Interface structures and periodic film distortions induced by substrate-surface steps in Gd-doped ceria thin-film growth.

Gadolinium-doped ceria (Ce0.8Gd0.2O2-δ) thin films were grown on single-crystal (001) LaAlO3 (LAO) substrates by a pulsed laser ablation. The transmission electron microscope observation reveals a unique type of periodic film distortion along the film/substrate interface. Each distorted film area is associated with a few substrate-surface steps and the spacing between these distorted areas is about 50 μm. The distortion starts at the substrate-surface steps and extends into the film along one of the {111} planes at the step-forward direction. The {111} planar defects induced by the nearby steps can interact with each other to form a planar defect network. The structure of the (001) LAO surface, the structure of the film/substrate interface, and the mechanism of the formation of these {111} planar defects have been analyzed using a high-resolution electron microscopy. Structural models for these planar defects and their interaction are suggested. [ABSTRACT FROM AUTHOR]