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Paper   IPM / Physic / 14171
School of Physics
  Title:   Electrical conductivity of the films grown by ballistic deposition of rodlike particles
1.  E. Sharafedini
2.  H. Hamzehpour
3.  S.F. Masoudi
4.  M. Sahimi
  Status:   Published
  Journal: J. Appl. Phys.
  Vol.:  118
  Year:  2015
  Pages:   215302
  Supported by:  IPM
Using extensive Monte Carlo simulations, we study the growth of films by ballistic deposition of rodlike particles with various sizes on a one-dimensional substrate. Particles are deposited over an initially flat substrate, which leads to the formation of a porous film with rough surface. The surface width and the corresponding scaling exponents α and β and, hence, the dynamic exponent z are calculated. Also studied is the time evolution of the porosity of the material and its dependence on the particles' size. The frequency-dependent electrical conductivity of the film and its dependence on the size of the particles and the porosity are also studied. The morphology of the films, as characterized by its surface width, follows three types of evolution before reaching its ultimate structure. At short times, film growth is close to the random deposition model with the growth exponent β1 ≈ 1/2. At intermediate times, the surface width grows more slowly with a growth exponent of β2 ≈ 1/3. Finally, at long times, the width saturates and is characterized by a roughness exponent α ≈ 1/2. The results also indicate that even if the film is grown with particles of various sizes, the universality class of the model remains unchanged. The films' porosity grows rapidly with the time, before eventually saturating. As the size of the particles increases, the saturation porosity ultimately attains a value of ϕs=0.5. The frequency-dependent effective conductivity σe is a decreasing function of the deposited particles' size, as well as the porosity. The dc conductivity depends on the particle size through a power law. As is the case with a wide variety of disordered materials, the effective conductivity depends on the frequency through a power law.

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