Pb 0.3 Sr 0.7 TiO 3 thin films for high-frequency phase shifter applications

Abstract

Pb 0.3 Sr 0.7 TiO 3 ( PST 30 ) thin films were synthesized on platinized silicon (Pt∕Si) and lanthanum aluminate (LAO) substrates using chemical solution deposition technique. The films on LAO substrate were highly (100) oriented, whereas the films on Pt∕Si substrate were polycrystalline. The low dielectric loss in the PST30∕LAO films makes them attractive for fabricating tunable dielectric devices. An eight-element coupled microstrip phase shifter was fabricated on PST30∕LAO film and tested in the frequency range ∼15–17GHz. The maximum figure of merit (κ=phase shift per dB loss) of ∼56°∕dB was obtained for PST30 film, which was better than commonly observed value in pure barium strontium titanate films. This makes PST30 a potential candidate material for further investigations for microwave applications.