  The application of a substrate bias during rf magnetron sputtering alters the
crystalline structure, grain morphology, lattice strain and composition of
BaxSr1-xTiO3 thin films. As a result, the dielectric properties of
Pt/BaxSr1-xTiO3/Pt parallel-plate capacitors change significantly. With
increasing substrate bias we observe a clear shift of the ferroelectric to
paraelectric phase transition towards higher temperature, an increase of the
dielectric permittivity and tunability at room temperature, and a deterioration
of the dielectric loss. To a large extent these changes correlate to a gradual
increase of the tensile in-plane film strain with substrate bias and an abrupt
change in film composition.
