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  • 1
    Electronic Resource
    Electronic Resource
    Determination of metal-cofactors in respiratory chain complexes by total-reflection X-ray fluorescence spectrometry (TXRF) (1998)
    Springer
    Fresenius' journal of analytical chemistry 361 (1998), S. 326-328 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Total Reflection X-Ray Fluorescence Spectrometry (TXRF) offers many advantages for the detection of trace elements in enzymes as compared to other well known analytical techniques like flame-AAS or ICP-AES because of the significantly smaller amounts of sample required. Without any decomposition, elements like Fe, Ni, Cu, Zn, Mn and Mo could be determined with high accuracy, in spite of the large bio-organic matrix. Besides the metals also sulfur can be determined in protein samples. The two terminal oxidases, cytochrome c oxidase and quinol oxidase, isolated from the soil bacterium Paracoccus denitrificans, were transferred from their usual salt buffer into a solution of 100 mmol/L tris(hydroxymethyl)aminomethane (TRIS) acetate containing an appropriate detergent. By this procedure an improved signal/noise ratio is attained. The data for cytochrome c oxidase are in good agreement with values obtained by ICP-AES. Further results of quinol oxidase, which has different element ratios, also fit the expected values. The investigations lead to the conclusion that the method is well suited for the quantitative determination of metals in enzymes, and in particular their molar ratios, and requires only small amounts of the biological sample without any extensive pretreatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050895
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of transition metal nitride formation in rapid thermal processing (RTP) (1999)
    Springer
    Fresenius' journal of analytical chemistry 365 (1999), S. 199-202 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The potential of RTP for the preparation of transition metal nitrides by reaction of metal thin films in molecular nitrogen was investigated. The films and the nitridation process were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive x-ray analysis (EDX) in a scanning electron microscope (SEM) and secondary neutral mass spectrometry (SNMS). The chemical states of vanadium at the utmost surface, detected by XPS, are related to V2O5 before RTP and to vanadium nitride, oxide and oxynitride after RTP. The deposition of a 3 nm Si top layer prevents V from oxidation and its selective removal before RTP enhances the proportion of nitride determined by XPS after RTP. From comparative experiments in a conventional tube furnace the advantages of RTP became obvious. With short process times of the RTP technique the integral amount of residual oxygen is kept low and oxide formation is largely avoided. The nitrogen content and the different polycrystalline phases formed by varying process time and temperature provide information about reactivity and the nitridation process. The nitrogen to vanadium ratio was determined by EDX and SNMS, revealing that the N content reaches saturation after only 5 seconds at 1100 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051472
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of crystal faces of polycrystalline HFCVD diamond films by STM/STS (1997)
    Springer
    Fresenius' journal of analytical chemistry 358 (1997), S. 335-338 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Among the numerous techniques available for the characterization of diamond films scanning tunnelling microscopy (STM) in combination with spectroscopy (STS) provides information about the morphology and electronic surface properties down to the atomic scale. Here results of STM/STS obtained on diamond films are reported. 0.5 to 1.25 μm thick films have been grown on silicon substrates by hot filament chemical vapour deposition (HFCVD) by variable CH4/H2 mixtures in the range of 0.5% to 3% CH4. Morphological features of diamond crystallites were studied in detail by STM. A distinct increase of the surface roughness of (111) crystal faces with increasing CH4 concentration (from 0.5% to 3%) was found. For a CH4 concentration of 3% (100) faces were smoother than (111) faces. STS revealed significant differences in the tunneling current/voltage (I/V)-characteristics between (111) and (100) crystal surfaces. For (111) surfaces distinct changes in the I/V-characteristics depending on the CH4 concentration were observed: The I/V-characteristics change and the conductivity increases raising the CH4 concentration from 0.5% to 3%. This effect is explained with increasing formation of non-diamond carbon (NDC) on (111) surfaces for higher CH4 concentrations. Thus NDC is also responsible for the enhanced surface roughness observed on (111) surfaces with increasing CH4 concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050422
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  • 4
    Electronic Resource
    Electronic Resource
    Formation and nature of swirl defects in silicon (1975)
    Springer
    Applied physics 8 (1975), S. 319-331 
    Details
    ISSN: 1432-0630
    Keywords: Self-interstitials in silicon ; Swirls ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Point defect agglomerates in dislocation-free silicon crystals, usually called “swirls”, have been investigated by means of high-voltage electron microscopy. It was found that a single swirl defect consists of a dislocation loop or a cluster of dislocation loops. By contrast experiments it could be shown that these loops are formed by agglomeration of self-interstitial atoms. Generally the loops have a/2〈110〉 Burgers vectors, but in specimens with high concentrations of carbon (∼1017 cm−3) and oxygen (∼1016 cm−3) also dislocation loops including a stacking fault were observed. In crystals grown at growth rates higher thanv=4 mm/min no swirls are observed; lower growth rates do not markedly affect the size and shape of the dislocation loops. With decreasing impurity content (particulary of oxygen and carbon) the swirl density decreases, whereas the dislocation loop clusters become larger and more complex. A model is presented which describes the formation of swirls in terms of agglomeration of silicon self-interstitials and impurity atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00898366
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  • 5
    Electronic Resource
    Electronic Resource
    Surface and thin film analysis in silicon technology: actual and future problems and demands (1989)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 333 (1989), S. 561-568 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to aim at production yields at economical levels in VLSI (verylargescaleintegration) technology a high degree of process maturity and stability has to be achieved. This requires a comprehensive characterization and control of the materials and processes used, and henceforth, the availability of appropriate analytical methods and tools. Thereby surface and thin film analytical tools play a key role and have to be applied from the very beginning of the development of a device technology. In the course of the full fabrication process a large number of thin films of inorganic (e.g., metals, insulators) and organic (e.g., photoresists) material is deposited, etched and completely or locally removed. The properties and quality of those thin films and the many surfaces and interfaces formed or occurring prior to and after the various processes such as film deposition, wet and dry etching, cleaning and the like have to be characterized and controlled. For the manifold surface analytical tasks nowadays a large number of techniques is available: Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), Rutherford backscattering (RBS), total reflexion X-ray fluorescence analysis (TRXFA), plasma chromatography mass spectrometry (PCMS). Here examples are discussed where those methods are applied to problems arising in the process development as well as failure analysis of advanced circuits, in particular a 4 M DRAM (megabitdynamicrandomaccessmemory). Finally, limitations of the available methods and future problems and demands are pointed out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00572377
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    Paper (German National Licenses)
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