Reliability of gate dielectrics and metal–insulator–metal capacitors

In this review paper reliability characterisation methods of SiO₂ as gate dielectric and metal–insulator–metal capacitors with various dielectrics are discussed. It includes the test structure design, the stress and measurement sequences, the raw data analysis and the extrapolation models of measured time to breakdown to lifetimes at operating conditions and targeted product failure rates. For each topic various references are given where further details are described. Especially pitfalls of approaches and problem areas are highlighted.     

德国桥面防水系统——桥面防水目标、方法以及应用材料

介绍了德国桥面防水的历史、桥面防水的目的及必要性和中国桥面防水现状及弊病,并对德国威达桥面专用防水系统及桥面专业防水卷材作了详细阐述.     

Photo-carrier radiometry of semiconductors: A novel powerful optoelectronic diffusion-wave technique for silicon process non-destructive evaluation

Laser-induced infrared photo-carrier radiometry (PCR) is introduced as an emerging semiconductor NDT technology, both theoretically and experimentally through deep sub-surface scanning imaging and signal frequency dependencies from Si wafers. PCR completely obliterates the thermal infrared emission band (8–12 μm), unlike the known photothermal signal types, which invariably contain combinations of carrier-wave and thermal-wave infrared emissions due to the concurrent lattice absorption of the incident beam and non-radiative heating. The PCR theory is presented as infrared depth integrals of carrier-wave (CW) density profiles. Experimental aspects of this new methodology are given, including the determination of photo-carrier transport parameters (surface recombination velocities, carrier diffusion coefficients, recombination lifetimes and carrier mobilities) through modulation frequency scans. CW scanning imaging is also introduced. High-frequency, deep-defect PCR images thus obtained prove that very-near-surface (where optoelectronic device fabrication takes place) photo-carrier generation can be detrimentally affected not only by local electronic defects as is commonly assumed, but also by defects in remote wafer regions much deeper than the extent of the electronically active thin surface layer.     

Dihedral Angle Effects on the Stability of Pore Channels

The modifying effect of dihedral angle on the morphological stability of continuous pore channels along three-grain junctions was evaluated and quantified. Breakdown of a continuous pore channel is possible when perturbation wavelengths exceed a critical wavelength, λ_min, which is found to depend on dihedral angle. The implications of the analysis to microstructure development during sintering are briefly discussed.     

On the influence of coarsening on microsegregation

An analytical treatment of the influence of coarsening by ripening on microsegregation is presented. Comparison of results from the model with data on Al-4.5 wt pct Cu and Sn-Bi alloys indicates that an overestimation of the reduction in microsegregation results if it is assumed that ripening proceeds throughout the solidification range. This is attributed to the changing nature of coarsening processes, in which coalescence processes predominate over ripening at higher volume fractions solid.     

Impedance characterization and modeling of electrodes for biomedical applications

A low electrode-electrolyte impedance interface is critical in the design of electrodes for biomedical applications. To design low-impedance interfaces a complete understanding of the physical processes contributing to the impedance is required. In this work a model describing these physical processes is validated and extended to quantify the effect of organic coatings and incubation time. Electrochemical impedance spectroscopy has been used to electrically characterize the interface for various electrode materials: platinum, platinum black, and titanium nitride; and varying electrode sizes: 1 cm2, and 900 microm2. An equivalent circuit model comprising an interface capacitance, shunted by a charge transfer resistance, in series with the solution resistance has been fitted to the experimental results. Theoretical equations have been used to calculate the interface capacitance impedance and the solution resistance, yielding results that correspond well with the fitted parameter values, thereby confirming the validity of the equations. The effect of incubation time, and two organic cell-adhesion promoting coatings, poly-L-lysine and laminin, on the interface impedance has been quantified using the model. This demonstrates the benefits of using this model in developing better understanding of the physical processes occurring at the interface in more complex, biomedically relevant situations.     

Viscoelastic properties of a new in situ gelling thiolated chitosan conjugate

The aim of this study was the synthesis of a new thiolated chitosan conjugate and the evaluation of its viscoelastic properties in vitro. The modification of chitosan was achieved by covalent attachment of isopropyl-S-acetylthioacetimidate to chitosan. The resulting conjugate (chitosan-TEA; chitosan-thioethylamidine) exhibited 300.7+/-27.4 micromol thiol groups per gram polymer and no disulfide bond. For rheological studies, the pH of 0.5% and 1% polymer solutions was adjusted to 6.5 in order to simulate a physiological pH-level. Both, 0.5% and 1% chitosan-TEA solutions showed the transition from sol to gel within 30 min. Within 6 h of incubation, the storage modulus of 0.5% and 1% chitosan-TEA increased 3354-fold and 6199-fold, whereas the loss modulus increased 11-fold and 38-fold, respectively. Frequency sweep measurements demonstrated an increase in crosslinking of the thiolated polymer as a function of time. The formation of inter- and/or intramolecular disulfide bonds was monitored indirectly via determining the decrease of thiol groups. Unmodified chitosan did not exhibit in situ gelling properties. The release of a fluorescent marker being incorporated in a 0.5% chitosan-TEA solution was significantly (p<0.001) slower, when the formulation was preincubated for one hour and consequently already highly crosslinked. The polymer generated within this study represents a promising novel tool for various drug delivery systems, where in situ gelling properties are advantageous.     

Trace element analysis of scales from four populations of Norwegian Atlantic salmon (Salmo salar L.) for stock identification using laser ablation inductively coupled plasma mass spectrometry

The pre-smolt stage of the scale of adult Norwegian Atlantic salmon from four populations, encompassing both farmed and wild hatchery stocks, has been analyzed by laser ablation inductively coupled plasma mass spectrometry (LA-HR-ICP-MS). The purpose of this study was to test for differences in elemental composition between stocks of Atlantic salmon that have lived in separate fresh water locations until the smoltification and natural run out or transportation to the sea-cages. The populations studied were from fish farms located at Bremanger and Sorfold, a cultivated stock from Mossa, and one wild local stock from the river Gaula. The following elements were included in the analytical protocol: Li, Mg, Ca, Cr, Mn, Fe, Zn, Sr, Ba, Pb, and U. Calcium was used as a natural internal standard. Classification of the analytical data is studied by multivariate statistical techniques such as principal component analysis (PCA). We have been able to delineate the population of Atlantic salmon (Salmo salar L.) from Gaula and Mossa from the Bremanger and the Sorfold stock based on the ten elements analyzed. The Bremanger and Sorfold stocks were partially delineated. The differences in elemental composition in the scales, which makes the delineating of the four stocks possible, probably reflects geological differences in the bedrock at the four fresh water locations experienced by the salmon during the pre-smolt stage.     

Quantitative determination of combustion intermediates with cavity ring-down spectroscopy: systematic study in propene flames near the soot-formation limit

Cavity ring-down spectroscopy (CRDS) was applied in several fuel-rich, one-dimensional, premixed C3H6/O2/Ar flames at 50 mbars (37.5 torr) to measure absolute OH, HCO, and 1CH2 concentration as well as temperature as a function of stoichiometry. Although these flames near the sooting limit present a complex chemical environment, significant spectral interferences were found to be absent. Specific aspects of the CRDS technique for measurement of temperature and radical concentration profiles are discussed; and the results are analyzed in comparison with flame model simulations.