Tunneling and fatigue properties of SRO/PZT/Pt structures

Tunneling and fatigue measurements at different temperatures were carried out in capacitor structures based on Pb(Zr$_{0.52}$Ti$_{0.48})$O$_{3}$ (PZT) ferroelectric thin films with bottom electrodes of SrRuO$_{3}$ (SRO) and top electrodes of Platinum (Pt). SRO electrodes were deposited on (100) SrTiO$_{3}$ single crystal substrates using a high oxygen pressure on-axis dc-sputtering technique. PZT films were grown by rf magnetron sputtering in pure oxygen atmosphere. Surface roughness and morphology were studied by atomic force microscopy. Electrical characterization has been realized by P-E hysteresis loops and fatigue measurements. Current-voltage (I-V) characteristics showed a slight hysteretic behavior while the bias voltage dependence of the dynamic conductance measurements presented a parabolic characteristic indicating electron tunneling. I-V curves and conductance measurements also show an asymmetric shape that can be explained by the different work functions at the interfaces. A Brinkman fit of the normalized conductance curves as function of the temperature gives barrier thicknesses below 2 nm.