2,209 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
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
Staff development as a factor of competitiveness increase oil and gas industry
Currently, personnel policy in the Russian Federation oil and gas sector needs to be modernized. Previous management systems outdated in most cases. The necessity of raising funds in such areas as human resources management: training, motivation and retraining, as well as interaction with schools and universities. The proposed rationalization measures should serve as a stimulus for the development of staff, as well as lead to significant changes in the formation of the branch system, improving performance and growth of highly qualified personnel in the oil and gas industry. After completing these steps, Russian oil companies can increase their competitive advantage in the global market and increase the attractiveness of the oil and gas industry
Liquid-injection atomic layer deposition of TiOx and Pb-Ti-O films
Pb-Ti-O films were prepared by liquid-injection atomic layer deposition (ALD) using H2O as oxygen source after evaluating Ti precursors with different beta-diketonate type ligands, Ti(OC3H7)(2)(C11H19O2)(2) [Ti(Oi-Pr)(2)(DPM)(2)] and Ti(OC5H11)(2)(C10H17O2)(2) [Ti(Ot-Am)(2)(IBPM)(2)], dissolved in ethylcyclohexane. For both Ti precursors, the apparent thermal activation energy of the deposition rate of TiOx films increased at a deposition temperature of about 380 degrees C, and the deposition rate of TiOx films grown at 300 degrees C saturated against the volume of injected Ti precursors. Ti(Oi-Pr)(2)(DPM)(2) was selected for the subsequent Pb-Ti-O film deposition because of its high precursor efficiency and the low temperature dependence of the deposition rate. Pb-Ti-O films were prepared using Ti(Oi-Pr)(2)(DPM)(2) and Pb(C12H21O2)(2) [Pb(TMOD)(2)] at deposition temperatures of 240 and 300 degrees C. The deposition rates of Pb and Ti in the Pb-Ti-O process were higher than those in binary PbO and TiOx processes under the same deposition conditions. The deposition rate of Pb in the Pb-Ti-O process showed a linear increase in response to the injected Pb precursor volume, which was different from the saturated deposition rate of the PbO process. The interface chemistry between the precursors and predeposited cation layers has critical impact on the self-regulated growth mechanism in the multicomponent oxide ALD. (c) 2006 The Electrochemical Society
Hafnium carbide formation in oxygen deficient hafnium oxide thin films
On highly oxygen deficient thin films of hafnium oxide (hafnia, HfO)
contaminated with adsorbates of carbon oxides, the formation of hafnium carbide
(HfC) at the surface during vacuum annealing at temperatures as low as 600
{\deg}C is reported. Using X-ray photoelectron spectroscopy the evolution of
the HfC surface layer related to a transformation from insulating into
metallic state is monitored in situ. In contrast, for fully stoichiometric
HfO thin films prepared and measured under identical conditions, the
formation of HfC was not detectable suggesting that the enhanced adsorption
of carbon oxides on oxygen deficient films provides a carbon source for the
carbide formation. This shows that a high concentration of oxygen vacancies in
carbon contaminated hafnia lowers considerably the formation energy of hafnium
carbide. Thus, the presence of a sufficient amount of residual carbon in
resistive random access memory devices might lead to a similar carbide
formation within the conducting filaments due to Joule heating
Applicability of Well-Established Memristive Models for Simulations of Resistive Switching Devices
Highly accurate and predictive models of resistive switching devices are
needed to enable future memory and logic design. Widely used is the memristive
modeling approach considering resistive switches as dynamical systems. Here we
introduce three evaluation criteria for memristor models, checking for
plausibility of the I-V characteristics, the presence of a sufficiently
non-linearity of the switching kinetics, and the feasibility of predicting the
behavior of two anti-serially connected devices correctly. We analyzed two
classes of models: the first class comprises common linear memristor models and
the second class widely used non-linear memristive models. The linear memristor
models are based on Strukovs initial memristor model extended by different
window functions, while the non-linear models include Picketts physics-based
memristor model and models derived thereof. This study reveals lacking
predictivity of the first class of models, independent of the applied window
function. Only the physics-based model is able to fulfill most of the basic
evaluation criteria.Comment: 9 pages; accepted for IEEE TCAS-
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