Dielectric properties of KTN(80/20) thin films with pzt buffer layer for tunable microwave devices

Abstract

K(Ta0.80Nb0.20)O-3 films with Pb(Zr0.52Ti0.48)O-3 PZT buffer layer on Pt/Ti/SiO2/Si substrate were fabricated by sol-gel and spincoating method. Structural and electrical properties were measured with variation of the sintering temperature, and the applicability to microwave materials was investigated. All K(Ta0.80Nb0.20)O-3 films showed a cubic crystal structure. Average grain size was about 123 similar to 493 nm and average thickness of the K(Ta0.80Nb0.20)O-3 films was approximately 366 nm. Through the AFM results, root mean square roughness (R-rms) of all K(Ta0.80Nb0.20)O-3 films was around 6 nm. All K(Ta0.80Nb0.20)O-3 films showed a tendency to increase dielectric loss as frequency increased. As the sintering temperature increased, tunability with an applied DC voltage indicated a decreasing tendency. Tunability and temperature coefficient of the K(Ta0.80Nb0.20)O-3 film sintered at 700 degrees C showed good values of 22.1% at 10 V, -0.5941 degrees C.