Publications (21) View all
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Conference Proceeding: Effect of the Strain from the Substrate on Tunability of(100) One-axis Oriented (Ba0.5Sr0.5)TiO3 Thin Films
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ABSTRACT: The impact of the residual strain induced by the thermal strain on the dielectric tunability was systematically studied for (100)-one-axis-oriented polycrystalline (Ba<sub>0.5</sub>Sr<sub>0.5</sub>)TiO<sub>3</sub> films. These films were grown on various substrates with different thermal expansion coefficients [a<sub>(sub.)</sub>] covered with a stack of (100)<sub>c</sub>SrRuO<sub>3</sub>/(100) <sub>c</sub>LaNiO<sub>3</sub>/(111)Pt layers. The residual strain was ascertained to linearly increase with the increase in a<sub>(sub.)</sub> by enhancement of the surface-normal lattice spacing of (Ba<sub>0.5</sub>Sr<sub>0.5</sub>)TiO<sub>3</sub> and Pt. Dielectric tunability of the films also linearly increased with the increase in a<sub>(sub.)</sub>. These results clearly demonstrate that dielectric tunability tailoring of the (Ba<sub>0.5</sub>Sr<sub>0.5</sub>)TiO<sub>3</sub> films can be achieved by using residual thermal strain.Applications of Ferroelectrics, 2007. ISAF 2007. Sixteenth IEEE International Symposium on; 06/2007 -
Conference Proceeding: Nonlinear response of BaxSr1 - xTiO3 planar and parallel-plate capacitors to microwave power: comparative study of power handling capability
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ABSTRACT: The power handling capability of tunable microwave devices employing planar and parallel-plate Ba<sub>x</sub>Sri<sub>1- x</sub>TiO<sub>3</sub> film-based capacitors was experimentally measured and analyzed. A microstrip resonator, excited by either harmonic or two-tone microwave signals of elevated power, was selected as an example of tunable test fixture.Microwave Conference, 2005 European; 11/2005 -
Article: Microwave Properties of Parallel Plate Capacitors based on (Ba,Sr)TiO3 Thin Films Grown on SiO2/Al2O3 Substrates
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ABSTRACT: Ba0.7Sr0.3TiO3 (BST) single and quadruple layer capacitors with Pt electrodes were fabricated together on polycrystalline alumina substrates with a SiO2-based multicomponent amorphous buffer layer (SiO2/Al2O3). This paper presents the results of the characterization of these capacitors, to demonstrate their suitability for application as decoupling (high value) capacitors and as components in tunable RF applications (e.g., phase shifters and filters). BST films of different compositions, (Ba0.7Sr0.3)TiO3 and (Ba0.5Sr0.5)TiO3, were grown by metal-organic decomposition (MOD) and RF magnetron reactive sputtering. The capacitance density of 90–140 nm thick BST films was in the range of 20 to 70 fF/μm 2. Parallel plate capacitors with areas from 16 μm2 to 2.25 mm2 were fabricated using photolithography and ion milling techniques. For large capacitors (0.125 to 2.25 mm2), capacitance and tanδ were measured at low frequencies (1 KHz - 1 MHz) using an LCR meter. Smaller capacitors (16 μm2 to 3600 μm2) were additionally characterized in the frequency range of 50 MHz - 20 GHz. In such case, capacitance, tanδ and equivalent series resistance (ESR) were extracted from two port scattering parameters obtained using a vector network analyzer (VNA). The relationship between dielectric loss, tunability and calculated figure of merit vs. BST composition and deposition temperature was outlined. In addition, loss and ESR at high frequencies was investigated. The typical achieved leakage current density of sputtered BST films for 2.25 mm2 capacitors fabricated on SiO2/Al2O3 was 7.3×10-9 A/cm2 at 300 kV/cm (65 fF/μm2), about 2 times lower than for (Ba0.7Sr0.3)TiO3 films deposited by MOD (1.4×10-8 A/cm2 at 300 kV/cm, 34.5 fF/μm2). Furthermore, the tunability of (Ba0.7Sr0.3)TiO3 deposited by both methods on SiO2/Al2O3 was ∼60% at 350 kV/cm.MRS Proceedings. 12/2002; 784. -
Conference Proceeding: Microwave properties of parallel plate capacitors based on (Ba,Sr)TiO 3 thin films grown on SiO2Al2O3 substrates
Materials Research Society Symposium - Proceedings; -
Conference Proceeding: Dielectric properties of (Ba,Sr)TiO3 thin film capacitors fabricated on alumina substrates
Materials Research Society Symposium - Proceedings;
