Structure and dielectrical properties of (Pb,Sr)TiO3 thin films for tunable microwave device

Abstract

The object of investigation is represented by PbxSr1-xTiO3 (PST) thin films, which were fabricated by the alkoxide-based solgel method on Pt/Ti/SiO2/Si substrate. We have investigated both structural and dielectric properties of PST thin films aimed to tunable microwave device applications as a function of Pb/Sr ratio. PST thin films showed typical polycrystalline structure with a dense microstructure without secondary phase formation. Dielectric properties of PST films were found as strongly dependent on Pb/Sr composition ratio. Increasing of Ph content leads to simultaneous increasing of both dielectric constant and dielectric loss characteristics of PST films. The figure of merit (FOM) parameter (FOM = (%) tunability/tan delta (%)) reached a maximal value of 27.5 corresponding to Pb/Sr ratio of 40/60. The tunability increased with increasing Pb content. The dielectric constants, dielectric loss and tunability of the PST thin films at Pb/Sr ratio of 40/60 measured at 100 kHz were 335, 0.0174 and 47.89%, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.