| 1. |
- Bonetti, Stefano, et al.
(author)
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Buried tantalate-niobate microwave varactors
- 2007
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In: 2006 15TH IEEE INTERNATIONAL SYMPOSIUM ON APPLICATIONS OF FERROELECTRICS. - 9781424413317 ; , s. 347-350
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Conference paper (peer-reviewed)abstract
- We present characteristics of microwave variable capacitors (varactors) buried in 2.5 mu m thick AgTa0.5Nb0.5O3 (ATN) film pulsed laser deposited on sapphire single crystal. 2 gm gap interdigital capacitors (IDC) were fabricated by photolithographic, dry etching and lift-off processes. For comparison, similar IDCs were also defined on top of ATN film. Capacitance and loss tangent have been determined using a modified de-embedding technique in the microwave range 25 MHz - 40 GHz. Buried structures show higher values of capacitance and tunability, keeping the same level of losses compared to standard topped devices and resulting in an increased K-factor = tunability/tan delta. Experimental results are explained within equivalent circuit model. Besides the increased performance, the new design avoids the need of a successive planarization step, which could be required in an integration process.
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| 2. |
- Kim, Jang-Yong, et al.
(author)
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Microwave properties of AgTa0.5Nb0.5O3 thin film varactors on various substrates
- 2007
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In: 2006 15TH IEEE INTERNATIONAL SYMPOSIUM ON APPLICATIONS OF FERROELECTRICS. - New York : IEEE. - 9781424413317 ; , s. 363-366
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Conference paper (peer-reviewed)abstract
- 400nm thick AgTa0.5Nb0.5O3 (ATN) films have been sintered by pulsed laser deposition technique on LaAlO3 (001), sapphire (Al2O3-01 (1) under bar2, r-cut) single crystal substrates and Coming 7059 Glass. Photolithography and metal lift-off technique were used to fabricate tunable Coplanar Waveguide Interdigital Capacitors (CPWIDCs). On-wafer test of varactors was performed with microwave network analyzer and G-S-G microwave probe. ATN/LaAlO3 capacitors demonstrated the highest tunability (similar to 5.8%@20GHz), ATN/Glass showed the best flat dispersion (similar to 3.9%) and ATN/ Al2O3 showed the lowest loss tangent (similar to 0.06@20GHz) in the microwave range from 1 to 40 GHz.
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