A Study of Microwave Radiation Absorption in Ultrathin Conducting Films
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ICAL ELECTRONICS
A Study of Microwave Radiation Absorption in Ultrathin Conducting Films V. V. Starostenkoa, V. B. Orlensona, A. S. Mazinova,*, and I. Sh. Fitaeva a
Crimean Federal University, Simferopol, 295007 Russia *e-mail: [email protected]
Received November 22, 2019; revised February 3, 2020; accepted March 20, 2020
Abstract—The interaction between microwave electromagnetic waves and conducting films with a nanometer thickness in the homogeneous region approximation and a structure consisting of micro- and nanoparticles has been numerically simulated. Using rigorous coupled-wave analysis, the dynamics of the changes in the optical coefficients from the values characteristic of a dielectric to the values for a homogeneous conducting film has been investigated and the effect of the size and distribution of conducting islands on the electrodynamic characteristics has been analyzed. DOI: 10.1134/S1063784220080186
INTRODUCTION Conducting films are objects of interest in semiconductor electronics, optics, shielding products and radioengineering devices from external electromagnetic fields, and other fields of science and engineering. They are widely used in electromagnetic absorbers and solar energy storage systems [1, 2]. The properties of conducting films significantly depend on different parameters, in particular, thickness, which determines a mechanism of conversion of the electromagnetic field energy (EMF) into heat energy. The physical processes in nanometer-thick conducting films are inextricably linked with the characteristics of substrates, which form a metal–dielectric structure (MDS) with them. A film with a thickness of smaller than 10 nm is not continuous, but represents a set of conducting islands (nanoparticles), i.e., scattering centers [3]. The physical and electrodynamic properties of the films strongly change after passing through this conditional boundary. For conducting films on low-cost amorphous substrates (borosilicate glass, sitall, glass, polymer films, etc.) with a roughness of lower than 10 nm, the concepts of thickness and conductivity are fairly conventional. As a rule, films with a thickness of smaller than 10 nm are put in correspondence with the deposition time. In a film with a unit surface and thickness d, the resistance Rs = 1/σd(Ω) changes its physical properties from dielectric (σ = 0) to well-conducting, which shorts out the space almost completely reflecting the incident wave [4]. In the thickness range of 2–10 nm, the maximum EMF energy absorption lies in the radiofrequency region. In studying and analyzing the optical coefficients of nanometer films [5], the concepts of
characteristic resistances and the transmission line apparatus were used, ignoring the possibility of transformation of a plane wave into waves of other types and the spatial and ohmic inhomogeneity of the films, i.e., real physical characteristics of substrates and films. The results of investigations of the diffraction properties of MDSs were reported, to different extents, in [6–12]. To examine the pr
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