Low leakage stoichiometric SrTiO3 dielectric for advanced metal–insulator–metal capacitors

Metal–insulator–metal capacitors (MIMCAP) with stoichiometric SrTiO₃ dielectric were deposited stacking two strontium titanate (STO) layers, followed by intermixing the grain determining Sr‐rich STO seed layer, with the Ti‐rich STO top layer. The resulted stoichiometric SrTiO₃ would have a structure with less defects as demonstrated by internal photoemission experiments. Consequently, the leakage current density is lower compared to Sr‐rich STO which allow further equivalent oxide thickness downscaling.

Schematic of MIMCAP with stoichiometric STO dielectric formed from bottom Sr‐rich STO and top Ti‐rich STO after intermixing during crystallization anneal.     

Decomposition of the Space of Regular Operators

Let E be a directed vector space with the Riesz decomposition property and F be a complete v?ctor lattice. It is proved that if G is a solid subspace of E then the subspace of all regular operators annihilating on G is a component in the space of all regular operators from E into F.¹²     

Vibrational mode selectivity in hyperfine interactions: polarization quantum beat spectroscopy of HCF(A1A")

We report on the vibrational mode dependence of the 19F and 1H hyperfine interaction constants in the A1A" state of HCF, determined using polarization quantum beat spectroscopy. The nuclear spin/overall rotation coupling constants display a pronounced energy dependence and mode selectivity which can be traced to variations in both the A rotational constant and nuclear spin/electron orbital coupling constant a. In particular, modes containing C-F stretching excitation display significantly larger 19F spin-rotation constants, which is explained in terms of a decrease in back donation of electron density into the C 2p(pi) orbitals.     

Template synthesis and crystal structure of an asymmetric square-planar complex: Pyridine-2,6-dicarbaldehyde-bis(<Emphasis Type="Italic">S</Emphasis>-methylisothiosemicarbazonato)nickel(II) iodide

The asymmetric complex [Ni(HL)]I (where H₂L is pyridine-2,6-dicarbaldehyde-bis(S-methylisothiosemicarbazone)) is synthesized by the [2 + 1] template condensation of S-methylisothiosemicarbazide hydroiodide with pyridine-2,6-dicarbaldehyde in the presence of nickel(II) acetate. The crystal structure of the [Ni(HL)]I complex (where HL is C₁₁H₁₄N₇S₂) is determined using X-ray diffraction. The square-planar coordination of the nickel(II) central atom is provided by four N donor atoms of the chelating ligand, namely, one N atom of the pyridine residue and three N atoms of the isothiosemicarbazide fragments. The deprotonated isothiosemicarbazide fragment in the imino form and the neutral ammonium isothiosemicarbazide fragment differ in the degree of deprotonation, the mode of coordination to the central atom (N¹N³ and N², respectively), and the conformation (E and Z, respectively). The structural features of the ammonium isothiosemicarbazide fragment are associated with the formation of zwitterions. It is established that the crystal structure of the compound under investigation contains centrosymmetric dimers. These dimers participate in the formation of the second coordination sphere N₄S of the central atom.     

Decomposition of generalized vector variational inequalities

A multicriteria optimization problem is called Pareto reducible if its weakly efficient solutions actually are efficient solutions for the problem itself or for at least one subproblem obtained from it by selecting certain criteria. The aim of this paper is to investigate a similar property within a special class of generalized vector variational inequalities, under appropriate generalized convexity assumptions.     

Enhancements on the Hyperplanes Arrangements in Mixed-Integer Programming Techniques

This paper is concerned with improvements in constraints handling for mixed-integer optimization problems. The novel element is the reduction of the number of binary variables used for expressing the complement of a convex (polytopic) region. As a generalization, the problem of representing the complement of a possibly not connected union of such convex sets is detailed. In order to illustrate the benefits of the proposed improvements, a typical control application, the control of multiagent systems using receding horizon optimization techniques, is considered.     

On Directed Sets and their Suprema

The aim of this paper is to investigate partially ordered real linear topological spaces in which directed sets admit a supremum in their closure. In particular, we point out that this property is intimately related to the normality of the ordering cone and also to the Scott continuity of functionals belonging to the nonnegative polar of the ordering cone. Research of Mohamed Ait Mansour was supported by LACO (Laboratoire d'Arithmétique, Calcul Formel et Optimisation), UMR-CNRS 6090, University of Limoges and Agence Universitaire de la Francophonie.     

PLD of Fe3O4 thin films: Influence of background gas on surface morphology and magnetic properties

Ablation of Fe₃O₄ targets has been performed using a pulsed UV laser (KrF, λ = 248 nm, 30 ns pulse duration) onto Si(100) substrates, in reactive atmospheres of O₂ and/or Ar, with different oxygen partial pressures. The as-deposited films were characterised by atomic force microscopy (AFM), X-ray diffraction (XRD), conversion electron Mössbauer spectroscopy (CEMS) and extraction magnetometry, in order to optimise the deposition conditions in the low temperature range. The results show that a background mixture of oxygen and argon improves the Fe:O ratio in the films as long as the oxygen partial pressure is maintained in the 10⁻² Pa range. Thin films of almost stoichiometric single phase polycrystalline magnetite, Fe_2.99O₄, have been obtained at 483 K and working pressure of 7.8 × 10⁻² Pa, with a high-field magnetization of ∼490 emu/cm³ and Verwey transition temperature of 112 K, close to the values reported in the literature for bulk magnetite.     

Phthalonitrile‐containing aromatic polyimide thin films with nano‐actuation properties

Polymer films of some polyimides containing pendant phthalonitrile groups were prepared by casting the corresponding poly(amic acid) solutions onto glass plates, followed by thermal imidization under controlled temperature conditions. The poly(amic acid)s were synthesized by polycondensation reaction of 4,4′‐diamino‐4″‐(3,4‐dicyanophenoxy)triphenylmethane, 1, or of different amounts of 1 and 4,4′‐bis(4‐aminophenoxybiphenyl), with two aromatic dianhydrides, 4,4′‐oxydiphthalic anhydride or benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride. Most of the films were flexible and tough and exhibited high thermal stability, having the initial decomposition temperature above 400 °C. Dynamic mechanical analysis and dielectric spectroscopy revealed the influence of phthalonitrile group content on the relaxation processes of polyimides. The values of the dielectric constant at 10 kHz and 20 °C were in the range of 3.25–3.61. The films exhibited nano‐actuation in the range of 240–480 nm, depending on the phthalonitrile group content, when an electric voltage was applied on their surface. Copyright © 2012 John Wiley & Sons, Ltd.