Structural and Electrical Properties of (1-x)Bi5Nb3O15-xBi4Ti3O12 Ceramics and 0.96Bi5Nb3O15-0.04Bi4Ti3O12 Thin Films Grown by Pulsed Laser Deposition

A 0.96Bi(5)Nb(3)O(15)-0.04Bi(4)Ti(3)O(12) (0.96B(5)N(3)-0.04B(4)T(3)) ceramic showed a high dielectric constant (k) of 314, probably due to the increased dipole moment caused by the replacement of Nb5+ ions by Ti4+ ions. The 0.96B(5)N(3)-0.04B(4)T(3) films, were well formed on the Pt/Ti/SiO2/Si substrate. Films grown at temperatures lower than 400 degrees C had an amorphous phase but small Bi3NbO7 crystals were considered to have been formed in these. films. The film grown at 300 degrees C exhibited a high k value of 83 with a low dielectric loss of 0.5%. The leakage current density of the film grown at low oxygen pressure (OP) was high and decreased with increasing OP to a minimum at an OP of 200 mTorr, after which it increased with further increase in OP. This variation of the leakage current density with OP was explained by the existence of oxygen vacancies and interstitial oxygen ions in the film. The 0.96B(5)N(3)-0.04B(4)T(3) film 2 grown under 200 mTorr OP exhibited a high k value of 83, a low leakage current density of 8 x 10(-8) A/cm(2) at 0.3 MV/cm and a high breakdown field of 0.4 MV/cm.