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  • 1
    Electronic Resource
    Electronic Resource
    Backscattering Factor for KLL Auger Yield from Film-Substrate Systems (1996)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 24 (1996), S. 15-22 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Backscattering factor (R) between primary energies of 2-40 keV for film-substrate KLL Auger backscattering yield (RFS) is calculated via Monte Carlo simulation for C and Al films. Substrates ranging from Be (Z=4.0) to Au (Z=79.0) are used in the study. Results via a normalizedRFS (RN) function show that substrate effects are indeed present. This is especially so at higher primary energies and lower film atomic number. Electron range results also show that an important and meaningful quantity to describe the backscattering Auger yield with respect to film thickness is the mean backscattered energy penetration depth. This is found to be essentially different from the half-maximum electron range as proposed earlier. A power law can be used to describe the half-value range (i.e. the thickness for whichRN=0.5) with respect to primary energy. For Al film, however, a discontinuity in the power law is found for energies 〈4 keV. This is attributed mainly to the relatively large binding energy of the Al K-shell and also to the greater variation of the K-shell cross-section within the backscattered energy spectrum. A new analytical interpolation formula is proposed to calculateRFS. This model accounts for substrate effects at only primary energies 〉4 keV. At lower energies mean values are used instead. Besides the fitted parameters from our results, known bulkR expressions for film and substrate are also required for the practical use of the model.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Bethe ionization cross-sections: A quantitative survey on calculating the backscattering factor in AES (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 19 (1992), S. 227-231 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The objective of this work is to investigate the usefulness of the Bethe cross-section with Powell parameters for possible future use in quantitative AES. The Powell energy-dependent parameters are obtained from a least-squares fit to various experimental and calculated work on ionization cross-sections and are proven to have an accuracy of better than about 1% for Unl 〉 4 (Unl = E0/Enl), where E0 is the incident electron energy and Enl is the binding energy of the electrons in the nl-shell. This cross-section was quantum mechanically derived from the first Born approximation by Bethe and its use can be extended to lower-energy ranges as evidenced from the Fano plots available. This means that the cross-section has the advantages of a closer fit to experimental data and is within the energy range of interest in AES. A simple Monte Carlo approach has been adopted to calculate the backscattering factor and related Auger intensity lines using this cross-section for C, Si, Cu and Ag elements. Results compared with both recent experimental data and Gryzinski cross-section results indicate strongly that the Bethe cross-section can be used for future quantitative analysis in AES.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740190144
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Present limits to the calculation of auger line intensities for film-substrate systems (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 21 (1994), S. 199-205 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new and simple algebraic expression for calculation of backscattering factors in the film-substrate systems has recently been proposed. The limits of its use with the Gryzinski ionization cross-section to calculate Auger line intensities were, however, not throughly discussed. We have examined more closely its range of validity using Monte Carlo simulation and recent experimental data available. Film-substrate systems of carbon films on Cu, Sn and Ta substrates and Cu films on C, Sn and Ta substrates were investigated. Our results have indeed shown that there are disagreements. Contributing factors to some of the disagreements include the proposed backscattering factor expression and the ionization cross-section used. New proposals for quantification were suggested using an alternative interpolation factor taking into account substrate scattering behavior and the Bethe ionization cross-section. Results of the new proposals did show significant improvements with the use of the Bethe ionization cross-section for the case of carbon film-substrate systems. Results for Cu film-substrates were not conclusive, with only one evident improvement for Cu/C using the Bethe cross-section.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740210306
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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