Fabrication and structural characterization of bismuth niobate thin films grown by chemical solution deposition

Abstract

Bi3NbO7 (BNO) thin films were deposited on Pt/TiO2/SiO2/Si (100) substrates at room temperature from the polymeric precursor method. X-ray powder diffraction and transmission electron microscopy were used to investigate the formation characteristics and stability range of the tetragonal modification of a fluorite-type solid solution. The results showed that this tetragonal, commensurately modulated phase forms through the intermediate formation of the incommensurately modulated cubic fluorite phase followed by the incommensurate-commensurate transformation. The 200 nm thick BNO films exhibit crystalline structure, a dielectric constant of 170, capacitance density of 200 nF/cm2, dielectric loss of 0.4 % at 1 MHz, and a leakage current density of approximately 1 × 10−7 A/cm2 at 5 V. They show breakdown strength of about 0.25 MV/cm. The leakage mechanism of BNO film in high field conduction is well explained by the Schottky and Poole–Frenkel emission models. The 200 nm thick BNO film is suitable for embedded decoupling capacitor applications directly on a printed circuit board.