One-dimensional structures of Bi2O3 synthesized via metalorganic chemical vapor deposition process

We have demonstrated the synthesis of one-dimensional (1D) structures of bismuth oxide (Bi₂O₃) by a reaction of a trimethylbismuth (TMBi) and oxygen (O₂) mixture at 450 °C. Scanning electron microscopy showed that the product consisted of 1D materials with width or diameters less than 1 μm and lengths up to several tens of micrometers. The X-ray energy dispersive spectroscopy revealed that the materials contained elements of Bi and O. The results of X-ray diffraction and selected area electron diffraction pattern indicated that the obtained Bi₂O₃ were crystalline with monoclinic structure.     

Fast solid-phase crystallization of amorphous silicon films on glass using low-temperature multi-step rapid thermal annealing

Effects of multi-step rapid thermal annealing of plasma-deposited amorphous silicon films on Corning 7059 glass are investigated. A three-step rapid thermal annealing for 10 s/step at 730° C after film deposition reduces the activation energy of electrical conductivity for silicon films from 0.64 to 0.51 eV and causes (111) grain growth with a size of 1500 Å, which is determined using scanning electron microscopy, Raman spectroscopy and X-ray diffractometry.     

Isotope Dependence of Superheavy Nucleus Formation Cross Section

The dynamical process in the superheavy nucleus synthesis is studied on the basis of the two-dimensional Smoluchowski equation. Special attention is paid to the isotope dependence of the cross section for the superheavy nucleus formation by means of making a comparison among the reaction systems of ^54Re＋204pb, ^56Re ＋206Pb, and ^58Fe＋^208Pb. It is found by this comparison that the formation cross section is very sensitive to the conditional saddle-point height and the neutron separation energy of the compound nucleus. Reaction systems with lower height of conditional saddle-point and smaller neutron separation energy are more favourable for the synthesis of the superheavy nucleus.     

(001) textured PbTiO3 thin films grown on redopingn-Si by metalorganic chemical vapor deposition under reduced pressure

(001) textured PbTiO₃ thin films have been deposited on (001) redopingn-Si substrates by metalorgnic chemical vapor deposition (MOCVD) under reduced pressure, and the film ferroelectricity has been measured using the substrate as bottom electrode directly. Besides this investigation, a set of analysis including AFM surface morphology, SEM cross section morphology, electron-probe element analysis, XRD 0-20 scan and high temperature X-ray diffraction have been carried out to study the microstructure and phase transition process of the PbTiO₃ thin film.     

Formation of periodic ring structures of relief and voids under laser vapor deposition of metallic films

The formation of periodic ring structures during laser-induced chemical vapor deposition of metals from metal carbonyl is observed experimentally and described by a theoretical model.     

Aluminium oxide thin films prepared by plasma-enhanced chemical vapour deposition

Thin films of aluminium oxide have been deposited on glass, quartz, Si(100), steel, nickel, and aluminium by plasma-enhanced chemical vapour deposition (PECVD) using aluminium acetylacetonate (Al(acac)₃) as precursor. The deposits are hard (up to 2370 HK) and show good adherence to the substrates. The influence of various experimental parameters on deposition rate, film composition and hardness has been studied. The bias turned out to be the most effective parameter.On leave from Beijing Solar Energy Research Institute, Beijing, P.R. China     

Film growth mechanism of photo-chemical vapor deposition

The photo-chemical vapor deposition (CVD) of SiO₂ and SiN _x were investigated using 185 nm light of a low pressure mercury lamp. The film thickness deposited on the substrate was the function of the distance from the substrate to the light source and its relation was investigated by changing the reaction pressure. From these investigations, the space migration length of the active species was estimated, which was, at the processing pressure of 400 Pa, 10–20 mm. This migration length was confirmed by a model calculation. The step coverage of the film was investigated by the use of a two-dimensional capillary cavity. It was shown that the thickness decayed exponentially with the depth in the cavity. The decay constant did not show temperature dependence. From this result, the surface migration of the active species produced by photo-CVD was reported. To confirm this migration we presented a substrate-size effect of photo-CVD, which became obvious when the substrate size became smaller than the space migration length of the active species. From these results, the film growth mechanism of photo-CVD was discussed.Main parts of this paper were presented at the Material Research Society Fall Meeting at Boston 1987     

CO2 laser-induced plasma CVD synthesis of diamond

2 laser maintenance of a stationary optical discharge in a gas stream, exhausting over a substrate into the air (laser plasmatron). Nano- and polycrystalline-diamond films were deposited on tungsten substrates from atmospheric-pressure Xe(Ar):H₂:CH₄ gas mixtures at flow rates of 2 ?/min. A 2.5-kW CO₂ laser focused beam produced plasma. The deposition area was about 1 cm² and growth rates were up to 30–50 μm/h. Peculiarities and advantages of laser plasmatrons are discussed. Received: 15 January 1998/Accepted: 16 January 1998     

Measuring statistical heterogeneity: The Pietra index

There are various ways of quantifying the statistical heterogeneity of a given probability law: Statistics uses variance — which measures the law’s dispersion around its mean; Physics and Information Theory use entropy — which measures the law’s randomness; Economics uses the Gini index — which measures the law’s egalitarianism. In this research we explore an alternative to the Gini index-the Pietra index-which is a counterpart of the Kolmogorov-Smirnov statistic. The Pietra index is shown to be a natural and elemental measure of statistical heterogeneity, which is especially useful in the case of asymmetric and skewed probability laws, and in the case of asymptotically Paretian laws with finite mean and infinite variance. Moreover, the Pietra index is shown to have immediate and fundamental interpretations within the following applications: renewal processes and continuous time random walks; infinite-server queueing systems and shot noise processes; financial derivatives. The interpretation of the Pietra index within the context of financial derivatives implies that derivative markets, in effect, use the Pietra index as their benchmark measure of statistical heterogeneity.     

Has the world economy reached its globalization limit?

The economy globalization measure problem is discussed. Four macroeconomic indices of twenty among the “richest” countries are examined. Four types of “distances” are calculated. Two types of networks are next constructed for each distance measure definition. It is shown that the globalization process can be best characterised by an entropy measure, based on entropy Manhattan distance. It is observed that a globalization maximum was reached during the interval 1970-2000. More recently a deglobalization process has been observed.