Manfred Grasserbauer

Influences of WC-Co hard metal substrate pre-treatments with boron and silicon on low pressure diamond deposition

Abstract Diamond coatings were produced on WC-Co hard metal substrates. To improve the adhesion between the diamond coating and the substrate a substrate surface pre-treatment with boron or with silicon vapor was applied. This surface pre-treatment resulted in an increase in both the diamond nucleation density and the diamond growth rate. Simple adhesion tests confirmed an improved adhesion of thin diamond layers as compared with those on untreated hard metal substrates. Secondary ion mass spectroscopy (SIMS) depth profiles revealed an enrichment of B or of Si at the substrate-diamond interface due to the pre-treatment procedure. The correlation of the Co and W depth profiles in samples coated for 12 and 24 h supports the theory of diamond dissolution into the substrate. Co was detected only in the interface regions and on the surface of the diamond layers but not in the bulk of the thick layers. The SIMS results confirm X-ray examinations of the hard metal Co binder phase.

The surface morphology of ion-selective membrane electrodes: Part 2. Studies on the Copper(II)-selective Electrode

Abstract The response of copper(II)-selective electrodes based on copper(II) sulphide incorporated in silicone rubber or compressed to pellets is described, with particular reference to electrode behaviour after treatment with various oxidizing agents and regeneration by chemical procedures. Changes in the surface state of the membranes were examined by electron microprobe analysis and photoelectron spectroscopy. The electrochemical behaviour of the membranes can be correlated with surface morphology changes, primarily connected with formation of sulphate monolayers.

Neural networks for library search of ultraviolet spectra

Abstract An artificial neural network is used to implement a spectral library search system for UV spectra obtained from a diode-array detector after liquid chromatographic separation. The net is trained by a slightly modified backpropagation algorithm. Several parameters were optimized to ensure convergence and to speed up learning. Sets of up to 200 UV spectra can successfully be learned by a neural network. The neural net is not able to classify unknown spectra as unknown. This is due to the feedforward algorithm used. On the other hand in the case of noisy spectra a well trained net can produce results superior to classical methods of library search like the correlation coefficient. The crucial point is the selection of the appropriate training data set. To facilitate a correct identification the training data have to include the full dynamic range of noise. Extrapolation beyond the training data space is not recommended since the results are not reliable. In the case of impurities the net is better than the correlation coefficient, although the training data consisted only of pure spectra. If one is aware of the limitations neural networks are a powerful tool for a robust identification of UV spectra.

Three dimensional ultra trace analysis of materials

We have developed a new imaging system for secondary ion mass spectrometry, including a new interface to control all functional units of the CAMECA IMS 3f instrument, especially the high voltage channel plate. Use of a 386 PC (HP Vectra RS-25) made a new 20-bit magnetic field control, a new counting board with higher dynamic range and a new sample position unit possible. A double channel plate enables us to detect single ions with a sensitive CCD camera.An Imaging Technology 151 image processor digitizes and accumulates camera data. During summation the image processor detects the brightest and darkest pixel in the channel plate picture, thus channel plate high voltage may be dynamically controlled according to the intensity of the secondary ion signal. This results in fully automatic measurement of unknown samples with large variations in the lateral and depth concentration of elements. A dynamic range for measurement of secondary ion intensities of 108 can be achieved.Software written in C controls the image processor, the channel plate high voltage and all other parts of the instrument, and has a user friendly interactive interface. To visualise multidimensional data (three dimensional distribution of more than one element) a software package was written which allows to correlate elemental distributions.

Ultra trace analysis of refractory metals by solid state mass spectrometry — A comparison of GDMS, SSMS and SIMS

The approach to evaluate the analytical figures of merit of GDMS, SSMS and high performance SIMS for ultra trace analysis in refractory metals by comparative analysis of the same material is described. The major features of the individual techniques are discussed and the results obtained with GDMS, SIMS, SSMS (supplemented by some NAA data) on sintered tungsten and molybdenum samples compared.

High performance analytical characterization of refractory metals

It is first shown what effects trace impurities generally exert on metal properties and why trace analysis is essential to modern applications of refractory metals in todays high technology. The effect of trace impurities in metals on complex systems like microelectronic components is also discussed.It is then shown, what principal analytical requirements are mandatory for trace characterization of refractory metals at levels of rising purity (4 N to 6 N). A survey of analytical methods for trace and ultratrace characterization of refractory metals is given including the following methods: flame and graphite furnace atomic absorption spectrometry, ICP and DCP-atomic emission spectrometry, X-ray fluorescence spectrometry, activation analysis, mass spectrometric methods, especially SIMS and GDMS.

Characterization of thin-film electroluminescent structures by SIMS and other analytical techniques

ZusammenfassungNeuentwickelte epitaktische Abscheideverfahren („Atomic Layer Epitaxy — ALE“) ermöglichen die Herstellung von elektroluminescierenden Dünnfilmstrukturen hoher Qualität, welche für verschiedene elektronische Displays eingesetzt werden können. Neben der lichtemittierenden Schicht — üblicherweise Mangan-dotiertes ZnS — enthalten derartige Strukturen einige andere Komponenten wie Al2O3- oder Indium-Zinn-Oxid-(ITO)-Schichten. Die Gesamtdicke aller Schichten eines Displays beträgt ca. 2 μm. Für die Bestimmung der Aktivatorkonzentration (Mn) sowie von Terbium und der Schichtdicke von ZnS wurde eine röntgenfluorescenzanalytische Routinemethode ausgearbeitet. Die Sekundär-Ionen-Massenspektrometrie (SIMS) ermöglicht die Charakterisierung der Schichtstrukturen und der Verunreinigungen in einzelnen Schichten. Dies gestattet insbesondere die Untersuchung der Verteilung und Diffusion des wichtigen Spurenelementes Natrium.SummaryThe recently developed Atomic Layer Epitaxy (ALE) method produces good quality electroluminescent thin-film structures which can be used in various display applications. Besides the light emitting layer which is usually ZnS: Mn2+, the structures contain several other components such as aluminium oxide and indium-tin oxide layers; the total thickness is around 2 μm. It was found that XRF provides a convenient way for the determination of activator concentrations and film thicknesses while SIMS can be used for the determination of depth profiles in a wide concentration range. A rapid and accurate method for the routine determination of Mn2+ and Tb3+ in ZnS by XRF is described and the use of SIMS for the study of sodium distribution and diffusion is discussed.

The surface morphology of ion-selective membrane electrodes : Part I. Studies on silver iodide-based silicone rubber membrane electrodes

Abstract Electron micrographs, and micrographs of electron absorption and silver and iodine distribution on the surfaces and cross-sections of silver iodide-based silicone-rubber membranes showing Nernstian electrode response are presented. An electron microprobe analyzer was used. The electrochemical effects of concentrated (0.6 M) potassium iodide solutions and iron(III) hydroxide or iron(III) ions, are described. The phenomena are interpreted on the basis of the results obtained by electrochemical, atomic absorption and electron microprobe analysis.

Multielement ultratrace analysis of molybdenum with high performance secondary ion mass spectrometry

Electron beam melting has been used to obtain ultrapure refractory metals that are gaining importance in metal oxide semiconductor--very large scale integration (MOS--VLSI) processing technology, fusion reactor technology, or as superconducting materials. Although the technology of electron beam melting is well established in the field of production of very clean refractory metals, little is known about the limitations of the method because the impurity level of the final products is frequently below the detection power of common methods for trace analysis. Characterization of these materials can be accomplished primarily by in situ methods like neutron activation analysis and mass spectrometric methods (glow discharge mass spectrometry (GDMS), secondary ion mass spectrometry (SIMS)). A suitable method for quantitative multielement ultratrace bulk analysis of molybdenum with SIMS has been developed. Detection limits of the analyzed elements from 10/sup -7/ g/g down to 10/sup -12/ g/g have been found. Additional information about the distribution of the trace elements has been accumulated.

Influence of boron on diamond growth on WC-Co hardmetals

Abstract Diamond coatings were produced by the hot-filament method, adding B(C2H5)3 to the gas phase. We compared the results on WC-Co hardmetal and Si substrates. SIMS-measurements revealed high B contents in diamond layers on WC-Co substrates accompanied by high amounts of Co. TEM showed CoB and CO2B inclusions in the diamond layer. Furthermore, B-diffusion in the WC-Co bulk was shown. On Si substrates, crystal quality and growth rate decreased at high B concentrations. Higher B contents were found in the diamond layer than were used in the gas phase.