%0 Journal Article
%A C.L Canedy
%A H Li
%A S.P Alpay
%A L Salamanca-Riba
%A A.L Roytburd
%A Ramamoorthy Ramesh
%B Applied Physics Letters
%D 2000
%G eng
%I American Institute of Physics Inc.
%P 1695-1697
%R 10.1063/1.1308531
%T Dielectric properties in heteroepitaxial Ba0.6Sr0.4TiO3 thin films: Effect of internal stresses and dislocation-type defects
%V 77
%X A series of heteroepitaxial Ba0.6Sr0.4TiO3 were grown on 0.29(LaAlO3):0.35(Sr2TaAlO6) substrates using pulsed-laser deposition. X-ray characterization revealed compressive in-plane stresses in the thinnest films, which were relaxed in a continuous fashion with increasing thickness. A theoretical treatment of the misfit strain was in good agreement with the measured out-of-plane lattice parameter. The low-frequency dielectric constant was measured to be significantly less than the bulk value and found to decrease rapidly for films less than 100 nm. A thermodynamic model was developed to understand the reduction in dielectric constant. By observing the microstructure using plan-view and cross-section transmission electron microscopy, we identified local strain associated with a threading dislocation density on the order of 1011 cm-2 as a possible mechanism for dielectric degradation in these films. © 2000 American Institute of Physics.