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OTECHNICAL MATERIALS SCIENCE

ZnO Films Obtained by Reactive Magnetron Sputtering: Microstructure, Electrical, and Optical Characteristics V. F. Gremenoka, V. A. Ivanova, A. N. Petlitskiib, T. V. Petlitskayab, S. Kh. Suleymanovc, *, V. G. Dyskinc, M. U. Djanklichc, and N. A. Kulaginac aState

Scientific and Production Association Scientific-Practical Materials Research Centre, National Academy of Sciences of Belarus, Minsk, 220072 Belarus b JSС INTEGRAL, Minsk, 220108 Belarus cInstitute of Materials Science, Scientific Production Association Physics–Sun, Academy of Sciences of Uzbekistan, Tashkent, 100084 Uzbekistan *e-mail: [email protected] Received July 15, 2019; revised November 25, 2019; accepted January 13, 2020

Abstract—In this study, a technology producing undoped crystalline zinc oxide films with purposefully changed electrical resistance ρ = 3 × 10–4–1 × 107 Ω cm has been developed. The relationship between the electrical characteristics of ZnO layers and the parameters of their deposition has been studied, and the conditions for the formation of high-resistance i-ZnO and low-resistance n-ZnO films with specified values of electrical resistance have been determined. It has been established that the dominant factor determining the conductivity of ZnO films is a change in the concentration of free carriers, controlled by oxygen vacancies. To select the optimal conditions for the formation of highly transparent coatings with a given conductivity, the microstructure and spectral properties (edge absorption and transmission spectra in the transparency region) of n-ZnO films deposited by reactive magnetron sputtering of a zinc target in an argon atmosphere with oxygen (10% Ar, 90% O2) at a pressure of 5 × 10–3 Torr have been studied. It has been shown that the developed method for the discrete formation of ZnO films on amorphous substrates provides stoichiometric crystal structures with a high packing density and spatial orientation of crystallites in the [002] direction. Even in the case of n-ZnO films with ρ = 3 × 10–3 Ω cm, the microstructure causes a high transmittance of the coatings. Keywords: zinc oxide (ZnO), reactive magnetron sputtering, crystal structure, electrical and optical characteristics, thin-film solar cells DOI: 10.3103/S0003701X20030044

INTRODUCTION Currently, the development of miniature sources (laser and luminescent), detectors, and radiation converters of the visible wavelength range raise special interest in wide-gap crystalline media with a high concentration of thermo-, photo-, and radiation-stable optically active defects (intrinsic and impurity), providing the possibility of a predictable change in physical (optical, electrical) parameters of the medium, as well as its intense glow at low volumes and low-power pump sources. Deposition and studying the physical properties of zinc oxide films continues to be one of the most important areas of physics of semiconductor materials, which is confirmed by hundreds of scientific articles published annually and numerous conferences