@article{tombak_maria_ayguavives_jin_stauf_kingon_mortazawi_2002, title={Tunable barium strontium titanate thin film capacitors for RF and microwave applications}, volume={12}, ISSN={["1558-1764"]}, DOI={10.1109/7260.975716}, abstractNote={The measurement results for thin film barium strontium titanate (BST) based voltage tunable capacitors intended for RF applications are reported. At 9 V DC, BST capacitors fabricated using MOCVD (metalorganic chemical vapor deposition) method achieved 71% (3.4:1) tunability. The measured device quality factor (Q) for BST varactors is comparable with the device Q for commercially available varactor diodes of similar capacitance. The typical dielectric loss tangent was in the range 0.003-0.009 at VHF. Large signal measurement and modeling results for BST thin film capacitors are also presented.}, number={1}, journal={IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS}, author={Tombak, A and Maria, JP and Ayguavives, F and Jin, Z and Stauf, GT and Kingon, AI and Mortazawi, A}, year={2002}, month={Jan}, pages={3–5} }
 @article{ayguavives_jin_tombak_maria_mortazawi_kingon_2001, title={Contribution of dielectric and metallic losses in RF/microwave tunable varactors using (Ba,Sr)TiO3 thin films}, volume={39}, number={1-4}, journal={Integrated Ferroelectrics}, author={Ayguavives, F. and Jin, Z. and Tombak, A. and Maria, J. P. and Mortazawi, A. and Kingon, A. I.}, year={2001}, pages={1343–1352} }
 @article{ayguavives_agius_ea-kim_vickridge_2001, title={Oxygen transport during annealing of Pb(Zr,Ti)O-3 thin films in O-2 gas and its effect on their conductivity}, volume={16}, ISSN={["2044-5326"]}, DOI={10.1557/JMR.2001.0412}, abstractNote={Lead zirconate titanate (PZT) thin films were deposited in a reactive argon/oxygen gas mixture by radio-frequency-magnetron sputtering. The use of a metallic target allows us to control the oxygen incorporation in the PZT thin film and also, using oxygen 18 as a tracer, to study the oxygen diffusion in the thin films. Electrical properties and crystallization were optimized with a 90-nm PZT thin film grown on RuO2 electrodes. These PZT films, annealed with a very modest thermal budget (550 °C) show very low leakage current densities (J = 2 × 10−8 A/cm2 at 1 V). In this article we show that a strong correlation exists between the oxygen composition in the PZT film and the leakage current density.}, number={10}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Ayguavives, F and Agius, B and Ea-Kim, B and Vickridge, I}, year={2001}, month={Oct}, pages={3005–3008} }
 @article{stauf_ragaglia_roeder_vestyck_maria_ayguavives_kingon_mortazawi_tombak_2001, title={Thick electrodes for high frequency high Q tunable ferroelectric thin film varactors}, volume={39}, DOI={10.1080/10584580108011955}, abstractNote={Abstract Thin film barium strontium titanate (BST) shows great promise for voltage tunable dielectric devices for use at RF and microwave frequencies. An MOCVD process has been developed for production of BST, resulting in films with very low losses (as low as 0.002–0.004) and tunabilities over 50% at low operation voltages. With these values of BST loss, overall device quality factors at RF (100 MHz+) frequencies are primarily limited by losses in the thin metal electrodes, such as Pt, normally used for ferroelectric thin films. The bottom electrode in parallel plate capacitor structures is particularly challenging, since it must provide a good growth surface for BST and be stable at high (>600 °C) growth temperatures in an oxidizing atmosphere yet have high conductivity and compatibility with Si or SiO2/Si substrates. These challenges have previously prevented use of Pt thicknesses over 0.1–0.2 urn. Our solution to this problem, involves combinations of adhesion layers at the Pt/SiO2 interface and embedded stabilization layers to make functioning Pt bottom electrodes as thick as 2 μm. Devices with dielectric Q factors over 150 at 100 MHz (tan δ ∼ 0.006 as measured and modeled by S-parameters) and overall device Q factors over 50 at 30 MHz are described. We have also inserted these devices into tunable filters, achieving tunabilities of 50% and low insertion losses (0.3 dB) at RF frequencies.}, number={1-4}, journal={Integrated Ferroelectrics}, author={Stauf, G. T. and Ragaglia, C. and Roeder, J. F. and Vestyck, D. and Maria, J. P. and Ayguavives, T. and Kingon, A. and Mortazawi, A. and Tombak, A.}, year={2001}, pages={1271–1280} }