PNNL

Abstract

Ultra-thin and continuous epitaxial films with relaxed lattice strain can potentially maintain more of its bulk physical and chemical properties and are useful as buffer layers. We study surface, interface and micro-structural properties of ultra-thin (~10-12 unit cells thick) epitaxial ceria films grown on single crystal YSZ substrates. The out-of -plane and in-plane lattice parameters indicate relaxation in the continuous film due to misfit dislocations seen by high-resolution transmission electron microscopy (HRTEM) and substrate roughness of ~1-2 unit cells, confirmed by atomic force microscopy and HRTEM. A combination of secondary sputtering, substrate roughness and surface reduction creating secondary phase were likely causes of surface roughness which should be reduced to a minimum level for effective use of it as buffer layers.