Intermediate Amorphous Layer Formation Mechanism at the Interface of Epitaxial CeO2 Layers and Si Substrates

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Abstract
The formation mechanism of an intermediate amorphous layer between epitaxially grown CeO2 layers and silicon substrates is studied using cross-sectional transmission electron microscopy and Auger electron spectroscopy. The intermediate amorphous layer thickness increases after annealing at 800°C in air, whereas it decreases somewhat after annealing in an ultrahigh vacuum. Auger in-depth analysis verifies that the intermediate amorphous layer is silicon dioxide. The intermediate oxide growth of the CeO2/Si structures due to intentional oxidation at 700∼900°C in a dry oxygen ambient is analyzed and the results indicate that the oxidation proceeds in an intermediate step between reaction limited and diffusion limited processes. The intermediate amorphous layer formation mechanism is concluded to be oxygen diffusion through CeO2 layers and successive oxidation of silicon at the interface.