Correlation between material properties of ferroelectric thin films and design parameters for microwave device applications: Modeling examples and experimental verification

The application of thin ferroelectric films for frequency and phase agile c omponents is the topic of interest of many research groups worldwide. Conse quently, proof-of-concepts (POC) of different tunable microwave components using either (HTS, metal)/ferroelectric thin film/dielectric heterostructur es or (thick, thin) film "flip-chip" technology have been reported. Either as ferroelectric thin film characterization tools or from the point of view of circuit implementation approach, both configurations have their respect ive advantages and limitations. However, we believe that because of the pro gress made so far using the heterostructure (i.e., multilayer) approach, an d due to its intrinsic features such as planar configuration and monolithic integration, a study on the correlation of circuit geometry aspects and fe rroelectric material properties could accelerate the insertion of this tech nology into working systems. In this paper, we will discuss our study perfo rmed on circuits based on microstrip lines at frequencies above 10 GHz, whe re the multilayer configuration offers greater ease of insertion due to cir cuit's size reduction. Modeled results of relevant circuit parameters such as the characteristic impedance, effective dielectric constant, and attenua tion as a function of ferroelectric film's dielectric constant, tan delta, and thickness, will be presented for SrTiO3 and BaxSr1-xTiO3 ferroelectric films. A comparison between the modeled and experimental data for some of t hese parameters will be presented.