8,058 research outputs found
A Complementary Resistive Switch-based Crossbar Array Adder
Redox-based resistive switching devices (ReRAM) are an emerging class of
non-volatile storage elements suited for nanoscale memory applications. In
terms of logic operations, ReRAM devices were suggested to be used as
programmable interconnects, large-scale look-up tables or for sequential logic
operations. However, without additional selector devices these approaches are
not suited for use in large scale nanocrossbar memory arrays, which is the
preferred architecture for ReRAM devices due to the minimum area consumption.
To overcome this issue for the sequential logic approach, we recently
introduced a novel concept, which is suited for passive crossbar arrays using
complementary resistive switches (CRSs). CRS cells offer two high resistive
storage states, and thus, parasitic sneak currents are efficiently avoided.
However, until now the CRS-based logic-in-memory approach was only shown to be
able to perform basic Boolean logic operations using a single CRS cell. In this
paper, we introduce two multi-bit adder schemes using the CRS-based
logic-in-memory approach. We proof the concepts by means of SPICE simulations
using a dynamical memristive device model of a ReRAM cell. Finally, we show the
advantages of our novel adder concept in terms of step count and number of
devices in comparison to a recently published adder approach, which applies the
conventional ReRAM-based sequential logic concept introduced by Borghetti et
al.Comment: 12 pages, accepted for IEEE Journal on Emerging and Selected Topics
in Circuits and Systems (JETCAS), issue on Computing in Emerging Technologie
Insulator-to-metal transition of SrTiO3:Nb single crystal surfaces induced by Ar+ bombardment
In this paper, the effect of Ar+ bombardment of SrTiO3:Nb surface layers is
investigated on the macro- and nanoscale using surface-sensitive methods. After
bombardment, the stoichiometry and electronic structure are changed distinctly
leading to an insulator-to-metal transition related to the change of the Ti "d"
electron from d0 to d1 and d2. During bombardment, conducting islands are
formed on the surface. The induced metallic state is not stable and can be
reversed due to a redox process by external oxidation and even by
self-reoxidation upon heating the sample to temperatures of 300{\deg}C.Comment: 4 pages, 4 figure
Lorentz and Polarization Correction for the Buerger Precession Method
In a previous publication it was shown that in the precession method the angular velocity with which the reciprocal lattice moves through the sphere of reflection is not constant and equal to the angular velocity of precession, but rather varies with the position of the precession axis, It attains its maximum or minimum value whenever this axis passes, respectively, through a vertical or a horizontal plane
Resistive Switching Assisted by Noise
We extend results by Stotland and Di Ventra on the phenomenon of resistive
switching aided by noise. We further the analysis of the mechanism underlying
the beneficial role of noise and study the EPIR (Electrical Pulse Induced
Resistance) ratio dependence with noise power. In the case of internal noise we
find an optimal range where the EPIR ratio is both maximized and independent of
the preceding resistive state. However, when external noise is considered no
beneficial effect is observed.Comment: To be published in "Theory and Applications of Nonlinear Dynamics:
Model and Design of Complex Systems", Proceedings of ICAND 2012 (Springer,
2013
RETURN ON INVESTMENT IN SOCIAL NETWORKS
This review focuses on electrochemical metallization memory cells (ECM), highlighting their advantages as the next generation memories. In a brief introduction, the basic switching mechanism of ECM cells is described and the historical development is sketched. In a second part, the full spectra of materials and material combinations used for memory device prototypes and for dedicated studies are presented. In a third part, the specific thermodynamics and kinetics of nanosized electrochemical cells are described. The overlapping of the space charge layers is found to be most relevant for the cell properties at rest. The major factors determining the functionality of the ECM cells are the electrode reaction and the transport kinetics. Depending on electrode and/or electrolyte material electron transfer, electro-crystallization or slow diffusion under strong electric fields can be rate determining. In the fourth part, the major device characteristics of ECM cells are explained. Emphasis is placed on switching speed, forming and SET/RESET voltage, R(ON) to R(OFF) ratio, endurance and retention, and scaling potentials. In the last part, circuit design aspects of ECM arrays are discussed, including the pros and cons of active and passive arrays. In the case of passive arrays, the fundamental sneak path problem is described and as well as a possible solution by two anti-serial (complementary) interconnected resistive switches per cell. Furthermore, the prospects of ECM with regard to further scalability and the ability for multi-bit data storage are addressed
Electrical current distribution across a metal-insulator-metal structure during bistable switching
Combining scanning electron microscopy (SEM) and electron-beam-induced
current (EBIC) imaging with transport measurements, it is shown that the
current flowing across a two-terminal oxide-based capacitor-like structure is
preferentially confined in areas localized at defects. As the thin-film device
switches between two different resistance states, the distribution and
intensity of the current paths, appearing as bright spots, change. This implies
that switching and memory effects are mainly determined by the conducting
properties along such paths. A model based on the storage and release of charge
carriers within the insulator seems adequate to explain the observed memory
effect.Comment: 8 pages, 7 figures, submitted to J. Appl. Phy
The Lorentz Factor for the Buerger Precession Method
The Lorentz factor for the Buerger precession method is derived. It turns out that the angular velocity of the motion of the reciprocal lattice through the sphere of reflection is not uniform as hitherto accepted. The Lorentz factor thus depends explicitly on all three cylindrical coordinates ξ, ζ, τ of the reciprocal lattice point under consideration and not on only as ξ and ζ
- …