Characteristics of BaTiO3 thin films on Si deposited by rf magnetron sputtering

Thin films of BaTiO3 were deposited on single-crystal Si using rf magentron sputtering. Different microstructures resulted from varying the substrate temperature during sputtering or from post-annealing after film deposition. High trap and surface state densities at the interface between BaTiO3 and Si were found for the films deposited at room temperature even though such films showed a relatively low leakage current and a high breakdown voltage. These surface states or traps, nevertheless, could be partially annealed out of the film at a temperature around 450 degrees C. High deposition temperatures above 600 degrees C introduced unrecoverable surface states at the interface. BaTiO3 thin films that were deposited at a substrate temperature in the range 450-500 degrees C gave the best performance in terms of their electrical and interface properties. BaTiO3 thin-him capacitors with a configuration of Au/BaTiO3/p-Si/Al, fabricated with optimized BaTiO3 thin-him deposition conditions, showed a value of the dielectric constant near 30, a leakage-current density as low as 10(-7) A cm(-2) at a held intensity of 2 x 10(5) V cm(-1), a breakdown voltage above 10(6) V cm(-1) and an interface state density of around (4-6) x 10(11) eV(-1) cm(-2).