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Dielectric properties in heteroepitaxial Ba0.6Sr0.4TiO3 thin films: Effect of internal stresses and dislocation-type defects
 

Summary: Dielectric properties in heteroepitaxial Ba0.6Sr0.4TiO3 thin films: Effect
of internal stresses and dislocation-type defects
C. L. Canedy, Hao Li,a)
S. P. Alpay, L. Salamanca-Riba, A. L. Roytburd, and R. Ramesh
Department of Materials and Nuclear Engineering, University of Maryland, College Park,
Maryland 20742
Received 8 May 2000; accepted for publication 11 July 2000
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.
S0003-6951 00 00937-2

  

Source: Alpay, S. Pamir - Department of Materials Science and Engineering, University of Connecticut

 

Collections: Materials Science