High Frequency Thick Film BST Ferroelectric Phase Shifter

This paper discusses the performance of a thick-film ferroelectric phase shifter at high frequency. The phase shifter is fabricated from Barium Strontium Titanate (BST) thick-films on alumina substrates using a screen-printing method, and the electrodes are patterned using direct gravure-printing. We have achieved down to 40 μm gaps between electrodes using this method. Comparison between the theoretical response and experiment results will be presented. The extracted dielectric constants of the BST material using this phase shifter is also be presented here

Pulsed laser deposition of relaxor ferroelectric films

Heterostructures of perovskite relaxor ferroelectric (RFE) thin films onto La0.5Sr0.5CoO3, bottom electrode layers were grown by pulsed laser deposition on MgO(100) crystal substrates. The films were highly oriented, with (h00) planes parallel to the substrate surface, and demonstrated good dielectric and ferroelectric quality at room temperature. The studies of the dielectric properties of the films over the frequency range of 20 Hz .... 100 kHz and over the temperature range of 0...350°C revealed relaxor type behavior in the films. A diffuse ferroelectric phase transition and a shift of the maximum dielectric permittivity towards higher temperatures with increasing frequency were observed. Interferometric measurements of piezoelectric response of the heterostructures at room temperature yielded piezoelectric coefficients in the range of 25 ... 60 pm/V at 1 kHz, increasing up to 200 ... 250 pm/V at 60 Hz. The obtained results look promising for micromechanical applications of RFE thin films

Influence of layer interface parameters on dielectric characteristics of BSTO ferroelectric film planar capacitors

Ferroelectric BaxSr1-xTiO3 (BSTO) films were prepared on sapphire (r-cut) and MgO substrates using two preparation processes- RF sputtering aid the sol-gel rnethod. The structure of the films and interfaces were investigated by middle energy ion back scattering combined with ion channelling. Planar capacitors patterned on the film allowed the temperature dependence of capacitance and voltage-capacitance characteristics (VCC) to be measured at a frequency of 1 MHz. The influence of some interface parameters (e.g. the presence of intermediate layers, structural ordering of the BSTO surface layer, the type of film electrode) on dielectric characteristics, VCC hysteresis and tunability of the planar capacitors are discussed