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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 17:59 |
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Conference: Bucharest University Faculty of Physics 2017 Meeting
Section: Optics, Spectroscopy, Plasma and Lasers
Title:
Preliminary studies on process characterization for tailoring the optical properties of TaOxNy thin films deposited by reactive magnetron sputtering
Authors:
Iulian PANA (1,2), Catalin VITELARU (1), Anca PARAU (1), Mariana BRAIC (1)
*
Affiliation:
1) National Institute for Optoelectronics, 409 Atomistilor St., 077125 Magurele, Ilfov county, Romania
2) Faculty of Physics, University of Bucharest, 405 Atomistilor St., Magurele, Ilfov county, Romania
E-mail
iulian.pana@inoe.ro
Keywords:
tantalum oxynitride films, reactive magnetron sputtering, optical properties
Abstract:
Tantalum oxy-nitrides (TaOxNy) films have attracted increasing interest lately, due to their high refractive index and transparency in the visible wavelength range, corrosion resistance, high hardness values, and chemical stability. A wide range of properties can be tuned by adjusting the incorporation of nitrogen in TaOx films [1], making them suitable to be used as selective solar absorbers, biocompatible coatings, photo-catalytic and electrochromic coatings [2]. In the reported study, TaOxNy films were obtained by conventional DC magnetron technique, a pure Ta target being sputtered in Ar/O2/N2 atmosphere. The optical emission spectroscopy (OES), coupled with electrical characteristics of the discharge and pressure monitoring were used to describe the reactive deposition process. The discharge was operated in power control mode, the pumping speed and the argon mass flow rate being kept constant. The process intervals were identified by investigating the hysteresis of the reactive magnetron sputtering process at the variation of either oxygen or nitrogen mass flow rates. The maximum reactivity, i.e the highest variation of the emission line intensities was achieved for mass flow values of 2.5 sccm O2 and 1 sccm N2, corresponding to 2.5 O2/N2 ratio, for a constant Ar mass flow of 5 sccm. By fixing the O2/N2 ratio at 2.5, the O2 and N2 flows were varied and the hysteresis in tantalum DC sputtering process was also analyzed, being identified a relevant process window where the optical properties of TaOxNy films can be tuned. Therefore, TaOxNy films were deposited on glass using the parameters obtained from the above-mentioned interval and were characterized using UV-Vis-NIR spectroscopy and EDS. The variation of refractive indices (3.3 ÷ 2.15), optical band gap (1.7 ÷ 3.6 eV) and elemental composition was shown to be well correlated with the process intervals identified in the Ar/O2/N2 environment.
References:
[1] S. Venkataraj et al., Multi-tehnique characterization of tantalum oxynitride films prepared by reactive direct current magnetron sputtering, Thin Solid Films 514 (2006).
[2] F. Zoubian et al., Potential of TaOxNy thin films deposited by reactive sputtering as antireflective coatings: composition and optical properties, Advanced Materials Research 324 (2011).
Acknowledgement:
This work was funded by Core Program, under the support of ANCSI, projects no. PN 16.40.01.01. and PN 16.40.01.02.
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