Effects of Sputtering Pressure on the Properties of BaTiO3 Films for High Energy Density Capacitors

Abstract

Flexible BaTiO 3 films as dielectric materials for high energy density capacitors were deposited on polyethylene terephthalate (PET) substrates by r.f. magnetron sputtering. The growth behavior, microstructure and electrical properties of the flexible BaTiO 3 films were dependent on the sputtering pressure during sputtering. The RMS roughness and crystallite size of the BaTiO 3 increased with increasing sputtering pressure. All BaTiO 3 films had an amorphous structure, regardless of the sputtering pressures, due to the low PET substrate temperature. The composition of films showed an atomic ratio (Ba:Ti:O) of 0.9:1.1:3. The electrical properties of the BaTiO 3 films were affected by the microstructure and roughness. The BaTiO 3 films prepared at 100 mTorr exhibited a dielectric constant of ~80 at 1 kHz and a leakage current of 10 −8 A at 400 kV/cm. Also, films showed polarization of 8 µC/cm 2 at 100 kV/cm and remnant polarization (P r ) of 2 µC/cm 2 . This suggests that sputter deposited flexible BaTiO 3 films are a promising dielectric that can be used in high energy density capacitors owing to their high dielectric constant, low leakage current and stable preparation by sputtering.