Mesa and planar SiGe-HBTs on MBE-wafers

SiGe-HBTs have the potential for outstanding analog and digital or mixed-signal high frequency circuits widely based on standard Si technology. Here we review on MBE grown transistors and circuits. Processes and results of a research-like SiGe HBT and two possible production relevant HBT versions are presented. The high frequency results with f_max and f_T up to 120 GHz and a minimum noise figure of 0.9 dB at 10 GHz demonstrate the advantage of using MBE samples with steep and high base doping and high germanium contents. A comparison to the concept of reported low doped, low germanium and triangular profiled SiGe base layers, realized by UHV-CVD, is given. In addition, some circuit demonstrators of SiGe-ICs will be presented.     

Chromaticity contour map of the RGB cube: A simple algorithm

A simple algorithm (amenable to spreadsheets) is described for plotting a luminance contour map of the color gamut of an additive‐primary display given the chromaticities of its primaries and screen white. Each contour of the plot represents (in either r,g or x,y coordinates) the polygon of intersection of the RGB cube with a plane of constant Y. Each vertex on a contour is an intersection of 1 of the 12 edges of the RGB cube with the constant‐Y plane. Feasibility of an edge as a vertex of the polygon is tested through comparison of the computed r,g coordinates with functions of the luminosity coefficients of the primaries. By ordering the RGB‐cube edges in a particular way prior to scanning them for feasibility, one is guaranteed to retrieve the vertices of any constant‐Y polygon in convex order. This fact facilitates plotting of the polygons.     

Single-Step Granulation Method with Microwaves: Preliminary Studies and Pilot Scale Results

Common pharmaceutical excipients and compounds were dried either by a simple convection method or by a combined convection and microwave method in a static bed or by a combined microwave and vacuum method in a mixed bed. A simple placebo granulation was dried by an exclusive vacuum method and by a combined microwave and vacuum method in a mixed bed. The results were compared.     

Calculated and Experimental Estimation of Absorbed Mechanical Work in Deformation of Synthetic Fibres

Methods are proposed for obtaining the elastic and absorbed components of deformation and mechanical work expended in the region of a nondestructive mechanical effect from the stress-strain diagrams or by calculated prediction. The closeness of the values of the absorbed and correspondingly the elastic components obtained with the measured or predicted stress-strain diagram totally confirm the satisfactory reliability of modeling the physicomechanical properties of a fibre in the form of an integral equation in which the nonlinear-hereditary kernel analytically reflects the activating character of the mechanical effect combined with the concept of the deformation-time analogy in normalized form [5].     

Propagation of Isothermal Flame in the Low-Pressure Thermal Decomposition of Nitrogen Trichloride

The inhibition and promotion of isothermal NCl₃ flame by NOCl and H₂, respectively, are explained. The crossover from the isothermal mode of flame propagation to the thermal one is analyzed for NCl₃–He mixtures. Calculations based on a kinetic mechanism taking into account energy chain branching are performed, and qualitative agreement between the calculated and observed data is demonstrated. The one-dimensional problem of chain–thermal flame propagation by a chain reaction involving a nonlinear-branching step has two solutions corresponding, one corresponding the isothermal mode of flame propagation and the other corresponding to the chain–thermal one. Nonlinear chain branching shortens the time needed for thermal ignition and increases the flammability of the combustible mixture.     

Limit of validity of the moisture diffusivity for the study of moisture transfer inside terracotta

In order to know the limit of validity of the concept of hydrical diffusivity, D_W, we tried to validate the Boltzmann's method used to identify it. We show that for a medium strictly satisfying the equation of diffusion, the method gives quite good results with nevertheless some inaccuracies for the extreme values of water contents. For the real studied material, a backed clay, its identification becomes more difficult because of the dispersion of the wetting phenomenon observed for different specimens of the same material. We are showing that the mean behaviour of one sample is near to be the same as the more probable behaviour of all the samples. Otherwise the values of D_W determined for a wetting cannot be used to describe a drying process. It practical interest is then considerably reduced. In order to test the influence of the gas phase pressure effects on the behaviour of the material, we have determined all the parameters necessary to describe, numerically, wetting and drying processes without to resort to D_W. We noticed an overpressure of the gas phase inside the material due to drying. If the gas pressure effects are, numerically, switched off, we cannot notice any influence on water content profiles for this type of material.     

Characterization of charge trapping in submicrometer NMOSFET's bygate capacitance measurements

Trapping of net positive charge at low gate stress voltage, and of net negative charge at high gate stress voltage, is observed through changes in the gate-to-drain capacitance of the stressed junction. These observations can be explained in terms of electron trapping, hole trapping, and generation of acceptor-like interface states located in the upper half of the bandgap. Channel shortening is also observed and found to exhibit a logarithmic time dependence     

Determination of cycle nonproportionality coefficient

We propose a cycle nonproportionality coefficient for a broad class of complex cyclic paths, allowing us to establish a clear relationship between the geometry of the strain path and the maximum hardening level attainable in the material in the steady state for a fixed value of the maximum plastic or total strain range. We discuss the effectiveness of using the proposed cycle nonproportionality coefficient compared with analogous parameters familiar from the literature. Based on a previously developed version of the endochronic theory of plasticity, we have numerically modeled the behavior of a material for cyclic loading along different planar nonproportional paths.Translated from Problemy Prochnosti, Nos. 5–6, pp. 29–38, May–June, 1995.