Applied Physics Letters · 2005 · 45 citations · 16 references
Natural SciencesMaterials EngineeringMaterials ScienceElectronic MaterialsMaterials CharacterizationThin FilmsDielectric MaterialsDielectric PropertiesDielectricsMicrowave MaterialsThin Film Electrical PropertiesThin Film StrainBarium TitanateDirectional DependenceEpitaxial StrainFilm ThicknessMicrowave Dielectric PropertiesResidual StrainStrain RelaxationStrontium Barium Titanate
In-plane dielectric properties of ⟨110⟩ oriented epitaxial (Ba0.60Sr0.40)TiO3 thin films in the thickness range from 25–1200nm have been investigated under the influence of anisotropic epitaxial strains from ⟨100⟩ NdGaO3 substrates. The measured dielectric properties show strong residual strain and in-plane directional dependence. Below 150nm film thickness, there appears to be a phase transition due to the anisotropic nature of the misfit strain relaxation. In-plane relative permittivity is found to vary from as much as 500–150 along [11¯0] and [001] respectively, in 600nm thick films, and from 75 to 500 overall. Tunability was found to vary from as much as 54% to 20% in all films and directions, and in a given film the best tunability is observed along the compressed axis in a mixed strain state, 54% along [11¯0] in the 600nm film for example.
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Room-temperature ferroelectricity in strained SrTiO3
J. H. Haeni, Patrick Irvin, Wontae Chang et al. · Nature · 2004 · 2.1K citations · Full text