Nucleation and Growth of Nanophasic CeO₂ Thin Films by Plasma‐Enhanced CVD

Abstract

Nanophasic CeO 2 -based thin films were grown at low temperatures on SiO 2 and Si(100) by plasma-enhanced (PE) CVD from a Ce IV b-diketonate first generation precursor. Film depositions were carried out in low-pressure Ar±O 2 plasmas at temperatures between 150 C and 300 C. The film microstructure was investigated by glancing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM), while the surface and in-depth chemical composition was studied by X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS), respectively. Optical properties were analyzed by UV-vis optical absorption. Nanostructured CeO 2 -based films, with crystal size less than 6 nm and a controllable Ce IV /Ce III ratio, were obtained at temperatures even lower than that required for precursor vaporization (170 C). In particular, TEM analyses showed an island growth mode and different microstructural features as a function of the substrate used.

Innovative Approaches to Oxide Nanosystems: CeO2‐ZrO2 Nanocomposites by a Combined PE‐CVD/Sol–Gel Route

“…In fact, the presence of a large number of ±OH groups in the zirconia xerogel, acting as nucleation sites, might strongly favor Ce(dpm) 4 decomposition. [6] The low Ce content might also be responsible for the almost unperturbed thermal evolution of zirconia. On the other hand, different results were obtained for samples belonging to set B (Fig.…”

“…[23,24] Moreover, the plasma action in PE-CVD permits the achievement of nanosystems thanks to the competition between deposition/ablation phenomena characterizing glow discharges. [6] In these processes, plasma promotes and activates chemical reactions both in the gas phase and on the substrate (Fig. 1b), producing an intimate intermixing between the SG host matrix and the PE-CVD guest phase.…”

“…[1] The application of such systems is based on the facile Ce III « Ce IV switching, influencing the oxygen storage capacity (OSC) of ceria, [2,3] and on the improvement of thermal stability and redox properties featured by ceria±zirconia mixed oxides with respect to pure CeO 2 . [4,5] The functional properties of Ce-Zr-O materials might be further enhanced by exploiting the synergy between oxygen deficiency and the peculiar characteristics of nanostructured systems, [6] that can be tailored by an adequate choice of the synthetic approach and processing conditions. [7,8] As a matter of fact, two main pathways to the ªnanoº dimensional scale can be identified.…”

Structural and Spectroscopic Investigation of Ceria Nanofibers Fabricated by Electrospinning Process

“…26 Barreca et al studied the oxidation states of Ce in CeO 2 thin films obtained by plasma-enhanced chemical vapor deposition (PECVD) using XPS. 17 They showed that the obtained CeO 2-x films had a tunable Ce…”

“…Nano-sized CeO 2 is used in many applications like cosmetic materials, high-storage capacitor devices, 16 buffer layers for conductors, [17][18][19] fuel cells, 20,21 and optical devices.…”