Fabrication and Characterization of Thermally Oxidized Tungsten-Based Thin Films for Application in Cold Field Emission Sources

0584784 - ÚPT 2024 SK eng A - Abstract
Košelová, Zuzana - Knápek, Alexandr - Fohlerová, Z.
Fabrication and Characterization of Thermally Oxidized Tungsten-Based Thin Films for Application in Cold Field Emission Sources.
SURFINT-SREN VIII. Extended Abstract Book. Bratislava: Comenius University, 2023 - (Brunner, R.). s. 20-21. ISBN 978-80-223-5713-5.
[SURFINT-SREN /8./ Progress in Applied Surface, Interface and Thin Film Science, Solar Renewable Energy News 2023. 20.11.2023-22.11.2023, Bratislava]
R&D Projects: GA TA ČR(CZ) FW03010504
Research Infrastructure: CzechNanoLab - 90110
Institutional support: RVO:68081731
Keywords : Thermal Oxidation * Tungsten Tips * XPS * AFM * Cold Field Emmision
OECD category: Coating and films

Thermal oxidation is employed to create thin oxide coatings on surfaces, with applications in cold field electron emission sources. Tungsten is a preferred choice for such applications in commercial microscopy due to its desirable attributes, which can be further improved through the deposition of a thin layer, enhancing emission characteristics and extending emitter lifespan. Tungsten oxide, known for its resistance to corrosion, owes its durability to a stable crystal lattice and strong chemical bonds with oxygen atoms. The chosen method, thermal oxidation, offers material coverage without requiring sophisticated equipment. The process involves subjecting tungsten to elevated temperatures and pressures, controlling oxide layer thickness and properties. Initial experiments revealed that lower pressure significantly reduced roughness, influencing subsequent experiments. Thermal oxidation parameters included pre-cleaning, preheating, treatment, and cooling phases. Testing the resulting tungsten oxide layers involved assessing morphology and chemical composition. Achieving a relatively uniform, low-roughness coating is crucial for cold field emission cathode tips. While thermal oxidation generally reduces roughness, our emitters´ lower initial roughness led to an increase post-oxidation. At 80 Torr, a roughness of Ra = 324 nm was observed, whereas at 10 Torr, a significantly lower Ra = 227 nm was achieved. This research aims to determine the suitability of these tungsten oxide layers for high-quality electron-emitting devices like electron guns.

Permanent Link: https://hdl.handle.net/11104/0352629