Microwave dielectric properties of BaTi4O9 thin film

BaTi4O9 thin films have been prepared by RF magnetron sputtering on the Pt/Ti/SiO2/Si substrates and the dielectric properties of the BaTi4O9 film have been investigated at microwave frequency range. The homogeneous BaTi4O9 thin film was obtained when the film was grown at 550 °C and rapid thermal annealed (RTA) at 900 °C for 3 min. The circular-patch capacitor (CPC) was used to measure the microwave dielectric properties of the film. The dielectric constant (ɛr) and the dielectric loss (tan δ) were successfully measured up to 6 GHz. The ɛr of the BaTi4O9 thin film slightly increased with the increase of the film thickness. However, the tan δ decreased with increasing the thickness of the film. The ɛr of BaTi4O9 thin film was similar to that of the BaTi4O9 ceramics, which is about 36–39. The tan δ of the film with 460 nm thickness was very low approximately, 0.0001 at 1–3 GHz. Since BaTi4O9 film has a high ɛr and a low tan δ, the BaTi4O9 film can be used as the microwave devices.