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

Abstract

The influence of high-energy (1.6 MeV) Ar2+ irradiation on the interfacial interaction between cerium oxide thin films (∼15 nm) with a SiO2/Si substrate is investigated using transmission electron microscopy, ultrahigh vacuum x-ray photoelectron spectroscopy (XPS), and a carbon monoxide (CO) oxidation catalytic reaction using ambient pressure XPS. The combination of these methods allows probing the dynamics of vacancy generation and its relation to chemical interactions at the CeO2/SiO2/Si interface. The results suggest that irradiation causes amorphization of some portion of CeO2 at the CeO2/SiO2/Si interface and creates oxygen vacancies due to the formation of Ce2O3 at room temperature. The subsequent ultra-high-vacuum annealing of irradiated films increases the concentration of Ce2O3 with the simultaneous growth of the SiO2 layer. Interactions with CO molecules result in an additional reduction of cerium and promote the transition of Ce2O3 to a silicate compound. Thermal annealing of thin films exposed to oxygen or carbon monoxide shows that the silicate phase is highly stabile even at 450 °C.

Swift heavy ion irradiation-induced amorphous iron and Fe–Si oxide phases in metallic 57Fe layer vacuum deposited on surface of SiO2/Si

“…However, such reduction can be possible in the presence of CO or H 2 which can be input by the swift heavy ion bombardment into the metal SiO 2 /Si interface. Similar cases have already been reported [34,43,44]. In the cases of high-energy Au and Ar ion irradiations of CeO 2 films on SiO 2 /Si substrates, the irradiation caused partial amorphization at the CeO 2 /SiO 2 /Si interface, and created oxygen vacancies due to the formation of Ce 2 O 3 at RT.…”

“…The formation of amorphous iron by heavy ion irradiation depends not only on the irradiation conditions (ion type, energy and fluence of the ion) but also on the material and method of production of both the coating and the substrate. In the case of SiO 2 and Si which are frequently used as substrates for iron deposits, or in their multilayers with iron [20][21][22][23][24][25], different irradiation conditions induced the formation of various nanostructured phases [26][27][28][29][30][31][32][33][34][35][36][37].…”

Irradiation-Driven Restructuring of UO2 Thin Films: Amorphization and Crystallization

“…The surface and cross-sectional morphology of the samples were investigated using a Helios Nanolab 600 (FEI - Thermo Fisher Scientific) with a dual electron/ion beam system. This microscope was also used to produce cross-sectional thin (50 nm) slices from the samples for transmission electron microscopy (TEM). − The morphology and structure of the slices were investigated using a Titan-300 (FEI) microscope with a resolution of 0.136 nm in scanning TEM mode and about 0.1 nm information limit in high-resolution TEM mode. The Titan is equipped with an energy-dispersive X-ray spectroscopy (EDS, Oxford Inca) system containing a Si–Li detector (energy resolution of ∼130 eV at 5.9 keV).…”

Hyperstoichiometric Uranium Dioxides: Rapid Synthesis and Irradiation-Induced Structural Changes

“…A Magellan 400 (FEI) field-emission scanning electron microscope (SEM) was used to investigate the microstructure of the products. In addition, cross-sectional slices from thin films were taken for transmission electron microscopy (TEM) analysis using a Helios NanoLab 600 system as previously described . The morphological and structural investigations of slices were conducted with a Titan-300 (FEI) TEM.…”