Temperature and field dependence of stress induced leakage currents in very thin (<5 nm) gate oxides

We have studied the electric field and temperature dependence of stress induced leakage currents that appear in 3.8 and 4.7 nm thick SiO₂ oxides of metal oxide semiconductor structures after Fowler–Nordheim (FN) electron injections from the poly-Si gate and localized hot-hole injections from the p-Si substrate. Constant voltage or constant current stressing modes were used, which did not produce any difference in stress induced leakage currents (SILC) increase. A Schottky law apparently fits the field dependence of such currents in 4.7 nm samples, but the slope found in 3.8 nm thick oxides disagrees with the theoretical prediction. Moreover, the field dependence of the thermal activation energy found is much less than the Schottky prediction, which rules out the possibility of a thermoionic process to fully explain such currents in our samples. We show that a direct tunneling law, modified to account for a mechanism assisted by stress induced baricentric neutral defects, does correctly fit the oxide field dependence of these currents and is consistent with the observed thermal activation energy.     

Electronic properties of 4,4',5,5'-tetramethyl-2,2'-biphosphinine (tmbp) in the redox series fac-[Mn(Br)(CO)3(tmbp)], [Mn(CO)3(tmbp)]2, and [Mn(CO)3(tmbp)](-): crystallographic,spectroelectrochemical, and DFT computational study

Stepwise electrochemical reduction of the complex fac-[Mn(Br)(CO)(3)(tmbp)] (tmbp = 4,4',5,5'-tetramethyl-2,2'-biphosphinine) produces the dimer [Mn(CO)(3)(tmbp)](2) and the five-coordinate anion [Mn(CO)(3)(tmbp)](-). All three members of the redox series have been characterized by single-crystal X-ray diffraction. The crystallographic data provide valuable insight into the localization of the added electrons on the (carbonyl)manganese and tmbp centers. In particular, the formulation of the two-electron-reduced anion as [Mn(0)(CO)(3)(tmbp(-))](-) also agrees with the analysis of its IR nu(CO) wavenumbers and with the results of density functional theoretical (DFT) MO calculations on this compound. The strongly delocalized pi-bonding in the anion stabilizes its five-coordinate geometry and results in the appearance of several mixed Mn-to-tmbp charge-transfer/IL(tmbp) transitions in the near-UV-vis spectral region. A thorough voltammetric and UV-vis/IR spectroelectrochemical study of the reduction path provided evidence for a direct formation of [Mn(CO)(3)(tmbp)](-) via a two-electron ECE mechanism involving the [Mn(CO)(3)(tmbp)](*) radical transient. At ambient temperature [Mn(CO)(3)(tmbp)](-) reacts rapidly with nonreduced fac-[Mn(Br)(CO)(3)(tmbp)] to produce [Mn(CO)(3)(tmbp)](2). Comparison with the analogous 2,2'-bipyridine complexes has revealed striking similarity in the bonding properties and reactivity, despite the stronger pi-acceptor character of the tmbp ligand.     

On the dynamics of superfluid vorticity in non-dissipative processes

We investigate the consequences of the possible existence of superfluid vorticity on the Landau two-fluid equations. Assuming a conservation law for superfluid circulation, we show that in non-dissipative situations, the superfluid vorticity is swept along by the normal fluid.     

High-g accelerometer based on an in-fiber bragg grating sensor

An accelerometer based on an in-fiber Bragg grating sensor has been fabricated and demonstrated. The grating sensor operates linearly up to accelerations of 170,000g_n. The design, testing and performance of the accelerometer are discussed.     

PMR investigation of the structure of native and iodine doped polyacetylene films

The second moment of the proton magnetic resonance line of native cis- polyacetylene, thermally isomerized trans-polyacetylene, and iodine doped initially cis-polyacetylene has been measured by a pulse technique. The results differ qualitatively and quantitatively from previous reports. They are discussed in terms of the proposed crystalline structures of (CH)_x.     

N = 2 Supersymmetric Unconstrained Matrix GNLS Hierarchies are Consistent

We develop a pseudo-differential approach to the N = 2 supersymmetric unconstrained matrix (k|n, m)-generalized nonlinear Schrödinger hierarchies and prove consistency of the corresponding Lax-pair representation (nlin.SI/0201026). Furthermore, we establish their equivalence to the integrable hierarchies derived in the super-algebraic approach of the homogeneously-graded loop superalgebra ${sl(2k{+}n\vert 2k{+}m)\otimes C[{\lambda},{\lambda}^{-1}]}$ (nlin.SI/0206037). We introduce an unconventional definition of N = 2 supersymmetric strictly pseudo-differential operators so as to close their algebra among themselves.