Enhanced dielectric and tunable characteristics of K-doped Ba0.5Sr0.5TiO3 thin films prepared by pulsed laser deposition

► Potassium-doped BaSrTiO3 films prepared by pulsed laser deposition ► Excellent tunability of 77% and figure of merit of 65 at 400 kV cm− 1 ► Strong dependence of K-doping level on dielectric and tunable characteristics ► Potential correlations to grain size, strain and surface roughness