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In-situ monitoring of tungsten oxides reduction during deuterium plasma exposure by spectroscopic ellipsometry
In this work, we investigate the optical properties variation of thermally grown W oxides during the exposure to low energy deuterium (D) plasma. In-situ ellipsometry in the 400–1000 nm range was coupled to ex-situ diagnostics, such as X-ray photoelectron spectroscopy (XPS) and focused ion beam coupled to scanning electron microscopy (FIB-SEM), to probe the evolution of chemical and morphological properties of the W oxides. First, a 70 nm thick WO3 layer was exposed to D plasma at a surface temperature of 650 K. An important reduction of the oxide layer was observed by FIB-SEM, and in-situ ellipsometry showed the evolution of the optical constants n and k of the oxide towards the ones of pure W metal. Secondly, a 300 nm thick WO3 layer was exposed to D plasma at a surface temperature below 373 K. In order to follow the oxide evolution step by step, we alternated in-situ ellipsometry and XPS surface characterization. A quite similar evolution of the optical constants was observed, in particular an increase of the extinction coefficient k in the near infrared, which was linked to a progressive reduction of the oxidation level at the surface, as seen by XPS. Interestingly, the reduction of the oxide at 373 K was below the resolution of the FIB-SEM. This observation indicates that ellipsometry in the 400–1000 nm range is able to follow in-situ the reduction of WO3 oxides by D plasma with high surface sensitivity.
In-situ monitoring of tungsten oxides reduction during deuterium plasma exposure by spectroscopic ellipsometry
In this work, we investigate the optical properties variation of thermally grown W oxides during the exposure to low energy deuterium (D) plasma. In-situ ellipsometry in the 400–1000 nm range was coupled to ex-situ diagnostics, such as X-ray photoelectron spectroscopy (XPS) and focused ion beam coupled to scanning electron microscopy (FIB-SEM), to probe the evolution of chemical and morphological properties of the W oxides. First, a 70 nm thick WO3 layer was exposed to D plasma at a surface temperature of 650 K. An important reduction of the oxide layer was observed by FIB-SEM, and in-situ ellipsometry showed the evolution of the optical constants n and k of the oxide towards the ones of pure W metal. Secondly, a 300 nm thick WO3 layer was exposed to D plasma at a surface temperature below 373 K. In order to follow the oxide evolution step by step, we alternated in-situ ellipsometry and XPS surface characterization. A quite similar evolution of the optical constants was observed, in particular an increase of the extinction coefficient k in the near infrared, which was linked to a progressive reduction of the oxidation level at the surface, as seen by XPS. Interestingly, the reduction of the oxide at 373 K was below the resolution of the FIB-SEM. This observation indicates that ellipsometry in the 400–1000 nm range is able to follow in-situ the reduction of WO3 oxides by D plasma with high surface sensitivity.
In-situ monitoring of tungsten oxides reduction during deuterium plasma exposure by spectroscopic ellipsometry
F. Pappalardo (author) / L. Rayneau (author) / C. Martin (author) / M. Cabie (author) / E. Salomon (author) / T. Angot (author) / G. Cartry (author) / R. Bisson (author) / M. Minissale (author)
2024
Article (Journal)
Electronic Resource
Unknown
Metadata by DOAJ is licensed under CC BY-SA 1.0
| Elsevier | 2024
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