The oxidation of titanium silicide

This paper investigates the morphology changes that occur with the oxidation of a ti-tanium silicide—polysilicon system. These changes were studied as a function of poly-silicon doping and silicide formation parameters. Emphasis was placed on transmission electron microscopy studies of the samples by planar and cross sectional techniques. Various surface analysis methods have also been used to characterize the films. This study helps to define the possible use and shortcomings of a self aligned titanium silicide insulator. The results show that varying quality insulators result, dependent largely on the initial conditions of the titanium silicide. After oxidation the Auger and TEM anal-ysis show that in all cases some form of silicon dioxide was created, but typically a considerable amount of titanium oxide was also present. For instance, it was apparent that more titanium oxide formed on the samples RTA’ed for 1 min at 700° C than the 5 min at 800° C and considerably more on the arsenic doped sample than the boron doped. The silicide also had morphology changes as the result of the oxidation. There was a phase change from the C49 to C54 phase for the 1 min at 700° C samples as would be expected at the time and temperature of the oxidation. There also was a sig-nificant amount of agglomeration and epitaxial growth observed. Further work is re-quired to completely characterize these phenomena.     

Microwave active resonator band-pass filters in various mmic technologies

In this article, two topologies of L-C parallel active resonators are presented. These circuits are realized in MMIC technology, using three transistors which could be MESFET, hemt or HBT. The survey of these resonators shows the possibility, by controling the values of a resistor and/or a capacitor, on the one hand, to tune the resonance frequency of these circuits, and on the other hand, to cancel out their losses so as to obtain negative conductance. Compact, lossless and narrow-band filters are then implemented using previous active resonators. To date, the use of mesfet technology has reduced the synthesis of such active filters in S-band and at X-band low frequencies. Now, however, hemt and HBT technologies allow the extension of their implementation to the whole X-band. This survey is illustrated by the simulated response of a 10 GHz filter with a 500 MHz 3 dB bandwidth. The mmic technology is a 0.2 μm hemt one. The simulated performances of this filter achieve a mean transmission gain of 0. 5 dB, with a reflection loss higher than 10 dB at 10 GHz,     

A Broadband CPW-to-Microstrip Modes Coupling Technique

A broadband vertical transition from coplanar waveguide (CPW)-to-microstrip modes is presented. The transition has a double resonance and can be tuned for very wide-band operation. The CPW-to-microstrip modes coupling technique is useful for the vertical integration of multi-layer millimeter-wave circuits, packaging and antenna feeding networks. A vertical transition has been fabricated on 100 μm silicon substrate for operation at W-band frequencies and shows less than 0.3 dB of insertion loss and better than 12 dB of return loss from 75 to 110 GHz. A 94 GHz CPW-fed microstrip antenna showing a 10-dB bandwidth of about 30 % has been built using the same transition technique.     

Stress-strain relationships in uniaxial extension of high cis-1,4-polyisoprene networks with different molecular weight precursors

Equilibrium stress-strain relationships in uniaxial extension for high cis-1,4-polyisoprene (Shell IR 307) networks were obtained by extrapolation of relaxation measurements to infinite time through a BKZ constitutive equation. Three series of networks were investigated, each series being characterized by its polymer precursor molecular weight. Influence of crosslinking density was studied through varying amounts of dicumyl peroxide as crosslinking agent. These results were used to test Flory and Erman's recent molecular elasticity theory of imperfect networks with constraints on junctions. It was shown that this later theory treating entanglements as restrictions on junction fluctuations could be reasonably used to characterize network topology. A universal value of 0.50 for the interpenetration parameter I is confirmed and an interpretation of parameter ζ in terms of network inhomogeneity is tentatively given.     

Monoepoxy polymerization initiated by BF3-amine complexes in bulk. III. Influence of γ-butyrolactone on polymer formation

The influence of γ-butyrolactone (γ-BL), used as solvent of BF₃-amine complexes, on the polymerization of monoepoxides was studied. Different intermediate reaction products of PGE initiated by BF₃-4-methoxyaniline (BF₃-4MA) previously solubilized in γ-BL (55% by weight), were separated and analyzed by ¹H-NMR. It is shown that there is the opening of both epoxy and γ-BL. The latter does not homopolymerize, but copolymerizes well with epoxy groups. The use of a large quantity of γ-BL leads to a decreasing molar mass of the formed polymer. The kinetic study allowed to propose the mechanism of the cationic polymerization of epoxy initiated by BF₃-amine complex in the presence of γ-BL. © 1994 John Wiley & Sons, Inc.     

Hardness and fracture toughness of thermoelectric La<Subscript>3−<Emphasis Type="Italic">x</Emphasis></Subscript>Te<Subscript>4</Subscript>

Lanthanum telluride (La_3?x Te₄) is a state-of-the-art n-type high temperature thermoelectric material that behaves as a weak and brittle ceramic. Vickers microindentation hardness testing was explored as a rapid analysis technique to characterize the mechanical properties of this material. An indentation size effect was observed with hardness values ranging from 439 ± 31 kgf/mm² (0.01 kgf/10 s contact time) to 335 ± 6 kgf/mm² (0.5 kgf/10 s contact time). The Vickers indentation fracture toughness, K _VIF, based on measurements of crack lengths emanating from the corners of the Vickers indents was 0.70 ± 0.06 MPa m^1/2.     

Quantifying Precision and Availability of Location Memory in Everyday Pictures and Some Implications for Picture Database Design.

The authors investigated whether memory for object locations in pictures could be exploited to address known difficulties of designing query languages for picture databases. M. W. Lansdale's (1998) model of location memory was adapted to 4 experiments observing memory for everyday pictures. These experiments showed that location memory is quantified by 2 parameters: a probability that memory is available and a measure of its precision. Availability is determined by controlled attentional processes, whereas precision is mostly governed by picture composition beyond the viewer's control. Additionally, participants' confidence judgments were good predictors of availability but were insensitive to precision. This research suggests that databases using location memory are feasible. The implications of these findings for database design and for further research and development are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)