs in transparent and flexible system-on-panel applications.

  16. Fabrication of dynamic oxide semiconductor random access memory with 3.9 fF storage capacitance and greater than 1 h retention by using c-axis aligned crystalline oxide semiconductor transistor with L of 60 nm

    NASA Astrophysics Data System (ADS)

    Onuki, Tatsuya; Kato, Kiyoshi; Nomura, Masumi; Yakubo, Yuto; Nagatsuka, Shuhei; Matsuzaki, Takanori; Hondo, Suguru; Hata, Yuki; Okazaki, Yutaka; Nagai, Masaharu; Atsumi, Tomoaki; Sakakura, Masayuki; Okuda, Takashi; Yamamoto, Yoshitaka; Yamazaki, Shunpei

    2015-04-01

    A dynamic oxide semiconductor random access memory (DOSRAM) array that achieves reduction in storage capacitance (Cs) and decrease in refresh rate has been fabricated by using a c-axis aligned crystalline oxide semiconductor (CAAC-OS) transistor (L = 60 nm) with an extremely low off-state current. We have confirmed that this array, composed of cells that include a CAAC-OS transistor with W/L = 40 nm/60 nm using InGaZnO and a 3.9 fF storage capacitor, operates with write and read times of 5 ns. Therefore, DOSRAM can ensure sufficient Cs while maintaining operation speed comparable to that of dynamic random access memory (DRAM). We have found that the read signal voltage of DOSRAM is changed by approximately 30 mV after 1 h at 85 °C. Thus, DOSRAM is a promising replacement for DRAM.

  17. Modeling rammed earth wall using discrete element method

    NASA Astrophysics Data System (ADS)

    Bui, T.-T.; Bui, Q.-B.; Limam, A.; Morel, J.-C.

    2016-03-01

    Rammed earth is attracting renewed interest throughout the world thanks to its "green" characteristics in the context of sustainable development. Several research studies have thus recently been carried out to investigate this material. Some of them attempted to simulate the rammed earth's mechanical behavior by using analytical or numerical models. Most of these studies assumed that there was a perfect cohesion at the interface between earthen layers. This hypothesis proved to be acceptable for the case of vertical loading, but it could be questionable for horizontal loading. To address this problem, discrete element modeling seems to be relevant to simulate a rammed earth wall. To our knowledge, no research has been conducted thus far using discrete element modeling to study a rammed earth wall. This paper presents an assessment of the discrete element modeling's robustness for rammed earth walls. Firstly, a brief description of the discrete element modeling is presented. Then the parameters necessary for discrete element modeling of the material law of the earthen layers and their interfaces law following the Mohr-Coulomb model with a tension cut-off and post-peak softening were given. The relevance of the model and the material parameters were assessed by comparing them with experimental results from the literature. The results showed that, in the case of vertical loading, interfaces did not have an important effect. In the case of diagonal loading, model with interfaces produced better results. Interface characteristics can vary from 85 to 100% of the corresponding earthen layer's characteristics.

  18. Operational advances in ring current modeling using RAM-SCB

    SciTech Connect

    Welling, Daniel T; Jordanova, Vania K; Zaharia, Sorin G; Morley, Steven K

    2010-12-03

    The Ring current Atmosphere interaction Model with Self-Consistently calculated 3D Magnetic field (RAM-SCB) combines a kinetic model of the ring current with a force-balanced model of the magnetospheric magnetic field to create an inner magnetospheric model that is magnetically self consistent. RAM-SCB produces a wealth of outputs that are valuable to space weather applications. For example, the anisotropic particle distribution of the KeV-energy population calculated by the code is key for predicting surface charging on spacecraft. Furthermore, radiation belt codes stand to benefit substantially from RAM-SCB calculated magnetic field values and plasma wave growth rates - both important for determining the evolution of relativistic electron populations. RAM-SCB is undergoing development to bring these benefits to the space weather community. Data-model validation efforts are underway to assess the performance of the system. 'Virtual Satellite' capability has been added to yield satellite-specific particle distribution and magnetic field output. The code's outer boundary is being expanded to 10 Earth Radii to encompass previously neglected geosynchronous orbits and allow the code to be driven completely by either empirical or first-principles based inputs. These advances are culminating towards a new, real-time version of the code, rtRAM-SCB, that can monitor the inner magnetosphere conditions on both a global and spacecraft-specific level. This paper summarizes these new features as well as the benefits they provide the space weather community.

  19. Vehicle barrier with access delay

    DOEpatents

    Swahlan, David J; Wilke, Jason

    2013-09-03

    An access delay vehicle barrier for stopping unauthorized entry into secure areas by a vehicle ramming attack includes access delay features for preventing and/or delaying an adversary from defeating or compromising the barrier. A horizontally deployed barrier member can include an exterior steel casing, an interior steel reinforcing member and access delay members disposed within the casing and between the casing and the interior reinforcing member. Access delay members can include wooden structural lumber, concrete and/or polymeric members that in combination with the exterior casing and interior reinforcing member act cooperatively to impair an adversarial attach by thermal, mechanical and/or explosive tools.

  20. Wrap spring clutch syringe ram and frit mixer

    DOEpatents

    Simpson, Frank B.

    2006-07-25

    A wrap spring clutch syringe ram pushes at least one syringe with virtually instantaneous starting and stopping, and with constant motion at a defined velocity during the intervening push. The wrap spring clutch syringe ram includes an electric motor, a computer, a flywheel, a wrap spring clutch, a precision lead screw, a slide platform, and syringe reservoirs, a mixing chamber, and a reaction incubation tube. The electric motor drives a flywheel and the wrap spring clutch couples the precision lead screw to the flywheel when a computer enables a solenoid of the wrap spring clutch. The precision lead screw drives a precision slide which causes syringes to supply a portion of solution into the mixing chamber and the incubation tube. The wrap spring clutch syringe ram is designed to enable the quantitative study of solution phase chemical and biochemical reactions, particularly those reactions that occur on the subsecond time scale.

  1. Application of RAM to Facility/Laboratory Design

    SciTech Connect

    Mohammadi, K

    2008-04-14

    Reliability, Availability, and Maintainability (RAM) studies are extensively used for mission critical systems (e.g., weapons systems) to predict the RAM parameters at the preliminary design phase. A RAM methodology is presented for predicting facility/laboratory inherent availability (i.e., availability that only considers the steady-state effects of design) at the preliminary design phase in support of Department of Energy (DOE) Order 430.1A (Life Cycle Asset Management) and DOE Order 420.1B (Facility Safety). The methodology presented identifies the appropriate system-level reliability and maintainability metrics and discusses how these metrics are used in a fault tree analysis for predicting the facility/laboratory inherent availability. The inherent availability predicted is compared against design criteria to determine if changes to the facility/laboratory preliminary design are necessary to meet the required availability objective in the final design.

  2. Memory beyond expression.

    PubMed

    Delorenzi, A; Maza, F J; Suárez, L D; Barreiro, K; Molina, V A; Stehberg, J

    2014-01-01

    The idea that memories are not invariable after the consolidation process has led to new perspectives about several mnemonic processes. In this framework, we review our studies on the modulation of memory expression during reconsolidation. We propose that during both memory consolidation and reconsolidation, neuromodulators can determine the probability of the memory trace to guide behavior, i.e. they can either increase or decrease its behavioral expressibility without affecting the potential of persistent memories to be activated and become labile. Our hypothesis is based on the findings that positive modulation of memory expression during reconsolidation occurs even if memories are behaviorally unexpressed. This review discusses the original approach taken in the studies of the crab Neohelice (Chasmagnathus) granulata, which was then successfully applied to test the hypothesis in rodent fear memory. Data presented offers a new way of thinking about both weak trainings and experimental amnesia: memory retrieval can be dissociated from memory expression. Furthermore, the strategy presented here allowed us to show in human declarative memory that the periods in which long-term memory can be activated and become labile during reconsolidation exceeds the periods in which that memory is expressed, providing direct evidence that conscious access to memory is not needed for reconsolidation. Specific controls based on the constraints of reminders to trigger reconsolidation allow us to distinguish between obliterated and unexpressed but activated long-term memories after amnesic treatments, weak trainings and forgetting. In the hypothesis discussed, memory expressibility--the outcome of experience-dependent changes in the potential to behave--is considered as a flexible and modulable attribute of long-term memories. Expression seems to be just one of the possible fates of re-activated memories. PMID:25102126

  3. Influence of cooling rate in planar thermally assisted magnetic random access memory: Improved writeability due to spin-transfer-torque influence

    SciTech Connect

    Chavent, A.; Ducruet, C.; Portemont, C.; Creuzet, C.; Alvarez-Hérault, J.; Vila, L.; Sousa, R. C.; Prejbeanu, I. L.; Dieny, B.

    2015-09-14

    This paper investigates the effect of a controlled cooling rate on magnetic field reversal assisted by spin transfer torque (STT) in thermally assisted magnetic random access memory. By using a gradual linear decrease of the voltage at the end of the write pulse, the STT decays more slowly or at least at the same rate as the temperature. This condition is necessary to make sure that the storage layer magnetization remains in the desired written direction during cooling of the cell. The influence of the write current pulse decay rate was investigated on two exchange biased synthetic ferrimagnet (SyF) electrodes. For a NiFe based electrode, a significant improvement in writing reproducibility was observed using a gradual linear voltage transition. The write error rate decreases by a factor of 10 when increasing the write pulse fall-time from ∼3 ns to 70 ns. For comparison, a second CoFe/NiFe based electrode was also reversed by magnetic field assisted by STT. In this case, no difference between sharp and linear write pulse fall shape was observed. We attribute this observation to the higher thermal stability of the CoFe/NiFe electrode during cooling. In real-time measurements of the magnetization reversal, it was found that Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling in the SyF electrode vanishes for the highest pulse voltages that were used due to the high temperature reached during write. As a result, during the cooling phase, the final state is reached through a spin-flop transition of the SyF storage layer.

  4. Influence of cooling rate in planar thermally assisted magnetic random access memory: Improved writeability due to spin-transfer-torque influence

    NASA Astrophysics Data System (ADS)

    Chavent, A.; Ducruet, C.; Portemont, C.; Creuzet, C.; Vila, L.; Alvarez-Hérault, J.; Sousa, R. C.; Prejbeanu, I. L.; Dieny, B.

    2015-09-01

    This paper investigates the effect of a controlled cooling rate on magnetic field reversal assisted by spin transfer torque (STT) in thermally assisted magnetic random access memory. By using a gradual linear decrease of the voltage at the end of the write pulse, the STT decays more slowly or at least at the same rate as the temperature. This condition is necessary to make sure that the storage layer magnetization remains in the desired written direction during cooling of the cell. The influence of the write current pulse decay rate was investigated on two exchange biased synthetic ferrimagnet (SyF) electrodes. For a NiFe based electrode, a significant improvement in writing reproducibility was observed using a gradual linear voltage transition. The write error rate decreases by a factor of 10 when increasing the write pulse fall-time from ˜3 ns to 70 ns. For comparison, a second CoFe/NiFe based electrode was also reversed by magnetic field assisted by STT. In this case, no difference between sharp and linear write pulse fall shape was observed. We attribute this observation to the higher thermal stability of the CoFe/NiFe electrode during cooling. In real-time measurements of the magnetization reversal, it was found that Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling in the SyF electrode vanishes for the highest pulse voltages that were used due to the high temperature reached during write. As a result, during the cooling phase, the final state is reached through a spin-flop transition of the SyF storage layer.

  5. Optical mass memories

    NASA Technical Reports Server (NTRS)

    Bailey, G. A.

    1976-01-01

    Optical and magnetic variants in the design of trillion-bit read/write memories are compared and tabulated. Components and materials suitable for a random access read/write nonmoving memory system are examined, with preference given to holography and photoplastic materials. Advantages and deficiencies of photoplastics are reviewed. Holographic page composer design, essential features of an optical memory with no moving parts, fiche-oriented random access memory design, and materials suitable for an efficient photoplastic fiche are considered. The optical variants offer advantages in lower volume and weight at data transfer rates near 1 Mbit/sec, but power drain is of the same order as for the magnetic variants (tape memory, disk memory). The mechanical properties of photoplastic film materials still leave much to be desired.

  6. Improved Writing-Conductor Designs For Magnetic Memory

    NASA Technical Reports Server (NTRS)

    Wu, Jiin-Chuan; Stadler, Henry L.; Katti, Romney R.

    1994-01-01

    Writing currents reduced to practical levels. Improved conceptual designs for writing conductors in micromagnet/Hall-effect random-access integrated-circuit memory reduces electrical current needed to magnetize micromagnet in each memory cell. Basic concept of micromagnet/Hall-effect random-access memory presented in "Magnetic Analog Random-Access Memory" (NPO-17999).

  7. In-flight and ground testing of single event upset sensitivity in static RAMs

    SciTech Connect

    Johansson, K.; Dyreklev, P.; Granbom, B.; Calvet, C.; Fourtine, S.; Feuillatre, O.

    1998-06-01

    This paper presents the results from in-flight measurements of single event upsets (SEU) in static random access memories (SRAM) caused by the atmospheric radiation environment at aircraft altitudes. The memory devices were carried on commercial airlines at high altitude and mainly high latitudes. The SEUs were monitored by a Component Upset Test Equipment (CUTE), designed for this experiment. The in flight results are compared to ground based testing with neutrons from three different sources.

  8. Simulation of the flow field of a ram accelerator

    NASA Astrophysics Data System (ADS)

    Soetrisno, Moeljo; Imlay, Scott T.

    1991-06-01

    An effort is made to achieve a more complete numerical model than heretofore available for analysis and performance prediction regarding ram-accelerator projectiles, using the finite-rate chemistry code HANA. Results are presented from such analyses of a ram accelerator projectile operating in both the thermally-choked mode and the transdetonative mode. The flow field about the projectile, the complex oblique shock system, and the flow properties in the combusting region are detailed. The code uses a novel diagonal implicit solution algorithm which eliminates the expense of inverting the large block matrices arising in chemically reacting flows.

  9. Data requirements for verification of ram glow chemistry

    NASA Technical Reports Server (NTRS)

    Swenson, G. R.; Mende, S. B.

    1985-01-01

    A set of questions is posed regarding the surface chemistry producing the ram glow on the space shuttle. The questions surround verification of the chemical cycle involved in the physical processes leading to the glow. The questions, and a matrix of measurements required for most answers, are presented. The measurements include knowledge of the flux composition to and from a ram surface as well as spectroscopic signatures from the U to visible to IR. A pallet set of experiments proposed to accomplish the measurements is discussed. An interim experiment involving an available infrared instrument to be operated from the shuttle Orbiter cabin is also be discussed.

  10. Formation polarity dependent improved resistive switching memory characteristics using nanoscale (1.3 nm) core-shell IrOx nano-dots

    PubMed Central

    2012-01-01

    Improved resistive switching memory characteristics by controlling the formation polarity in an IrOx/Al2O3/IrOx-ND/Al2O3/WOx/W structure have been investigated. High density of 1 × 1013/cm2 and small size of 1.3 nm in diameter of the IrOx nano-dots (NDs) have been observed by high-resolution transmission electron microscopy. The IrOx-NDs, Al2O3, and WOx layers are confirmed by X-ray photo-electron spectroscopy. Capacitance-voltage hysteresis characteristics show higher charge-trapping density in the IrOx-ND memory as compared to the pure Al2O3 devices. This suggests that the IrOx-ND device has more defect sites than that of the pure Al2O3 devices. Stable resistive switching characteristics under positive formation polarity on the IrOx electrode are observed, and the conducting filament is controlled by oxygen ion migration toward the Al2O3/IrOx top electrode interface. The switching mechanism is explained schematically based on our resistive switching parameters. The resistive switching random access memory (ReRAM) devices under positive formation polarity have an applicable resistance ratio of > 10 after extrapolation of 10 years data retention at 85°C and a long read endurance of 105 cycles. A large memory size of > 60 Tbit/sq in. can be realized in future for ReRAM device application. This study is not only important for improving the resistive switching memory performance but also help design other nanoscale high-density nonvolatile memory in future. PMID:22439604

  11. Involvement of Regulatory Interactions among Global Regulators GlxR, SugR, and RamA in Expression of ramA in Corynebacterium glutamicum

    PubMed Central

    Toyoda, Koichi; Teramoto, Haruhiko; Gunji, Wataru; Inui, Masayuki

    2013-01-01

    The central carbon metabolism genes in Corynebacterium glutamicum are under the control of a transcriptional regulatory network composed of several global regulators. It is known that the promoter region of ramA, encoding one of these regulators, interacts with its gene product, RamA, as well as with the two other regulators, GlxR and SugR, in vitro and/or in vivo. Although RamA has been confirmed to repress its own expression, the roles of GlxR and SugR in ramA expression have remained unclear. In this study, we examined the effects of GlxR binding site inactivation on expression of the ramA promoter-lacZ fusion in the genetic background of single and double deletion mutants of sugR and ramA. In the wild-type background, the ramA promoter activity was reduced to undetectable levels by the introduction of mutations into the GlxR binding site but increased by sugR deletion, indicating that GlxR and SugR function as the transcriptional activator and repressor, respectively. The marked repression of ramA promoter activity by the GlxR binding site mutations was largely compensated for by deletions of sugR and/or ramA. Furthermore, ramA promoter activity in the ramA-sugR double mutant was comparable to that in the ramA mutant but was significantly higher than that in the sugR mutant. Taken together, it is likely that the level of ramA expression is dynamically balanced by GlxR-dependent activation and repression by RamA along with SugR in response to perturbation of extracellular and/or intracellular conditions. These findings add multiple regulatory loops to the transcriptional regulatory network model in C. glutamicum. PMID:23396909

  12. Quantum memory Quantum memory

    NASA Astrophysics Data System (ADS)

    Le Gouët, Jean-Louis; Moiseev, Sergey

    2012-06-01

    Interaction of quantum radiation with multi-particle ensembles has sparked off intense research efforts during the past decade. Emblematic of this field is the quantum memory scheme, where a quantum state of light is mapped onto an ensemble of atoms and then recovered in its original shape. While opening new access to the basics of light-atom interaction, quantum memory also appears as a key element for information processing applications, such as linear optics quantum computation and long-distance quantum communication via quantum repeaters. Not surprisingly, it is far from trivial to practically recover a stored quantum state of light and, although impressive progress has already been accomplished, researchers are still struggling to reach this ambitious objective. This special issue provides an account of the state-of-the-art in a fast-moving research area that makes physicists, engineers and chemists work together at the forefront of their discipline, involving quantum fields and atoms in different media, magnetic resonance techniques and material science. Various strategies have been considered to store and retrieve quantum light. The explored designs belong to three main—while still overlapping—classes. In architectures derived from photon echo, information is mapped over the spectral components of inhomogeneously broadened absorption bands, such as those encountered in rare earth ion doped crystals and atomic gases in external gradient magnetic field. Protocols based on electromagnetic induced transparency also rely on resonant excitation and are ideally suited to the homogeneous absorption lines offered by laser cooled atomic clouds or ion Coulomb crystals. Finally off-resonance approaches are illustrated by Faraday and Raman processes. Coupling with an optical cavity may enhance the storage process, even for negligibly small atom number. Multiple scattering is also proposed as a way to enlarge the quantum interaction distance of light with matter. The

  13. Working memory capacity and controlled serial memory search.

    PubMed

    Mızrak, Eda; Öztekin, Ilke

    2016-08-01

    The speed-accuracy trade-off (SAT) procedure was used to investigate the relationship between working memory capacity (WMC) and the dynamics of temporal order memory retrieval. High- and low-span participants (HSs, LSs) studied sequentially presented five-item lists, followed by two probes from the study list. Participants indicated the more recent probe. Overall, accuracy was higher for HSs compared to LSs. Crucially, in contrast to previous investigations that observed no impact of WMC on speed of access to item information in memory (e.g., Öztekin & McElree, 2010), recovery of temporal order memory was slower for LSs. While accessing an item's representation in memory can be direct, recovery of relational information such as temporal order information requires a more controlled serial memory search. Collectively, these data indicate that WMC effects are particularly prominent during high demands of cognitive control, such as serial search operations necessary to access temporal order information from memory. PMID:27135712

  14. Treating ram sperm with cholesterol-loaded cyclodextrins improves cryosurvival

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diluted ram sperm can be held for 24 h at 5º C prior to cryopreservation without impacting cryosurvival rates, however, the effects this storage has on subsequent fertility is unknown. These studies were conducted to evaluate the fertility of semen held for 24 h (to mimic shipping semen to a cryopr...

  15. Initiation of combustion in the thermally choked ram accelerator

    NASA Astrophysics Data System (ADS)

    Bruckner, A. P.; Burnham, E. A.; Knowlen, C.; Hertzberg, A.; Bogdanoff, D. W.

    The methodology for initiating stable combustion in a ram accelerator operating in the thermally choked mode is presented in this paper. The ram accelerator is a high velocity ramjet-in-tube projectile launcher whose principle of operation is similar to that of an airbreathing ramjet. The subcaliber projectile travels supersonically through a stationary tube filled with a premixed combustible gas mixture. In the thermally choked propulsion mode subsonic combustion takes place behind the base of the projectile and leads to thermal choking, which stabilizes a normal shock system on the projectile, thus producing forward thrust. Projectiles with masses in the 45-90 g range have been accelerated to velocities up to 2650 m/sec in a 38 mm bore, 16 m long accelerator tube. Operation of the ram accelerator is started by injecting the projectile into the accelerator tube at velocities in the 700 - 1300 m/sec range by means of a conventional gas gun. A specially designed obturator, which seals the bore of the gun during this initial acceleration, enters the ram accelerator together with the projectile. The interaction of the obturator with the propellant gas ignites the gas mixture and establishes stable combustion behind the projectile.

  16. The Neurobiology of Sexual Partner Preferences in Rams

    PubMed Central

    Roselli, Charles E.; Stormshak, Fred

    2009-01-01

    The question of what causes a male animal to seek out and choose a female as opposed to another male mating partner is unresolved and remains an issue of considerable debate. The most developed biologic theory is the perinatal organizational hypothesis, which states that perinatal hormone exposure mediates sexual differentiation of the brain. Numerous animal experiments have assessed the contribution of perinatal testosterone and/or estradiol exposure to the development of a male-typical mate preference, but almost all have used hormonally manipulated animals. In contrast, variations in sexual partner preferences occur spontaneously in domestic rams, with as many as 8% of the population exhibiting a preference for same-sex mating partners (male-oriented rams). Thus, the domestic ram is an excellent experimental model to study possible links between fetal neuroendocrine programming of neural mechanisms and adult sexual partner preferences. In this review, we present an overview of sexual differentiation in relation to sexual partner preferences. We then summarize results that test the relevance of the organizational hypothesis to expression of same-sex sexual partner preferences in rams. Finally, we demonstrate that the sexual differentiation of brain and behavior in sheep do not depend critically on aromatization of testosterone to estradiol. PMID:19446078

  17. Does breed of ram affect ewe and lamb productivity?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Systematic use of breed diversity in terminal crossbreeding systems can improve the efficiency of commercial lamb production. Data from controlled research should be used to select the genetic line or lines of rams to use in terminal crossbreeding systems. Thus, research is underway at the USDA, ARS...

  18. BioRAM Lite v.1.0

    2010-08-05

    BioRAM lite is a training tool for teaching the processes which should be using in assessing biosafety and biosecurity risks. The tool includes 4 separate workbooks – two for biosafety and two for biosecurity. The tools include a set of questions which are scored using ordinal values and the mathematical equations to combine the answers into likelihood and consequence values.

  19. Ram pressure stripping in elliptical galaxies - II. Magnetic field effects

    NASA Astrophysics Data System (ADS)

    Shin, Min-Su; Ruszkowski, Mateusz

    2014-12-01

    We investigate the effects of magnetic fields and turbulence on ram pressure stripping in elliptical galaxies using ideal magnetohydrodynamic simulations. We consider weakly magnetized interstellar medium (ISM) characterized by subsonic turbulence, and two orientations of the magnetic fields in the intracluster medium (ICM) - parallel and perpendicular to the direction of the galaxy motion through the ICM. While the stronger turbulence enhances the ram pressure stripping mass-loss, the magnetic fields tend to suppress the stripping rates, and the suppression is stronger for parallel fields. However, the effect of magnetic fields on the mass stripping rate is mild. Nevertheless, the morphology of the stripping tails depends significantly on the direction of the ICM magnetic field. The effect of the magnetic field geometry on the tail morphology is much stronger than that of the level of the ISM turbulence. The tail has a highly collimated shape for parallel fields, while it has a sheet-like morphology in the plane of the ICM magnetic field for perpendicular fields. The magnetic field in the tail is amplified irrespectively of the orientation of the ICM field. More strongly magnetized regions in the ram pressure stripping tails are expected to have systematically higher metallicity due to the strong concentration of the stripped ISM than the less magnetized regions. Strong dependence of the morphology of the stripped ISM on the magnetic field could potentially be used to constrain the relative orientation of the ram pressure direction and the dominant component of the ICM magnetic field.

  20. Copper toxicity in confinement-housed ram lambs.

    PubMed Central

    Lewis, N J; Fallah-Rad, A H; Connor, M L

    1997-01-01

    Fourteen Suffolk rams (6 mo) were diagnosed with chronic copper poisoning. Preliminary results indicated that a combination of serum aspartate aminotransferase, gamma glutamyltransferase, and copper could be used as a test so that high risk lambs could be treated more aggressively. PMID:9262859

  1. USER'S GUIDE FOR RAM. VOLUME II. DATA PREPARATION AND LISTINGS

    EPA Science Inventory

    The information presented in this user's guide is directed to air pollution scientists having an interest in applying air quality simulation models. RAM is a method of estimating short-term dispersion using the Gaussian steady-state model. These algorithms can be used for estimat...

  2. USER'S GUIDE FOR RAM. VOLUME I. ALGORITHM DESCRIPTION AND USE

    EPA Science Inventory

    The information presented in this user's guide is directed to air pollution scientists having an interest in applying air quality simulation models. RAM is a method of estimating short-term dispersion using the Gaussian steady-state model. These algorithms can be used for estimat...

  3. An evaluation of RAMS radiation schemes by field measurements

    SciTech Connect

    Zhong, S; Doran, J C

    1994-02-01

    At present, two radiation schemes are used in RAMS: the Mahrer and Pielke (M-P) scheme and the Chen and Cotton (C-C) scheme. The M-P scheme requires little computational expense, but does not include the radiative effects of liquid water or ice; the C-C scheme accounts for the radiative effects of liquid water and ice but is fairly expensive computationally. For simulations with clouds, the C-C scheme is obviously a better choice, but for clear sky conditions, RAMS users face a decision regarding which radiation scheme to use. It has been noted that the choice of radiation scheme may result in significantly different results for the same case. To examine the differences in the radiative fluxes and the boundary-layer structure corresponding to the two radiation schemes in RAMS we have carried out a study where Rams was used to simulate the same case with two different radiation schemes. The modeled radiative fluxes by the two schemes were then compared with the field measurements. A description of the observations and the case study, a comparison and discussion of the results, and a summary and conclusions follow.

  4. Experimental studies on methane-fuel laboratory scale ram combustor

    SciTech Connect

    Kinoshita, Y.; Kitajima, J.; Seki, Y.; Tatara, A.

    1995-07-01

    The laboratory scale ram combustor test program has been investigating fundamental combustion characteristics of a ram combustor, which operates from Mach 2.5 to 5 for the super/hypersonic transport propulsion system. In the previous study, combustion efficiency had been found poor, less than 70 percent, due to a low inlet air temperature and a high velocity at Mach 3 condition. To improve the low combustion efficiency, a fuel zoning combustion concept was investigated by using a subscale combustor model first. Combustion efficiency more than 90 percent was achieved and the concept was found very effective. Then a laboratory scale ram combustor was fabricated and combustion tests were carried out mainly at the simulated condition of Mach 5. A vitiation technique wa used to simulate a high temperature of 1,263 K. The test results indicate that ignition, flame stability, and combustion efficiency were not significant, but the NO{sub x} emissions are a critical problem for the ram combustor at Mach 5 condition.

  5. 17. Detail of base of 'Flying Ram' in NW corner ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. Detail of base of 'Flying Ram' in NW corner of foyer. Camera is looking SW. First doorway beyond fountain leads to basement and men's lounge seen in WA-197-44. Second doorway leads to storefront corner at Seventh Ave. and Olive Way. (Aug. 1991) - Fox Theater, Seventh Avenue & Olive Way, Seattle, King County, WA

  6. Initiation of combustion in the thermally choked ram accelerator

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Burnham, E. A.; Knowlen, C.; Hertzberg, A.; Bogdanoff, D. W.

    1992-01-01

    The methodology for initiating stable combustion in a ram accelerator operating in the thermally choked mode is presented in this paper. The ram accelerator is a high velocity ramjet-in-tube projectile launcher whose principle of operation is similar to that of an airbreathing ramjet. The subcaliber projectile travels supersonically through a stationary tube filled with a premixed combustible gas mixture. In the thermally choked propulsion mode subsonic combustion takes place behind the base of the projectile and leads to thermal choking, which stabilizes a normal shock system on the projectile, thus producing forward thrust. Projectiles with masses in the 45-90 g range have been accelerated to velocities up to 2650 m/sec in a 38 mm bore, 16 m long accelerator tube. Operation of the ram accelerator is started by injecting the projectile into the accelerator tube at velocities in the 700 - 1300 m/sec range by means of a conventional gas gun. A specially designed obturator, which seals the bore of the gun during this initial acceleration, enters the ram accelerator together with the projectile. The interaction of the obturator with the propellant gas ignites the gas mixture and establishes stable combustion behind the projectile.

  7. Experimental demonstration of a 120-mm ram accelerator

    NASA Astrophysics Data System (ADS)

    Kruczynski, David L.

    1992-10-01

    Ram acceleration is an emerging propulsion technology in which a projectile similar in shape to the centerbody of a ramjet aircraft engine is injected at high speed into a tube filled with a combustible gaseous mixture. As the projectile moves into the tube, under supersonic conditions, shocks occur on and around the projectile. If the gases are then ignited either by the energy in the shock system or an external mechanism, the combustion around or behind the projectile can be self-sustaining. The net effect is to generate a localized high pressure region around and/or behind the projectile which produces acceleration. Work at the University of Washington, Seattle, has demonstrated velocities in excess of 2.6 km/s in 38-mm caliber, while theory predicts velocities above 7 km/s may be obtainable. A program was initiated at the Weapons Technology Directorate of the US Army Research Laboratory (formerly Ballistic Research Laboratory) to examine the scaling potential of ram acceleration for use as a high velocity, high mass, (i.e., high kinetic energy) launcher. Data from initial gas mixing tests and first firings through a 120-mm bore diameter ram accelerator with both inert and live fuel gases are presented. Initial comparisons with ram accelerators of smaller scale are made. Discussions of scaling parameters as currently understood will be presented.

  8. Architecture of the sperm whale forehead facilitates ramming combat

    PubMed Central

    Spyridis, Panagiotis; Mehari Abraha, Hyab; Carrier, David R.; Pataky, Todd C.

    2016-01-01

    Herman Melville’s novel Moby Dick was inspired by historical instances in which large sperm whales (Physeter macrocephalus L.) sank 19th century whaling ships by ramming them with their foreheads. The immense forehead of sperm whales is possibly the largest, and one of the strangest, anatomical structures in the animal kingdom. It contains two large oil-filled compartments, known as the “spermaceti organ” and “junk,” that constitute up to one-quarter of body mass and extend one-third of the total length of the whale. Recognized as playing an important role in echolocation, previous studies have also attributed the complex structural configuration of the spermaceti organ and junk to acoustic sexual selection, acoustic prey debilitation, buoyancy control, and aggressive ramming. Of these additional suggested functions, ramming remains the most controversial, and the potential mechanical roles of the structural components of the spermaceti organ and junk in ramming remain untested. Here we explore the aggressive ramming hypothesis using a novel combination of structural engineering principles and probabilistic simulation to determine if the unique structure of the junk significantly reduces stress in the skull during quasi-static impact. Our analyses indicate that the connective tissue partitions in the junk reduce von Mises stresses across the skull and that the load-redistribution functionality of the former is insensitive to moderate variation in tissue material parameters, the thickness of the partitions, and variations in the location and angle of the applied load. Absence of the connective tissue partitions increases skull stresses, particularly in the rostral aspect of the upper jaw, further hinting of the important role the architecture of the junk may play in ramming events. Our study also found that impact loads on the spermaceti organ generate lower skull stresses than an impact on the junk. Nevertheless, whilst an impact on the spermaceti organ

  9. Architecture of the sperm whale forehead facilitates ramming combat.

    PubMed

    Panagiotopoulou, Olga; Spyridis, Panagiotis; Mehari Abraha, Hyab; Carrier, David R; Pataky, Todd C

    2016-01-01

    Herman Melville's novel Moby Dick was inspired by historical instances in which large sperm whales (Physeter macrocephalus L.) sank 19th century whaling ships by ramming them with their foreheads. The immense forehead of sperm whales is possibly the largest, and one of the strangest, anatomical structures in the animal kingdom. It contains two large oil-filled compartments, known as the "spermaceti organ" and "junk," that constitute up to one-quarter of body mass and extend one-third of the total length of the whale. Recognized as playing an important role in echolocation, previous studies have also attributed the complex structural configuration of the spermaceti organ and junk to acoustic sexual selection, acoustic prey debilitation, buoyancy control, and aggressive ramming. Of these additional suggested functions, ramming remains the most controversial, and the potential mechanical roles of the structural components of the spermaceti organ and junk in ramming remain untested. Here we explore the aggressive ramming hypothesis using a novel combination of structural engineering principles and probabilistic simulation to determine if the unique structure of the junk significantly reduces stress in the skull during quasi-static impact. Our analyses indicate that the connective tissue partitions in the junk reduce von Mises stresses across the skull and that the load-redistribution functionality of the former is insensitive to moderate variation in tissue material parameters, the thickness of the partitions, and variations in the location and angle of the applied load. Absence of the connective tissue partitions increases skull stresses, particularly in the rostral aspect of the upper jaw, further hinting of the important role the architecture of the junk may play in ramming events. Our study also found that impact loads on the spermaceti organ generate lower skull stresses than an impact on the junk. Nevertheless, whilst an impact on the spermaceti organ would

  10. Nonvolatile Memory Technology for Space Applications

    NASA Technical Reports Server (NTRS)

    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.

  11. Forging of compressor blades: Temperature and ram velocity effects

    SciTech Connect

    Saigal, A.; Zhen, K.; Chan, T.S.

    1995-07-01

    Forging is one of the most widely used manufacturing process for making high-strength, structurally integrated, impact and creep-resistant Ti-6Al-4V compressor blades for jet engines. In addition, in modern metal forming technology, finite element analysis method and computer modeling are being extensively employed for initial evaluation and optimization of various processes, including forging. In this study, DEFORM, a rigid viscoplastic two-dimensional finite element code was used to study the effects of initial die temperature and initial ram velocity on the forging process. For a given billet, die temperature and ram velocity influence the strain rate, temperature distribution,and thus the flow stress of the material. The die temperature and the ram velocity were varied over the range 300 to 700 F and 15--25 in./sec, respectively, to estimate the maximum forging load and the total energy required to forge compressor blades. The ram velocity was assumed to vary linearly as a function of stroke. Based on the analysis,it was found the increasing the die temperature from 300 to 700 F decreases the forging loads by 19.9 percent and increases the average temperature of the workpiece by 43 F. Similarly, increasing the initial ram velocity from 15 to 25 in./sec decreases the forging loads by 25.2 percent and increases the average temperature of the workpiece by 36 F. The nodal temperature distribution is bimodal in each case. The forging energy required to forge the blades is approximately 18 kips *in./in.

  12. Evidence of melatonin synthesis in the ram reproductive tract.

    PubMed

    Gonzalez-Arto, M; Hamilton, T R Dos S; Gallego, M; Gaspar-Torrubia, E; Aguilar, D; Serrano-Blesa, E; Abecia, J A; Pérez-Pé, R; Muiño-Blanco, T; Cebrián-Pérez, J A; Casao, A

    2016-01-01

    Melatonin is a ubiquitous molecule found in a wide range of fluids, one of them being ram seminal plasma, in which it can reach higher concentrations than those found in blood, suggesting an extrapineal secretion by the reproductive tract. In order to identify the source of the melatonin found in ram seminal plasma, we first tried to determine whether the melatonin levels were maintained during the day. For this purpose, melatonin concentrations were measured in seminal plasma obtained from first ejaculates of six rams at 6:00 a.m. in total darkness, at 10:00 a.m. and at 14:00 p.m. The melatonin concentration was higher (p < 0.05) in ejaculates collected at 6:00 a.m. than at 10:00 and 14:00. There was no statistical difference between the latter. To further corroborate an extrapineal secretion of melatonin, the presence of the two key enzymes involved in melatonin synthesis, arylalkylamine-N-acetyltransferase (AANAT) and N-acetylserotonin-O-methyltransferase (ASMT) was analyzed by RT-PCR, q-PCR and Western-blot in ram testes, epididymis, and accessory glands. The RT-PCR showed the presence of the m-RNA codifying both AANAT and ASTM in all the tissues under study, but the q-PCR and Western-blot revealed that gene expression of these enzymes was significantly higher in the testis (p < 0.05). Immunohistochemistry confirmed the presence of AANAT and ASMT in the testis and revealed that they were found in the Leydig cells, spermatocytes, and spermatids. Also, measurable levels of melatonin were found in testicular tissue and the tail of the epididymis. In conclusion, our study indicates that the testes are one of the likely sources of the high levels of melatonin found in ram seminal plasma, at least during the day. PMID:26742835

  13. RAM: a Relativistic Adaptive Mesh Refinement Hydrodynamics Code

    SciTech Connect

    Zhang, Wei-Qun; MacFadyen, Andrew I.; /Princeton, Inst. Advanced Study

    2005-06-06

    The authors have developed a new computer code, RAM, to solve the conservative equations of special relativistic hydrodynamics (SRHD) using adaptive mesh refinement (AMR) on parallel computers. They have implemented a characteristic-wise, finite difference, weighted essentially non-oscillatory (WENO) scheme using the full characteristic decomposition of the SRHD equations to achieve fifth-order accuracy in space. For time integration they use the method of lines with a third-order total variation diminishing (TVD) Runge-Kutta scheme. They have also implemented fourth and fifth order Runge-Kutta time integration schemes for comparison. The implementation of AMR and parallelization is based on the FLASH code. RAM is modular and includes the capability to easily swap hydrodynamics solvers, reconstruction methods and physics modules. In addition to WENO they have implemented a finite volume module with the piecewise parabolic method (PPM) for reconstruction and the modified Marquina approximate Riemann solver to work with TVD Runge-Kutta time integration. They examine the difficulty of accurately simulating shear flows in numerical relativistic hydrodynamics codes. They show that under-resolved simulations of simple test problems with transverse velocity components produce incorrect results and demonstrate the ability of RAM to correctly solve these problems. RAM has been tested in one, two and three dimensions and in Cartesian, cylindrical and spherical coordinates. they have demonstrated fifth-order accuracy for WENO in one and two dimensions and performed detailed comparison with other schemes for which they show significantly lower convergence rates. Extensive testing is presented demonstrating the ability of RAM to address challenging open questions in relativistic astrophysics.

  14. Penicillamine prevents ram sperm agglutination in media that support capacitation.

    PubMed

    Leahy, T; Rickard, J P; Aitken, R J; de Graaf, S P

    2016-02-01

    Ram spermatozoa are difficult to capacitate in vitro. Here we describe a further complication, the unreported phenomenon of head-to-head agglutination of ram spermatozoa following dilution in the capacitation medium Tyrodes plus albumin, lactate and pyruvate (TALP). Sperm agglutination is immediate, specific and persistent and is not associated with a loss of motility. Agglutination impedes in vitro sperm handling and analysis. So the objectives of this study were to investigate the cause of sperm agglutination and potential agents which may reduce agglutination. The percentage of non-agglutinated, motile spermatozoa increased when bicarbonate was omitted from complete TALP suggesting that bicarbonate ions stimulate the agglutination process. d-penicillamine (PEN), a nucleophilic thiol, was highly effective at reducing agglutination. The inclusion of 250 μM PEN in TALP reduced the incidence of motile, agglutinated spermatozoa from 76.7 ± 2.7% to 2.8 ± 1.4%. It was then assessed if PEN (1 mM) could be included in existing ram sperm capacitation protocols (TALP +1 mM dibutyryl cAMP, caffeine and theophylline) to produce spermatozoa that were simultaneously capacitated and non-agglutinated. This protocol resulted in a sperm population which displayed high levels of tyrosine phosphorylated proteins and lipid disordered membranes (merocyanine-540) while remaining motile, viable, acrosome-intact and non-agglutinated. In summary, PEN (1 mM) can be included in ram sperm capacitation protocols to reduce sperm agglutination and allow for the in vitro assessment of ram sperm capacitation. PMID:26705263

  15. Single event upset vulnerability of selected 4K and 16K CMOS static RAM's

    NASA Technical Reports Server (NTRS)

    Kolasinski, W. A.; Koga, R.; Blake, J. B.; Brucker, G.; Pandya, P.; Petersen, E.; Price, W.

    1982-01-01

    Upset thresholds for bulk CMOS and CMOS/SOS RAMS were deduced after bombardment of the devices with 140 MeV Kr, 160 MeV Ar, and 33 MeV O beams in a cyclotron. The trials were performed to test prototype devices intended for space applications, to relate feature size to the critical upset charge, and to check the validity of computer simulation models. The tests were run on 4 and 1 K memory cells with 6 transistors, in either hardened or unhardened configurations. The upset cross sections were calculated to determine the critical charge for upset from the soft errors observed in the irradiated cells. Computer simulations of the critical charge were found to deviate from the experimentally observed variation of the critical charge as the square of the feature size. Modeled values of series resistors decoupling the inverter pairs of memory cells showed that above some minimum resistance value a small increase in resistance produces a large increase in the critical charge, which the experimental data showed to be of questionable validity unless the value is made dependent on the maximum allowed read-write time.

  16. Memory for Traumatic Experiences in Early Childhood

    ERIC Educational Resources Information Center

    Cordon, Ingrid M.; Pipe, Margaret-Ellen; Sayfan, Liat; Melinder, Annika; Goodman, Gail S.

    2004-01-01

    Traumatic experiences in early childhood raise important questions about memory development in general and about the durability and accessibility of memories for traumatic events in particular. We discuss memory for early childhood traumatic events, from a developmental perspective, focusing on those factors that may equally influence memories for…

  17. Autosuggestibility in memory development.

    PubMed

    Brainerd, C J; Reyna, V F

    1995-02-01

    Autosuggestibility is a potentially common source of false memories in children. We studied a form of autosuggestibility in which children's answers to memory tests were shifted in the direction of their illogical solutions to reasoning problems. In Experiments 1 and 2, illogic-consistent shifts were identified in children's memories of the numerical inputs on class-inclusion problems. The magnitudes of the shifts declined with age, and they appeared to be due to the intrusion of inappropriate gist on memory probes rather than retroactive interference from illogical reasoning. A model of how gist intrusion causes autosuggestibility was investigated in Experiments 3-5. The model assumes that children retrieve and process inappropriate gist when memory tests supply cues that are inadequate to permit access to verbatim memories. PMID:7895469

  18. Does fascia hold memories?

    PubMed

    Tozzi, Paolo

    2014-04-01

    The idea that tissues may possess some sort of memory is a controversial topic in manual medicine, calling for research and clinical exploration. Many bodyworkers, at some point in their practice, have experienced phenomena that may be interpreted as representing a release of memory traces when working on dysfunctional tissues. This feeling may have been accompanied by some type of sensory experience, for the therapist and/or the patient. In some cases, early traumatic experiences may be recalled. When this happens, the potency of the memory may be erased or eased, along with restoration of tissue function. Hence the questions: can memories be held in the fascia? And: are these memories accessible during manual fascial work? Modern research has proposed a variety of different interpretations as to how memory might be stored in soft tissues, possibly involving other forms of information storage not exclusively processed neurologically (Box 1). PMID:24725795

  19. Investigation of starting transients in the thermally choked ram accelerator

    NASA Astrophysics Data System (ADS)

    Burnham, E. A.; Hinkey, J. B.; Bruckner, A. P.

    1992-10-01

    An experimental investigation of the starting transients of the thermally choked ram accelerator is presented in this paper. Construction of a highly instrumented tube section and instrumentation inserts provide high resolution experimental pressure, luminosity, and electromagnetic data of the starting transients. Data obtained prior to and following the entrance diaphragm show detailed development of shock systems in both combustible and inert mixtures. With an evacuated launch tube, starting the diffuser is possible at any Mach number above the Kantrowitz Mach number. The detrimental effects and possible solutions of higher launch tube pressures and excessive obturator leakage (blow-by) are discussed. Ignition of a combustible mixture is demonstrated with both perforated and solid obturators. The relative advantages and disadvantages of each are discussed. Data obtained from these starting experiments enhance the understanding of the ram accelerator, as well as assist in the validation of unsteady, chemically reacting CFD codes.

  20. Electron microscopic observations on the epithelium of ram seminal vesicles.

    PubMed Central

    Plöen, L

    1980-01-01

    The ultrastructure of the secretory cells of the ram seminal vesicle was studied on material fixed by immersion or by vascular perfusion. The signs of apocrine secretion seen after immersion fixation did not appear after perfusion fixation and are therefore interpreted as artefacts. Instead, vacuoles with a granule in them were seen. Such vacuoles were observed in the Golgi apparatus and in the apical cytoplasm. Further indications of merocrine secretion were also found. It therefore appears that protein secretion in the ram seminal vesicle follows the typical pattern of serous glands. The possibility that fructose is extruded with the protein as the vacuoles open at the luminal cell surface is discussed. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:7410195