Applied Physics Letters · 2006 · 27 citations · 18 references
Natural SciencesElectrical EngineeringMaterials ScienceCeramic MaterialsMicrowave EngineeringThin FilmsDielectricsMicrowave MaterialsStrain EngineeringThin Film Electrical PropertiesThin Film StrainThin-film MaterialsCapacitanceCompressive StrainCritical ThicknessFilm StrainFilm ThicknessMicrowave DevicesMicrowave Dielectric PropertiesStrain Effects
Polycrystalline Ba0.6Sr0.4TiO3 (BST) films grown on r-plane sapphire exhibit strong variation of in-plane strain over the thickness range of 25–400nm. At a critical thickness of ∼200nm, the films are strain relieved; in thinner films, the strain is tensile, while compressive strain was observed in the 400nm film. Microwave properties of the films were measured from 1to20GHz by the interdigital capacitor method. A capacitance tunability of 64% was observed in the 200nm film, while thinner films showed improved Q factor. These results demonstrate the possibility of incorporating frequency agile BST-based devices into the silicon on sapphire process.
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