Ferroelectric properties of epitaxial PbZr$_{0.3}$Ti$_{0.7}$O$_{3}$ thin films as a function of SrRuO$_{3}$ electrode thickness

For the past few years, the one of the main research themes in ferroelectrics is the size effect that should be definitely required for miniaturization of the unit cell in FRAM. Until now, most related researches on the ferroelectric thin film have been merely focused on reducing the film thickness and their lateral size, not the electrode. Changing the point of view to the size effect of electrode, we tried to investigate the bottom electrode thickness-dependent ferroelectric characteristic especially focusing on the coercive field. Epitaxial SrRuO$_{3}$ (SRO) films are successfully grown on TiO$_{2}$ terminated SrTiO$_{3}$ surface by using pulsed laser deposition method, while the PbZr$_{0.3}$Ti$_{0.7}$O$_{3}$ (PZT) (also epitaxially grown) thickness was fixed. It is found that the coercive field of the PZT thin film increases as the SRO electrode thickness decreases. Based on this result, we believe that the depolarization field must be strongly coupled to the electrode thickness.