Dielectric response of cu/amorphous BaTiO3/Cu capacitors

Cu/amorphous BaTiO3/Cu capacitors were tested for their dielectric properties in the 0.1 Hz-100 kHz range, from room temperature to 350 degrees C. The amorphous barium titanate dielectric layer was deposited by rf sputtering on water-cooled copper electrodes. The room-temperature dielectric constant is around 18 and the dissipation factor is 3x10(-3) at 100 kHz. When increasing temperature the dielectric response displays an important frequency dispersion with the appearance of a marked loss peak at low frequencies. This dispersion is ascribed to electrode polarization effects, as evidenced by measurements performed on various film thicknesses and by using different electrodes. The electrode polarization phenomenon is discussed using a simple space charge model and is shown to be related to mobile oxygen vacancies. (c) 2007 American Institute of Physics.