Thickness-dependent dielectric constants of (Ba,Sr)TiO[sub 3] thin films with Pt or conducting oxide electrodes.

The decrease in the measured dielectric constant of sputter-deposited (Ba, Sr)TiO[sub 3] thin films having Pt electrodes with decreasing dielectric film thickness was analyzed by a combination of theories regarding the finite charge-screening length of the metal electrode and the intrinsic-dead layer of the dielectric surface. It was found that the decreasing dielectric constant was mainly due to the metal electrode capacitance rather than the intrinsic-dead-layer capacitance. The almost film-thickness-independent dielectric constant of the (Ba, Sr)TiO[sub 3] thin films with conducting oxide electrodes, IrO[sub 2] and SrRuO[sub 3], when the dielectric film thickness >20 nm, was attributed to the very high capacitance values of the charge-screening layer of the oxide electrodes. The very high capacitance value appeared to originate from the strain-induced high dielectric constant of the oxide electrodes. [ABSTRACT FROM AUTHOR]