Characterization Of Film-substrate Interface Structure And Its Energy Calculation

For thin polycrystalline films, especially those with columnar structure, once the diameter of grains on the film surface is larger than the film thickness, the total area of above (free surface) and under basal planes (film-substrate interface) will be larger than that of side plane. Therefore besides the minimization of boundary energy in traditional bulk material, surface energy, interface energy would be considered due to the anisotropy of surface energy, interface energy being able to drive the grain growth and texture evolution in thin films. The structure and energy of film-substrate interface affect not only its combinative strength but also the capability of the film.In this paper we have characterized the structure of various twist interfaces which are composed of (001 ),(011),(111 )-oriented semi-infinite crystals of four face-centered cubic (FCC) metals Ag, Au, Al, Cu and (001), (lll)-oriented semi-infinite crystals of Si respectively with the coincidence site lattice, and calculated their energy with Modified Embedded Atom Method (MEAM).Firstly, using compiled programs in Matlab, the related parameters of twist interfaces composed of (001), (011), (lll)-oriented semi-infinite crystals of four face-centered cubic (FCC) metals Ag, Au, Al, Cu and (001), (11 l)-oriented semi-infinite crystals of Si respectively have been determined including twist angleθ, ratio of the inverse planar coincident-site densities ∑_M^· /∑_Si^·,, the elements of translation matricesU₁(=UM)and U2(=USl)uyk (i,j=1, 2) and misfit degrees F₁ (i=l,2).With Modified Embedded Atom Method (MEAM) we have calculated these interface energies too. Following results have been obtained.(1) Different from energy of grain boundary, the interface energies are not zero at twist angle 9 = 0° for interfaces composed of two different semi-infinite crystals with same orientation.(2) For those interfaces, there is a position d0 + â–³de (where is its increment) at which the interface energies arelowest between two crystals, and this position does not relate .o twist angle. Also, â–³de and average values of energy for each twist interface E almost decrease with...