Bismuth valence of Bi-Sr-Ca-Cu-O superconducting film has been studied by X-ray photoemission spectroscopy. As-grown highly oriented Bi-Sr-Ca-Cu-O 2223 single-phase films with various critical temperatures from 98 K to 66 K were prepared by changing the Bi content. The Bi 4f core level electron spectra are decomposed into two components. These components are assigned to BiO and to Bi2O3 which is located at an energy higher than the peak of BiO by about 1 eV. Then it was empirically determined that the critical temperature can be controlled by the Bi mean valence, and changes irrespective of the number of Cu-O planes. The critical temperature of the film increases with a decrease in the Bi mean valence which was calculated from the ratio of BiO/Bi2O3.

The electrical characteristics of gate dielectrics have been intensively studied. We examined four types of gate dielectrics: thermal oxide films formed in a pyrogenic steam ambient, those in a dry oxygen ambient, chemical vapor deposition (CVD) oxide films, and the thermal/CVD stacked oxide films. The effects of nitridation on oxide properties have been also systematically investigated using the nitrogen implantation technique. It is found that hot-carrier degradation can be improved by nitridation irrespective of the oxidation methods. This improvement is attributed to the suppression of interface state generation and the reduction in the number of electron traps in the oxide films. Our extensive investigation concludes that the nitridation of gate oxide films by nitrogen implantation is very promising for the improvement in reliability in spite of the difference in oxide formation methods.

From an analysis of the dispersion of indicator in steady laminar fluid flow, expressions are derived for the determination of flow in a straight tube in circumstances in which the familiar Stewart-Hamilton relations for indicator dilution do not generally apply, namely when the method of detection of the tagged blood flow depends on the density of the indicator in the system, as with x-ray videodensitometry. The analysis assumes no diffusion of indicator, and is carried out for arbitrary profiles of fluid flow velocity and tube cross-section. Injections of finite width and finite duration are considered, whereby the indicator is distributed over the tube cross-section either uniformly or in proportion to velocity. Spatial resolution of the detector is considered. A new method is proposed to utilise a priori information when the type of flow is known beforehand. The application of the results is illustrated by several examples for cases with laminar flow. The study is theoretical and is intended only as a first step towards the measurement of blood flow in the human circulation.

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A reconstruction technique to calculate accurate tomograms of a sample, at a voxel scale, from tomographic experiments that involve probe-sample interactions of any degree of complexity is proposed. The properties of the reconstruction technique that accomplish this are outlined. The first guess to the solution is calculated directly from the reconstructed experimental projection data. To improve the accuracy of the approximate solution at every iteration, projection data are calculated by simulating the tomographic experiment, rather than by using a projection matrix. Calculating the ratio of the reconstructed experimental projection data to the reconstructed simulated projection data provides correction factors at every voxel. The approximate solution is multiplied by these correction factors. This correction formulation is identical to that used in the image-space reconstruction algorithm technique. High spatial resolution and accurate solutions are achieved by not implementing any form of smoothing. Instead, a novel technique is used to reduce the noise in the tomograms substantially. We call this reconstruction technique the discretized image-space reconstruction algorithm. This reconstruction technique provides a means to calculate the mass density and elemental composition tomograms of microscopic samples properly, utilizing the wealth of information measured in scanning transmission ion microscopy and particle-induced x-ray emission tomography experiments. To demonstrate the efficacy of this reconstruction technique, examples of scanning transmission ion microscopy tomography experiments are presented.