Characterization of transient currents in HfO2 capacitors in the short timescale

We present a detailed experimental investigation of transient currents in HfO₂ capacitors in the short timescale. We show that the transient currents flowing through the capacitor plates when the gate voltage is reset to zero after a low voltage stress period follow a power-law time dependence t^−α (with α ? 1) over more than eight decades of time and down to the μs timescale. As transient currents in HfO₂ are largely increased with respect to the SiO₂ case, these results confirm that transient effects can be a severe issue for the successful integration of high-k dielectrics.     

Accident analysis in LMFBR fuel rods by the fenht code

This paper describes the fenht code capability related to the safety requirements in nuclear plants. The code solves the non-linear transient heat-transfer problem for the fuel element of a nuclear reactor, in order to simulate any accidental, operational and emergency power transient with arbitrary initial conditions. The temperature distribution in the fuel, gap and cladding is obtained by a finite-element technique based on minimizing the thermal potential with respect to the temperature vector at the nodes of the finite elements. The non-linear differential matricial equation is linearized by an iterative procedure and solved by the Crank—Nicholson method. Also the thermoelastic stresses in the cladding are valued, by the usual Hooke's law. The code has been applied to the analysis of two reference accidents (incidental power transients) occurring in a liquid-metal fast-breeder reactor (LMFBR); the results are reported and briefly discussed.     

Resistance change in memory structures integrating CuTCNQ nanowires grown on dedicated HfO2 switching layer

The present paper deals with the bipolar resistive switching of memory elements based on metal-organic complex CuTCNQ (copper-7,7’,8,8’-tetracyanoquinodimethane) nanowires grown on a dedicated HfO₂ oxide switching layer. Switching characteristics are explored either at millimeter scale on pad-size devices or at nanoscale by using conductive atomic force microscopy. Whatever the investigation scales, the basic memory characteristics appear to be controlled by copper ionic transport within a switching layer. This latter corresponds to either HfO₂ layer in pad-size devices or nanogap formed at nanoscale between the atomic force microscopy conductive tip and CuTCNQ surface. Depending upon the observation scale, the switching layer (either HfO₂ oxide or nanogap) acts as a matrix in which copper conductive bridges are formed and dissolved thanks to redox processes controlled in alternating applied bias voltages.     

Resistive switching characteristics of NiO films deposited on top of W or Cu pillar bottom electrodes

This paper demonstrates the feasibility of resistive switching memory elements integrating a nickel oxide film deposited on top of a pillar bottom electrode. The unipolar switching was investigated over a wide temperature range (25 to 125 °C) on samples integrating either W or Cu plugs with diameters ranging from 1 down to 0.18 μm. The switching characteristics and scaling trends of various fabricated memory elements were compared to select the best bottom electrode contact. It was shown that NiO layers deposited on top of W-plugs exhibited the most satisfactory electrical characteristics for future high density memory devices. Their reliability performances in terms of endurance and retention were subsequently studied by using either quasi-static or pulse programming modes. Set operations with short (10 to 20 ns) and low amplitude (around 2 V) voltage pulses were also demonstrated.     

A criterion for experimental validation of slip-flow models for incompressible rarefied gases through microchannels

This paper is devoted to analysing the friction factor for incompressible rarefied gas flow through microchannels. A theoretical investigation is conducted in order to underline the conditions for experimentally evidencing rarefaction effects on the pressure drop. It is demonstrated that for a fixed geometry of the microchannel cross-section, it is possible to calculate the minimum value of the Knudsen number for which the rarefaction effects can be observed experimentally, taking into account the uncertainties related to evaluation of the friction factor.     

Study of the interfaces in resistive switching NiO thin films deposited by both ALD and e-beam coupled with different electrodes (Si, Ni, Pt, W, TiN)

Thin NiO films, included in a metal/resistive oxide/metal (MRM) stack, are receiving great interest, as they exhibit resistive switching when subjected to an external applied field, and can thus be implemented in a resistive random access memory (ReRAM). The electrical switching characteristic is seen to depend on the NiO/metal coupling. Therefore a characterization of the interface between NiO and the electrode is vital to optimize and get insights on the switching phenomena. In this work we deposited NiO thin films by atomic layer deposition (ALD) at 300 °C and electron beam deposition (e-beam) at 40 °C on Si, Ni, Pt, W and TiN substrates and we characterized them with X-ray reflectivity (XRR), grazing incidence X-ray diffraction (GIXRD) and time of flight secondary ion mass spectrometry (ToF-SIMS). Depending on the growth process, we found an influence of the substrate on the NiO film roughness, which exhibits values in the 1.2-6.2 nm range. NiO electron density was 1.35-1.96 e⁻Å⁻³ spread around the nominal value of 1.83 e⁻ Å⁻³ for bulk cubic polycrystalline NiO. X-ray diffraction showed that NiO is polycrystalline in the cubic phase. ToF-SIMS profiles confirm NiO/Metal interface sharpness and the optimal uniformity of NiO layers. Intermixing phenomena are limited or absent and the presence of contaminants, such as C, F, and Cl is very low.     

INDIGO-DataCloud: a Platform to Facilitate Seamless Access to E-Infrastructures

This paper describes the achievements of the H2020 project INDIGO-DataCloud. The project has provided e-infrastructures with tools, applications and cloud framework enhancements to manage the demanding requirements of scientific communities, either locally or through enhanced interfaces. The middleware developed allows to federate hybrid resources, to easily write, port and run scientific applications to the cloud. In particular, we have extended existing PaaS (Platform as a Service) solutions, allowing public and private e-infrastructures, including those provided by EGI, EUDAT, and Helix Nebula, to integrate their existing services and make them available through AAI services compliant with GEANT interfederation policies, thus guaranteeing transparency and trust in the provisioning of such services. Our middleware facilitates the execution of applications using containers on Cloud and Grid based infrastructures, as well as on HPC clusters. Our developments are freely downloadable as open source components, and are already being integrated into many scientific applications.     

Effects of methylphenidate on cooperative responding in children with attention deficit-hyperactivity disorder.

The effects of methylphenidate on cooperative responding in children with attention deficit hyperactivity disorder were examined. During 1 of 2 alternating periods of a laboratory task, the child's button presses added points to a counter marked Your Earnings. During the 2nd period, cooperative and independent response options were available. Cooperative responses added points simultaneously to a counter marked Your Earnings and Other's Earnings. Concurrently available independent responses added points only to the counter marked Your Earnings. Time allocated to the cooperative response option was significantly decreased following acute administration of the 0.3 mg/kg and the 0.6 mg/kg methylphenidate doses as compared with placebo. Implications for understanding the behavioral mechanism of methylphenidate effects on social behavior are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acute effects of eltoprazine on aggressive and point-maintained responding of normal male participants: Phase I study.

Aggressive and point-maintained operant responding of normal male participants were measured during 7 25-min sessions conducted over 8-hr experimental days. Aggressive responding ostensibly subtracted points exchangeable for money from another participant. Aggressive responding was engendered by subtracting points from the participants and maintained by initiation of intervals free of point subtractions. Point subtractions presents to the participants were attributed to other persons. Participants earned points exchangeable for money on a 2nd response option. Placebo and 5, 10, or 20 mg of eltoprazine were administered orally, and peak effects of eltoprazine on operant response measures occurred at 3 hr. Aggressive and point-maintained responding was decreased following the 10- and 20-mg eltoprazine doses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)