AgTa_0.5Nb_0.5O₃ THIN FILM MICROWAVE COPLANAR WAVEGUIDE TUNABLE CAPACITORS

ABSTRACT

400 nm thick AgTa_0.5Nb_0.5O₃ (ATN) films have been prepared by pulsed laser deposition technique on LaAlO₃ (001) and sapphire (Al₂O₃-0112, r-cut) single crystal substrates. Comprehensive X-ray diffraction analysis showed epitaxial quality of ATN/LaAlO₃ films and preferentially (001) orientation of ATN/Al₂O₃ films. Voltage tunable microwave capacitors were fabricated by lift-off technique on the surface of ferroelectric films. Microwave on-wafer tests were performed in the range from 1 to 40 GHz. Frequency dispersion is about 4.3%, voltage tunability is 4.7% @ 20 GHz and 200 kV/cm, loss tangent ∼ 0.068 @ 20 GHz, K-factor = tunability/tanδ is ranged from 124% @ 10 GHz to 35% @ 40 GHz.

Keywords:

• Coplanar waveguide
• microwave on-wafer test
• photolithography
• pulsed laser deposition
• scatering parameter measurements
• ferroelectric thin films
• silver tantalate niobates
• voltage tunable device

ACKNOWLEDGMENTS

This research was funded by the Swedish Foundation for Strategic Research (SSF). The authors would like to thank Dr. Gunnar Malm for his microwave measurement assistance.