Contents to Volume 123 (2000)

Authors Index

Contents to Volume 123 (2000)     

A Compact Model for Valence-Band Electron Tunneling Current in Partially Depleted SOI MOSFETs

The valence-band electron (EVB) tunneling current in partially depleted silicon-on-insulator (SOI) MOSFETs increases as the gate oxide gets thinner and affects the dynamic behavior of devices and circuits. We present an engineering model of EVB tunneling current based on the surface-potential formulation. The new model is implemented in a SOI MOSFET compact model and is used to study the impact of EVB tunneling on circuit performance. Simulations of stacked logic gates show that the EVB tunneling current not only boosts circuit switching speed but also mitigates the history dependence of propagation delays     

Infrared spectroscopy of self-assembled monolayer films on silicon

Infrared vibrational spectroscopy in an attenuated total reflection (ATR) geometry has been employed to investigate the presence of organic thin layers on Si-wafer surfaces. The phenomena have been simulated to show there can be a field enhancement with the presented single-reflection ATR (SR-ATR) approach which is substantially larger than for conventional ATR or specular reflection. In SR-ATR, a discontinuity of the field normal to the film contributes a field enhancement in the lower index thin film causing a two order of magnitude increase in sensitivity. SR-ATR was employed to characterize a single monolayer of undecylenic acid self-assembled on Si(1 1 1) and to investigate a two monolayer system obtained by adding a monolayer of bovine serum albumin protein.     

Solid State Structures and Solution Dynamics of Unsolvated and Diethyl Ether Solvated Dilithium N,N'-Bis(trimethylsilyl)ethylenediamide Complexes

The lithiation of N,N'-bis(trimethylsilyl)ethylenediamine, 1, by 2 equiv of methyllithium in diethyl ether yields the dimeric diethyl ether adduct [{Li[N(SiMe(3))CH(2)CH(2)NSiMe(3)]Li.OEt(2)}(2)], 2. Recrystallization of 2 from benzene gives quantitatively the unsolvated trimer [{Li[N(SiMe(3))CH(2)CH(2)NSiMe(3)]Li}(3)], 3. The solution dynamics of 2 and 3 in toluene have been investigated using variable temperature multinuclear NMR spectroscopy. In solution, 2 is undergoing a rapid exchange process involving an equilibrium between unsolvated and diethyl ether solvated dimers, whereas compound 3 exists in a temperature dependent equilibrium of dimeric and trimeric species, of which the trimer is fluxional and exchanges inequivalent ligands by an intramolecular distortion of the Li(6)N(6) cage structure. Crystals of 2 are monoclinic, of space group P2(1)/n (No. 14), with a = 10.692(9) ?, b = 16.192(2) ?, c = 24.04(4) ?, beta = 101.16(5) degrees, V = 4083(8) ?(3), and Z = 4. Crystals of 3 are trigonal, of space group R&thremacr;m(No. 166), a = 17.765(1) ?, c = 13.394(1) ?, V = 3660.5(5) ?(3), Z = 3.     

Zero-field splittings in aromatic triplet states

The zero-field splitting parametersD andE have been calculated for naphthalene using T.B.M. and I. R. M. wave functions, and accurate values of all significant two, three and four centre dipolar interaction integrals. Agreement with experiment is improved in the case ofE, but is less satisfactory forD.     

Bis­[μ‐3{5}‐(2‐pyridyl)­pyrazolido]­bis­[(aceto­nitrile)copper(II)] diperchlorate

The title compound, [Cu₂(C₈H₆N₃)₂(C₂H₃N)₂](ClO₄)₂, con­tains a centrosymmetric dinuclear dication, with square‐pyrami­dal Cu^II centres linked by two 1,2‐pyrazolide bridging groups. There is a weak apical interaction between each Cu ion and a perchlorate O atom.     

Synthesis and self-assembly of "tree-like" amphiphilic glycopolypeptides

Novel synthetic tree-like oligosaccharides-grafted-polypeptides were prepared by using Huisgen 1,3-dipolar cycloaddition between poly(γ-benzyl-L-glutamate)-block-poly(propargylglycine) and two different oligosaccharides, dextran or hyaluronan. By direct solubilisation in water, these tree-like glycopeptides spontaneously form very small assemblies with sizes below 50 nm and low polydispersity.     

Vortex fluidic exfoliation of graphite and boron nitride

Graphite is exfoliated into graphene by shearing vortex fluidic films of N-methyl-pyrrolidone (NMP), as a controlled process for preparing oxide free graphene, and for exfoliating the corresponding boron nitride sheets.     

Reactions of uranium atoms with ammonia: infrared spectra and quasi-relativistic calculations of the U:NH3, H2N--UH, and HN==UH2 complexes

Ammonia molecules interact with U atoms, and the resulting U:NH3 complex rearranges upon visible irradiation to form the H2N--UH and HN==UH2 molecules in excess argon. These products are identified by functional group frequencies, 15NH3 and ND3 isotopic shifts, and comparison to frequencies calculated by using density functional theory. The N==U pi bond in HN==UH2 is enhanced by partial triple-bond character through N(2p) to U(5f) conjugation, which is comparable to that found in the analogous HN==ThH2 molecule. These products also form complexes with additional ammonia molecules in the matrix. The interesting higher-energy N[triple chemical bond]UH3 complex is not formed.