coatings Article Providing a Speciﬁed Level of Electromagnetic Shielding with Nickel Thin Films Formed by DC Magnetron Sputtering Oleg A. Testov 1 , Andrey E. Komlev 2 , Kamil G. Gareev 1,3, * , Ivan K. Khmelnitskiy 1,3 , Victor V. Luchinin 1,3 , Eugeniy N. Sevost’yanov 1 and Igor O. Testov 1,3   Citation: Testov, O.A.; Komlev, A.E.; Gareev, K.G.; Khmelnitskiy, I.K.; Luchinin, V.V.; Sevost’yanov, E.N.; Testov, I.O. Providing a Speciﬁed Level of Electromagnetic Shielding with Nickel Thin Films Formed by DC Magnetron Sputtering. Coatings 2021, 11, 1455. https://doi.org/ 10.3390/coatings11121455 Academic Editor: Susana Sério Received: 4 October 2021 Accepted: 25 November 2021 Published: 26 November 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional afﬁl- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Engineering Centre for Microtechnology and Diagnostics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; otestov@mail.ru (O.A.T.); khmelnitskiy@gmail.com (I.K.K.); cmid_leti@mail.ru (V.V.L.); sevostyanov86@bk.ru (E.N.S.); igortestov1999@mail.ru (I.O.T.) 2 Department of Physical Electronics and Technology, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; aekomlev@etu.ru 3 Department of Micro and Nanoelectronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia * Correspondence: kggareev@etu.ru Abstract: Nickel ﬁlms of 4–250 nm thickness were produced by DC magnetron sputtering onto glass and silicon substrates. The electrical properties of the ﬁlms were investigated by the four-probe method and the surface morphology of the ﬁlms was studied by atomic force microscopy. To measure the shielding effectiveness, a portable closed stand based on horn antennas was used. A theoretical assessment of the shielding effectiveness of nickel ﬁlms of various thickness under electromagnetic radiation of a range of frequencies was carried out using two different approximations. The results demonstrate the shielding effectiveness of up to 35 dB of the nickel thin ﬁlms in the frequency range of 2–18 GHz. Keywords: nickel; electromagnetic shielding; metal thin ﬁlms; vacuum deposition; DC magnetron sputtering; electrical resistivity; atomic force microscopy; theoretical calculation 1. Introduction The widespread use of devices generating electromagnetic radiation (EMR) requires operative decisions focused on eliminating related technical problems. First of all, these are the problems of electromagnetic compatibility of various electrical appliances and their protection from an external electromagnetic inﬂuence [1]. The main source of electromag- netic waves (EMW) are electronic devices operating in the decimeter (ultra high frequency, 0.3–3.0 GHz) and centimeter (super high frequency, 3–30 GHz) wavelength ranges. There is a trend of increasing operating frequencies of EMW, which aims at increasing the data transfer rate. The traditional way of preventing the EMW pollution is the use of electromagnetic shields based on high-conductivity metals [2,3], composite materials with conductive [4,5] or magnetic ﬁllers [6,7], conductive polymers [5,8] and other materials [9–11] forming a protective shell. The priority task at the stage of developing an electromagnetic shield is to maximize the value of shielding effectiveness (SE). It is necessary to take into account additional requirements for the shield operational characteristics, such as weight, dimensions and temperature range of operation. Most of the recent solutions in the design of electro- magnetic shields are based on high-conductivity metals with the electrical resistivity of ρ v < 10.0 μΩ·cm at room temperature [12–14]. In addition to high conductivity, a metal coating must have corrosion resistance, high adhesion and minimal internal mechanical stress. The corrosion resistance depends on the properties of the oxide ﬁlm formed on the metal surface. The protective effect of the Coatings 2021, 11, 1455. https://doi.org/10.3390/coatings11121455 https://www.mdpi.com/journal/coatings