Optical Properties of Nonstoichiometric Tantalum Oxide TaOx (x < 5/2) According to Spectral-Ellipsometry and Raman-Scattering Data


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Abstract

Optical properties of amorphous nonstoichiometric tantalum-oxide films of variable composition (TaOx, x = 1.94–2.51) in the spectral range of 1.12–4.96 eV, obtained by ion-beam sputtering-deposition of metallic tantalum at different partial oxygen pressures (0.53–9.09 × 10–3 Pa), have been investigated. It is shown by spectral ellipsometry that the character of dispersion of the absorption coefficient and refractive index in TaOx of variable composition suggests that light-absorbing films with dispersion similar to that in metals are formed at oxygen pressures in the growth chamber below 2.21 × 10–3 Pa, whereas transparent films with dielectric dispersion are formed at pressures above 2.81 × 10–3 Pa. According to the data of quantumchemical simulation, the absorption peak at a photon energy of 4.6 eV in TaOx observed in the absorptioncoefficient dispersion spectrum is due to oxygen vacancy. The peak in the Raman-scattering spectra of TaOx films with metallic dispersion at frequencies of 200–230 cm–1 is presumably related to tantalum nanoclusters.

About the authors

V. N. Kruchinin

Rzhanov Institute of Semiconductor Physics, Siberian Branch

Author for correspondence.
Email: kruch@isp.nsc.ru
Russian Federation, Novosibirsk, 630090

V. A. Volodin

Rzhanov Institute of Semiconductor Physics, Siberian Branch; Novosibirsk State University

Email: kruch@isp.nsc.ru
Russian Federation, Novosibirsk, 630090; Novosibirsk, 630090

T. V. Perevalov

Rzhanov Institute of Semiconductor Physics, Siberian Branch; Novosibirsk State University

Email: kruch@isp.nsc.ru
Russian Federation, Novosibirsk, 630090; Novosibirsk, 630090

A. K. Gerasimova

Rzhanov Institute of Semiconductor Physics, Siberian Branch

Email: kruch@isp.nsc.ru
Russian Federation, Novosibirsk, 630090

V. Sh. Aliev

Rzhanov Institute of Semiconductor Physics, Siberian Branch

Email: kruch@isp.nsc.ru
Russian Federation, Novosibirsk, 630090

V. A. Gritsenko

Rzhanov Institute of Semiconductor Physics, Siberian Branch; Novosibirsk State University; Novosibirsk State Technical University

Email: kruch@isp.nsc.ru
Russian Federation, Novosibirsk, 630090; Novosibirsk, 630090; Novosibirsk, 630073

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