Irradiation-induced reactions at the CeO₂/SiO₂/Si interface

Area of Science:

• Materials Science
• Surface Science
• Catalysis

Background:

• Cerium oxide (CeO2) is a key material in catalysis and thin-film applications.
• Understanding interfacial interactions is crucial for device performance and stability.
• High-energy ion irradiation is a method to modify material properties.

Purpose of the Study:

• Investigate the effects of Ar2+ irradiation on CeO2 thin films on SiO2/Si substrates.
• Analyze the generation of oxygen vacancies and chemical changes at the interface.
• Evaluate the catalytic activity and thermal stability of the modified interface.

Main Methods:

• Transmission electron microscopy (TEM) for structural analysis.
• Ultrahigh vacuum X-ray photoelectron spectroscopy (XPS) for chemical state analysis.
• Ambient pressure XPS for in-situ catalytic reaction studies (CO oxidation).

Main Results:

• Irradiation-induced amorphization of CeO2 and formation of oxygen vacancies (Ce2O3) at room temperature.
• Annealing increased Ce2O3 concentration and SiO2 layer growth.
• CO interaction led to further cerium reduction and formation of a stable silicate phase.
• The silicate phase remained stable up to 450 °C.

Conclusions:

• High-energy ion irradiation effectively modifies the CeO2/SiO2/Si interface by creating defects and altering chemical states.
• The formation of a stable silicate phase has implications for interfacial engineering in electronic and catalytic devices.
• The study highlights the interplay between irradiation, annealing, and gas interactions in determining interfacial properties.