Sr 1−x TiO 3 / Cu parallel-plate structure have been fabricated using a layer transfer method. The use of a Cu bottom electrode results in a giant electrode Q-factor ϫ capacitor area product of Q elec A = 3.79ϫ 10 5 m 2 at 1 GHz. The dielectric constant at room temperature is 420 and the tunability amounts to 73% near a breakdown voltage of 35 V. The major advantages of the layer transfer method include low electrode losses, the freedom to select an auxiliary substrate and seed layer for ferroelectric film growth irrespective of their high-frequency properties, and the possibility to utilize a large variety of device substrates as they no longer act as template for film growth.

No abstract

No abstract

Tunable bandstop resonators and filters are fabricated and measured. Lead strontium titanate (PST-Pb 0.4 Sr 0.6 (Ti 1-x Mn x )O 3 ) thin film on a high-resistivity Si substrate is used for an application of low loss tunable circuits at microwave frequency band. Parallel plated PST varactors tune resonators and 3-pole bandstop filters which resonate at the center frequency of 4.23 and 7.1 GHz and its maximum rejection is more than 13.8 dB at the stop band while the insertion loss at the pass band is less than 3 dB.

In pursuit of thin film ferroelectric materials for frequency agile applications that are both easily adapted to large area deposition and also high performance, an investigation has been carried out into sol-gel deposition of 3% Mn doped ͑Pb 0.4 Sr 0.6 ͒TiO 3 . Large area capability has been demonstrated by growth of films with good crystallinity and grain structure on 4 in. Si wafers. Metal-insulator-metal capacitors have also been fabricated and development of an improved de-embedding technique that takes parasitic impedances fully into account has enabled accurate extraction of the high frequency dielectric properties of the Pb x Sr 1−x TiO 3 films. Practically useful values of ϳ 1000, tan ␦ ϳ 0.03, and tunability ϳ50% have been obtained in the low gigahertz range ͑1-5 GHz͒. Peaks in the dielectric loss due to acoustic resonance have been modeled and tentatively identified as due to an electrostrictive effect with an electromechanical coupling coefficient of ϳ0.04 at an electric field of 240 kV/cm which is potentially useful for tunable thin film bulk acoustic wave devices.