Influence of DC magnetron sputtering reaction gas on structural and optical characteristics of Ce-oxide thin films

Hussein A. Miran, Zhong Tao Jiang, Mohammednoor Altarawneh, Jean Pierre Veder, Zhi feng Zhou, M. Mahbubur Rahman, Zainab N. Jaf, Bogdan Z. Dlugogorski

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The influence of the reaction gas composition during the DC magnetron sputtering process on the structural, chemical and optical properties of Ce-oxide thin films was investigated. X-ray diffraction (XRD) studies confirmed that all thin films exhibited a polycrystalline character with cubic fluorite structure for cerium dioxide. X-ray photoelectron spectroscopy (XPS) analyses revealed that cerium is present in two oxidation states, namely as CeO 2 and Ce 2 O 3 , at the surface of the films prepared at oxygen/argon flow ratios between 0% and 7%, whereas the films are completely oxidized into CeO 2 as the aforementioned ratio increases beyond 14%. Various optical parameters for the thin films (including an optical band gap in the range of 2.25–3.1 eV) were derived from the UV–Vis reflectance. A significant change in the band gap was observed as oxygen/argon flow ratio was raised from 7% to 14% and this finding is consistent with the high-resolution XPS analysis of Ce 3d that reports a mixture of Ce 2 O 3 and CeO 2 in the films. Density functional theory (DFT+U) implemented in the Cambridge Serial Total Energy Package (CASTEP) was carried out to simulate the optical constants of CeO 2 clusters at ground state. The computed electronic density of states (DOSs) of the optimized unit cell of CeO 2 yields a band gap that agrees well with the experimentally measured optical band gap. The simulated and measured absorption coefficient (α) exhibited a similar trend and, to some extent, have similar values in the wavelength range from 100 to 2500 nm. The combined results of this study demonstrate good correlation between the theoretical and experimental findings.

Original languageEnglish
Pages (from-to)16450-16458
Number of pages9
JournalCeramics International
Volume44
Issue number14
DOIs
Publication statusPublished - 1 Oct 2018
Externally publishedYes

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Magnetron sputtering
Oxide films
Argon
Gases
Optical band gaps
Cerium
Thin films
Energy gap
X ray photoelectron spectroscopy
Oxygen
Electronic density of states
Optical constants
Fluorspar
Discrete Fourier transforms
Chemical properties
Ground state
Density functional theory
Structural properties
Optical properties
X ray diffraction

Cite this

Miran, H. A., Jiang, Z. T., Altarawneh, M., Veder, J. P., Zhou, Z. F., Rahman, M. M., ... Dlugogorski, B. Z. (2018). Influence of DC magnetron sputtering reaction gas on structural and optical characteristics of Ce-oxide thin films. Ceramics International, 44(14), 16450-16458. https://doi.org/10.1016/j.ceramint.2018.06.059
Miran, Hussein A. ; Jiang, Zhong Tao ; Altarawneh, Mohammednoor ; Veder, Jean Pierre ; Zhou, Zhi feng ; Rahman, M. Mahbubur ; Jaf, Zainab N. ; Dlugogorski, Bogdan Z. / Influence of DC magnetron sputtering reaction gas on structural and optical characteristics of Ce-oxide thin films. In: Ceramics International. 2018 ; Vol. 44, No. 14. pp. 16450-16458.
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abstract = "The influence of the reaction gas composition during the DC magnetron sputtering process on the structural, chemical and optical properties of Ce-oxide thin films was investigated. X-ray diffraction (XRD) studies confirmed that all thin films exhibited a polycrystalline character with cubic fluorite structure for cerium dioxide. X-ray photoelectron spectroscopy (XPS) analyses revealed that cerium is present in two oxidation states, namely as CeO 2 and Ce 2 O 3 , at the surface of the films prepared at oxygen/argon flow ratios between 0{\%} and 7{\%}, whereas the films are completely oxidized into CeO 2 as the aforementioned ratio increases beyond 14{\%}. Various optical parameters for the thin films (including an optical band gap in the range of 2.25–3.1 eV) were derived from the UV–Vis reflectance. A significant change in the band gap was observed as oxygen/argon flow ratio was raised from 7{\%} to 14{\%} and this finding is consistent with the high-resolution XPS analysis of Ce 3d that reports a mixture of Ce 2 O 3 and CeO 2 in the films. Density functional theory (DFT+U) implemented in the Cambridge Serial Total Energy Package (CASTEP) was carried out to simulate the optical constants of CeO 2 clusters at ground state. The computed electronic density of states (DOSs) of the optimized unit cell of CeO 2 yields a band gap that agrees well with the experimentally measured optical band gap. The simulated and measured absorption coefficient (α) exhibited a similar trend and, to some extent, have similar values in the wavelength range from 100 to 2500 nm. The combined results of this study demonstrate good correlation between the theoretical and experimental findings.",
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Miran, HA, Jiang, ZT, Altarawneh, M, Veder, JP, Zhou, ZF, Rahman, MM, Jaf, ZN & Dlugogorski, BZ 2018, 'Influence of DC magnetron sputtering reaction gas on structural and optical characteristics of Ce-oxide thin films', Ceramics International, vol. 44, no. 14, pp. 16450-16458. https://doi.org/10.1016/j.ceramint.2018.06.059

Influence of DC magnetron sputtering reaction gas on structural and optical characteristics of Ce-oxide thin films. / Miran, Hussein A.; Jiang, Zhong Tao; Altarawneh, Mohammednoor; Veder, Jean Pierre; Zhou, Zhi feng; Rahman, M. Mahbubur; Jaf, Zainab N.; Dlugogorski, Bogdan Z.

In: Ceramics International, Vol. 44, No. 14, 01.10.2018, p. 16450-16458.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Influence of DC magnetron sputtering reaction gas on structural and optical characteristics of Ce-oxide thin films

AU - Miran, Hussein A.

AU - Jiang, Zhong Tao

AU - Altarawneh, Mohammednoor

AU - Veder, Jean Pierre

AU - Zhou, Zhi feng

AU - Rahman, M. Mahbubur

AU - Jaf, Zainab N.

AU - Dlugogorski, Bogdan Z.

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Y1 - 2018/10/1

N2 - The influence of the reaction gas composition during the DC magnetron sputtering process on the structural, chemical and optical properties of Ce-oxide thin films was investigated. X-ray diffraction (XRD) studies confirmed that all thin films exhibited a polycrystalline character with cubic fluorite structure for cerium dioxide. X-ray photoelectron spectroscopy (XPS) analyses revealed that cerium is present in two oxidation states, namely as CeO 2 and Ce 2 O 3 , at the surface of the films prepared at oxygen/argon flow ratios between 0% and 7%, whereas the films are completely oxidized into CeO 2 as the aforementioned ratio increases beyond 14%. Various optical parameters for the thin films (including an optical band gap in the range of 2.25–3.1 eV) were derived from the UV–Vis reflectance. A significant change in the band gap was observed as oxygen/argon flow ratio was raised from 7% to 14% and this finding is consistent with the high-resolution XPS analysis of Ce 3d that reports a mixture of Ce 2 O 3 and CeO 2 in the films. Density functional theory (DFT+U) implemented in the Cambridge Serial Total Energy Package (CASTEP) was carried out to simulate the optical constants of CeO 2 clusters at ground state. The computed electronic density of states (DOSs) of the optimized unit cell of CeO 2 yields a band gap that agrees well with the experimentally measured optical band gap. The simulated and measured absorption coefficient (α) exhibited a similar trend and, to some extent, have similar values in the wavelength range from 100 to 2500 nm. The combined results of this study demonstrate good correlation between the theoretical and experimental findings.

AB - The influence of the reaction gas composition during the DC magnetron sputtering process on the structural, chemical and optical properties of Ce-oxide thin films was investigated. X-ray diffraction (XRD) studies confirmed that all thin films exhibited a polycrystalline character with cubic fluorite structure for cerium dioxide. X-ray photoelectron spectroscopy (XPS) analyses revealed that cerium is present in two oxidation states, namely as CeO 2 and Ce 2 O 3 , at the surface of the films prepared at oxygen/argon flow ratios between 0% and 7%, whereas the films are completely oxidized into CeO 2 as the aforementioned ratio increases beyond 14%. Various optical parameters for the thin films (including an optical band gap in the range of 2.25–3.1 eV) were derived from the UV–Vis reflectance. A significant change in the band gap was observed as oxygen/argon flow ratio was raised from 7% to 14% and this finding is consistent with the high-resolution XPS analysis of Ce 3d that reports a mixture of Ce 2 O 3 and CeO 2 in the films. Density functional theory (DFT+U) implemented in the Cambridge Serial Total Energy Package (CASTEP) was carried out to simulate the optical constants of CeO 2 clusters at ground state. The computed electronic density of states (DOSs) of the optimized unit cell of CeO 2 yields a band gap that agrees well with the experimentally measured optical band gap. The simulated and measured absorption coefficient (α) exhibited a similar trend and, to some extent, have similar values in the wavelength range from 100 to 2500 nm. The combined results of this study demonstrate good correlation between the theoretical and experimental findings.

KW - Cerium oxide

KW - DFT

KW - Optical parameters

KW - X-ray photoelectron spectroscopy

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