Source:Doktorsavhandlingar vid Chalmers Tekniska Hogskola, Chalmers Tekniska Hogskola, Goteborg, Sweden, Number 1414, p.1-6 (1998)
Keywords:annealing, Epitaxial growth, Ferroelectric materials, morphology, Phase composition, Subgrains, substrates, thin films
An epitaxial (001) SrTiO3 thin film, pulsed laser deposited on a LaAlO3 substrate, has been investigated using analytical transmission electron microscopy and x-ray diffraction. The film contained two different phases, with sharp compositional boundaries between the phases. One phase was 18% Sr-deficient, exhibited a columnar subgrain morphology, and had a large spread in the lattice parameter values. The other phase was stoichiometric SrTiO3, single crystalline, and defect-free. The results show that film stoichiometry is important if interfacial strain and columnar growth is to be avoided. A Sr-rich target and high-temperature annealing are two suggested precautions to improve homogeneity and stoichiometry.
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