Structural and chemical phase transitions in tungsten carbide films evidenced by the analysis of their stiffness tensors

Journal Article · Sun Oct 01 00:00:00 EDT 2006 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2356098· OSTI ID:20884755

Wittkowski, T; Jung, K; Hillebrands, B; Comins, J D ^[1]

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1. Fachbereich Physik und Forschungsschwerpunkt MINAS, Technische Universitaet Kaiserslautern, Erwin Schroedinger-Strasse 56, D-67663 Kaiserlautern (Germany)

Brillouin light scattering (BLS) is used to provide a comprehensive study of thin tungsten carbide films deposited on single crystal silicon substrates whose distinctive nature depends critically on the deposition parameters. The use of stepped films in these slow-on-fast systems provides enhanced data sets and allows the velocity dispersion of the observed surface excitations, including the discrete Rayleigh and Sezawa modes to be studied in detail. Comprehensive and powerful methods of data analysis and interpretation including the recently developed Monte Carlo (MC) method, the surface Green's function, and classical approaches are applied to extract the effective elastic constants and density of each of the films. The MC and Green's function methods are used to remove ambiguities in Sezawa mode assignments and to identify a mode-crossing event. Auger electron spectroscopy and x-ray diffraction investigations confirm conclusions about chemical composition and microstructure obtained by BLS including a structural phase transition, thus leading to a consistent description of elastic, structural, and chemical properties of tungsten carbide films as a function of their deposition conditions. The anisotropic elastic tensors of the various films are employed for an analysis of the angular dependent Young's modulus and the shear modulus, suggesting implications for the film performance in wear protection. Finally, an estimate of the elastic anisotropy of the {alpha}-W{sub 2}C single crystal is provided on the basis of the effective elastic constants of a nanocrystalline W{sub 2}C film.

• OSTI ID: 20884755
• Journal Information: Journal of Applied Physics, Vol. 100, Issue 7; Other Information: DOI: 10.1063/1.2356098; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANISOTROPY
AUGER ELECTRON SPECTROSCOPY
BRILLOUIN EFFECT
CHEMICAL COMPOSITION
CHEMICAL PROPERTIES
CRYSTAL STRUCTURE
DEPOSITION
GREEN FUNCTION
LIGHT SCATTERING
MICROSTRUCTURE
MONOCRYSTALS
MONTE CARLO METHOD
NANOSTRUCTURES
PHASE TRANSFORMATIONS
SILICON
THIN FILMS
TUNGSTEN CARBIDES
WEAR RESISTANCE
X-RAY DIFFRACTION
YOUNG MODULUS