## Pavel Ondračka, David Nečas, Michele Carette, Stéphane Elisabeth, David Holec, Agnés Granier, Antoine Goullet, Lenka Zajíčková, Mireille Richard-Plouet

# Unravelling local environments in mixed TiO2–SiO2 thin films by XPS and ab initio calculations

## Applied Surface Science 510 (2020) 145056

Mixed Ti(x)Si(1−x)O₂ oxide can exhibit a partial phase separation of the TiO₂ and SiO₂ phases at the atomic level. The quantification of TiO₂–SiO₂ mixing in the amorphous material is complicated and was so far done mostly by infrared spectroscopy. We developed a new approach to the fitting of X-ray photoelectron spectroscopy data for the quantification of partial phase separation in amorphous Ti(x)Si(1−x)O₂ thin films deposited by plasma enhanced chemical vapour deposition. Several fitting constraints reducing the total number of degrees of freedom in the fits and thus the fit uncertainty were obtained by using core electron binding energies predicted by density functional theory calculations on Ti(x)Si(1−x)O₂ amorphous supercells. Consequently, a decomposition of the O 1s peak into TiO₂, SiO₂ and mixed components was possible. The component areas ratios were compared with the ratios predicted by older theoretical models based on the atomic environment statistics and we also developed several new models corresponding to more realistic atomic structure and partial mixing. Based on the comparison we conclude that the studied films are mostly disordered, with only a moderate phase separation.

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DOI: 10.1016/j.apsusc.2019.145056

You can also contact one of the authors: pavel.ondracka@gmail.com, yeti@physics.muni.cz, lenkaz@physics.muni.cz