Defect structure in homoepitaxial non-stoichiometric strontium titanate thin films
- 1 March 2000
- journal article
- research article
- Published by Taylor & Francis in Philosophical Magazine A
- Vol. 80 (3), 621-637
- https://doi.org/10.1080/01418610008212072
Abstract
The defect structure of non-stoichiometric strontium titanate thin films epitaxially grown on SrTiO3(100) substrates by pulsed-laser deposition was studied using transmission electron microscopy and X-ray diffraction. The A-site-excess SrTiO3 thin film adopted a completely unrelaxed pseudomorphic perovskite structure with an enlarged lattice parameter normal to the surface. Excess SrO was accommodated as Ruddlesden-Popper planar faults showing a peculiar three-dimensional mosaic structure, without forming secondary phases or dislocations due to non-stoichiometry. Biaxial compressive stress induced by lattice mismatch between the film and substrate was estimated at 9,7 GPa. Such a highly strained film is attributable to planar fault formation, which increases the cell volume and suppresses misfit dislocations. The B-site-excess SrTiO3 thin-film microstructure consisted of crystalline SrTiO3 and amorphous TiO2-rich phases. The slight increase in the lattice parameter normal to the surface and crystallographic shear structure with a TiO2 double layer suggest the low solubility of excess TiO2.Keywords
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