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14.7: Summary

  • Page ID
    36488
  • Thin films can be constructed by the deposition of vapourised atoms onto a substrate surface. There are 2 principle methods of generating the flux for Physical Vapour Deposition (PVD) – Evaporation and Sputtering. Both of these involve the use of a vacuum chamber.

    Evaporation
    • Thermal Process
    • High Vacuum
    • Low energy vapour flux
    • Line of sight deposition

    Sputtering

    • Physical Process
    • Background of Inert Gas
    • High energy vapour flux
    • Scattering of atoms

    If the incoming vapour flux has low energy, then the resultant film will have shadowed regions. However, if there is enough energy for surface diffusion to occur then the film will rearrange into one of 3 possible structures – depending on the relative bonding energies between the film and substrate atoms.

    Deposition of films made from alloys or compounds are more difficult, as the different elements will not necessarily react to the environment in the same way. One way around this issue is a process known as Pulsed Laser Deposition (PLD). This involves heating the source material instantaneously using a focussed laser in order to avoid fractioning.

    Going further

    Books

    M. Ohring, The Materials Science of Thin Films, Academic Press, 1992, ISBN: 0-12-524990-X

    Websites

    Other resources

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