Dielectric properties of pulsed laser deposited SrTiO₃ thin films

Low frequency dielectric loss and nonlinearity in pulsed laser deposited SrTiO3 thin films were studied. A low loss tangent in the order of 10-4, close to the level found in SrTiO3 single crystals, was observed. Combined with a large tunability, this resulted in a figure of merit for frequency and phase agile materials that can rival that observed in single crystals. The SrTiO3 thin films with thickness ranging from 25 nm to 2.5μ were grown on SrRuO3 electrode layers. The loss depends strongly on the thickness, but differently above and below T approx. 80 K. Our result suggests that, in the high temperature regime, the interfacial dead layer effect dominates while, in the low temperature regime, the losses related to the structural phase transition and quantum fluctuations are important. The effect of interfacial potential was studied by using different electrode materials that result in different Schottky barriers.