Characterization of amorphous barium titanate films prepared by rf sputtering

Abstract

The physical and electrical properties of amorphous BaTiO3 films prepared by rf sputtering have been investigated as a function of rf power, substrate temperature and bias, and sputtering gas pressure and composition. A charge storage capacity of ∠0.04 C/m2 was found for films prepared in pure argon on substrates held at near room temperture during deposition. These films showed a dielectric constant of ∠14 with little dependence on frequency or temperature. No evidence for ferroelectric behavior was observed. Inadequate substrate cooling yielded films which had very high dissipation factors and low breakdown strengths. The addition of oxygen to the sputtering gas resulted in films which exhibited a strong temperature coefficient of capacitance which increased at low frequencies. Oxygen additions produced a change in the titanium to barium ratio present in the films and gave rise to increases in the dielectric dissipation factor, the dc conductivity, and the defect density.