Dielectric properties of (Na, K)NbO3 thin films for tunable microwave device application

The (NaxK1-x)NbO3 (NKN) thin films were fabricated by using the alkoxide-based sol-gel method. The NKN stock solution was spin-coated. onto a Pt/Ti/SiO2/Si substrate. The coating and drying procedures were repeated several times to obtain the film thickness of about 200 nm, and then the films were annealed at 550-700 degrees C for 1 h. Structural properties of the NKN thin films were investigated by thermogravimetric analysis/differential scanning calorimetry, field emission scanning electron microscope and X-ray diffraction spectroscopy. The dielectric constant and the dielectric loss for the films sintered at 650 degrees C were found to be 338 and 0.018, respectively. The results show that the NKN thin films are promising candidate for use in tunable devices application.