Unusual strain dependence of tunability in highly (100)-oriented Mn-doped barium strontium stannate titanate thin films

Highly (100)-oriented (Ba_0.7Sr_0.3)(Sn _0.2Ti_0.8-xMn_x)O₃ (Mn-BSSnT) (x=0%, 0.2%, 0.4%, 0.6%, and 1%) thin films were fabricated on (La_0.7Sr _0.3)CoO₃/LaAlO₃ substrates by pulsed laser deposition. Both elastic residual strain and inhomogeneous strain were measured by x-ray diffraction techniques. The effect of strain on dielectric properties of the Mn-BSSnT thin films was investigated as a function of the Mn content. It was found that inhomogeneous strain has a greater effect on the tunability than the elastic residual strain does. The tunability decreases with increasing inhomogeneous strain and can be manipulated by changing Mn doping content, which is beneficial to real tunable device applications. © 2008 American Institute of Physics.