Publication: Co-deposited Si-Al thin films as a base material to decrease the reflectance in the millimeter-band frequencies
Дата
2022
Авторы
Kartashova, A. M.
Volkovoynova, L. D.
Serdobintsev, A. A.
Kozhevnikov, I. O.
Kozyrev, A. A.
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© 2022 SPIE.Ongoing active development of modern radiofrequency electronic devices operating in the millimeter (V) band, such as 5th-generation wireless communications demands new materials to control electromagnetic interference, compatibility and reliability of such systems. Here we present a follow-up of studies on antireflective and absorptive micrometer-thick film coatings for operation in V-band using simultaneous magnetron co-deposition of silicon and aluminum. In this system graded segregation was observed under certain regimes, resulting in a depth gradient of aluminum content. Further investigations on the morphology of the obtained films were performed. Inhibition of electromagnetic waves reflection in 50-70 GHz range by up to 27 dB (at least 10 dB throughout the whole range) was achieved through variation of Al content in coatings by the ratio of sputtered atoms fluxes. Surface morphology of films as well as optical properties of those in visible and near IR bands were investigated. It was found that electrophysical properties of resulting samples are severely influenced by the amount and homogeneity of aluminum distribution in the coating. Optical spectroscopy suggests that variation of aluminum content in the film allows for control over resulting film material kind that can be adjusted from dielectric through semiconductive to almost metal-like. Non-homogeneous aluminum distribution in the depth of the film, particularly existence of a two-layered semiconductive optical structure in samples prepared at particular deposition regime was confirmed by measuring optical reflection spectra from the coating side and in reverse. Segregation of aluminum towards the surface of the film in course of silicon recrystallization was confirmed by AFM and surface roughness measurements.
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Co-deposited Si-Al thin films as a base material to decrease the reflectance in the millimeter-band frequencies / Kartashova, A.M. [et al.] // Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - 2022. - 12193. - 10.1117/12.2626493