Optical and electrical characterization of CdS thin films

Thin CdS films have been grown by chemical bath (CdCl₂, thiourea, ammonia) deposition (CBD) on SnO₂ (TO)-coated glass substrate for use as window materials in CdS/CdTe solar cells. High-resolution transmission electron microscopy revealed grains with an average size of 10 nm. The structure was predominantly hexagonal with a high density of stacking faults. The film crystallinity improved with annealing in air. Annealing in a CdCl₂ flux increased the grain size considerably and reduced the density of stacking faults. The optical transmission of the as-deposited films indicated a band gap energy of 2.41 eV. Annealing in air reduced the band gap by 0.1 eV. Annealing in CdCl₂ led to a sharper optical absorption edge that remained at 2.41 eV. Similar band gap values were obtained by photocurrent spectroscopy and electroabsorption spectroscopy (EEA) using an electrolyte contact. EEA spectra were broad for the as-deposited and air-annealed samples, but narrower for the CdCl₂-annealed films, reflecting the reduction in stacking fault density. Donor densities of ca. 10¹⁷ cm ^–3 were derived from the film/electrolyte junction capacitance.     

How would an EU-membership of the Visegrád- countries affect Europe‘s economic geography?EU-membership of the Visegrád-countries

The question posed in the title of the paper is answered by simulating EU-integration of the Visegrád-countries by a spatial computable general equilibrium (SCGE) model. A two-sector model is calibrated for a system of almost 100 regions covering the whole area of Europe and a rest of world region. The sectors are a local sector, producing non-tradables under perfect competition, and a tradables sector, producing a large number of tradable varieties under monopolistic competition. Trade between regions is costly, with costs depending on geographic distance and national impediments to trade. The model is calibrated such that the equilibrium solution reproduces benchmark data about international trade and regional incomes. Economic integration is simulated by reducing impediments to trade between integrating countries and calculating a new counterfactual equilibrium.     

Atomic force microscopy on polymers and polymer related compounds

Summary Surface morphology and molecular arrangement have been recorded by atomic force microscopy (AFM) on polytetrafluoroethylene (PTFE) and on polycarbonate (PC) films. In a thin layer of PTFE deposited by rubbing polymer on hot glass substrate unidirectional orientation of polymer has been revealed. Individual polymer chains have been visualized. An interchain distance of .53 nm and several periodicities along the chain contours have been found-.44 nm, .62 nm and .82 nm-in accordance with a 13/6 helix.The monitoring of surface changes during thermal treatment of amorphous-bis-phenol A-PC film has been realized by AFM. Different types of surface morphology were revealed. Spherulites are formed during polymer crystallization. In most cases, however, numerous nanocrystallites appeared after thermal treatment. On their surfaces well-ordered atomic scale AFM images have been received. The arrangement of AFM patterns can be characterized by periodicities of .50 nm and .52 nm in the orthogonal directions. Polycarbonate oligomers-as the product of surface degradation-effectively might form the observed nanocrystallites.Prof. Dr. G. Zachmann zum 60. Geburtstag herzlichst gewidmetThese results were given by us first in a lecture in Baltimore, at the 5th ISPAC Symposium on May 31, 1991, and in a lecture in Santa Barbara, at the Nanoscope Users Meeting on June 25, 1991     

Zur Reaktivität von Tanninen in Abhängigkeit vom Kambialalter

Ohne Zusammenfassung     

Ionic conductivity in dehydrated zeolites

The ionic conductivity of pressed pellets of dehydrated synthetic offretite, cancrinite and zeolite A, with various alkali metal ions, was determined by low-frequency impedance spectroscopy. Experiments were carried out in the frequency range 10 Hz–10 MHz at temperatures from 100–600°C. The conduction activation energies range between 55 kJ mol^?1 (Na-zeolite A) and 108 kJ mol^?1 (Li-cancrinite). The best conductivity value obtained was that of Na-zeolite A with 2.9×10^?3Ω^?1cm^?1 at 600°C.     

High‐error approximate dictionary search using estimate hash comparisons

A method for finding all matches in a pre‐processed dictionary for a query string q and with at most k differences is presented. A very fast constant‐time estimate using hashes is presented. A tree structure is used to minimize the number of estimates made. Practical tests are performed, showing that the estimate can filter out 99% of the full comparisons for 40% error rates and dictionaries of up to four million words. The tree is found to be efficient up to a 50% error rate. Copyright © 2006 John Wiley & Sons, Ltd.