Electrical conductivity of thin films grown by deposition of random clusters of particles
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Electrical conductivity of thin films grown by deposition of random clusters of particles Zhaleh Ebrahiminejad1, Hossein Hamzehpour2,3,*
, and S. Farhad Masoudi2
1
Department of Physics, West Tehran Branch, Islamic Azad University, Tehran, Iran Department of Physics, K.N. Toosi University of Technology, Tehran 15875-4416, Iran 3 School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran 2
Received: 13 June 2020
ABSTRACT
Accepted: 28 August 2020
Extensive numerical simulation of the frequency-dependent effective conductivity of porous thin films, grown by deposition of clusters of elementary particles with various shapes and sizes, as well as rodlike particles has been analyzed and reported. The dependence of frequency-dependent effective conductivity re ðsÞ of films on their morphology has been studied. The conductivity variations versus the size of deposited clusters have been investigated which show a decreasing function behavior. Also, the conductivity depends on the frequency s by a power law whose exponent is non-universal, but depends weakly on the size of the clusters. The non-universality of the exponent is in agreement with the experimental data for the electrical conductivity of a wide variety of materials. In order to study the important characteristic of well-connected materials, the direct current conductivity as a function of films’ stationary porosity has been investigated which shows an essentially linear function. It also grows as a power law with the thickness of the film, which is also in agreement with the past experimental data.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Heterogeneous solid films (SFs) have wide applications, ranging from low-dielectric constant composites, to optical coatings, sensors, and insulating materials [1, 2]. The SFs with specific electronic, optical, and mechanical properties have been studied for a long time because of their important applications, fabrication, and characterization [3]. They are usually grown by molecular-beam epitaxy (MBE) or
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https://doi.org/10.1007/s10854-020-04378-4
by chemical vapor deposition [4, 5]. These and other methods involve a variety of complex phenomena that grow the films on the two-dimensional (2D) initially flat substrates [6]. Such phenomena include nucleation, aggregation, and coalescence of islands on the surface. In the MBE method, for example, particles are deposited on a substrate by a directed beam then they reach energetically favorable positions with diffusing on the substrate and they stick to the surface of the growing film [4, 5]. In the
J Mater Sci: Mater Electron
submonolayer and early multilayer growth, distribution of various sizes islands is formed. The morphology of which depends on the microscopic details of the fabrication process, including the deposition rate, temperature, the strength of surface diffusion, and the structure of the substrate’s surface. It is cle
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