TY - JOUR

T1 - Unravelling local environments in mixed TiO2–SiO2 thin films by XPS and ab initio calculations

AU - Ondračka, Pavel

AU - Nečas, David

AU - Carette, Michèle

AU - Elisabeth, Stephane

AU - Holec, David

AU - Granier, Agnès

AU - Goullet, Antoine

AU - Zajíčková, Lenka

AU - Richard-Plouet, Mireille

N1 - Publisher Copyright: © 2020 Elsevier B.V.

PY - 2020/4/30

Y1 - 2020/4/30

N2 - Mixed Ti xSi 1 − xO 2 oxide can exhibit a partial phase separation of the TiO 2 and SiO 2 phases at the atomic level. The quantification of TiO 2–SiO 2 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 xSi 1 − xO 2 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 xSi 1 − xO 2 amorphous supercells. Consequently, a decomposition of the O 1s peak into TiO 2, SiO 2 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.

AB - Mixed Ti xSi 1 − xO 2 oxide can exhibit a partial phase separation of the TiO 2 and SiO 2 phases at the atomic level. The quantification of TiO 2–SiO 2 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 xSi 1 − xO 2 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 xSi 1 − xO 2 amorphous supercells. Consequently, a decomposition of the O 1s peak into TiO 2, SiO 2 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.

UR - http://www.scopus.com/inward/record.url?scp=85078889054&partnerID=8YFLogxK

U2 - 10.1016/j.apsusc.2019.145056

DO - 10.1016/j.apsusc.2019.145056

M3 - Article

VL - 510.2020

JO - Applied surface science

JF - Applied surface science

SN - 0169-4332

IS - 30 April

M1 - 145056

ER -