Control of leakage conduction of high-fatigue-endurance (Pb, La)(Zr, Ti)O3 film ferroelectric capacitors with Pt/SrRuO3 electrodes

Leakage conduction of (Pb, La)(Zr, Ti)O-3 (PLZT) films grown on Pt bottom electrode, with Pt and Pt/SrRuO3 (Pt/SRO) top electrodes is studied. It is found that the conduction behavior of the ferroelectric capacitors strongly varies depending on the degree of interdiffusion from the electrode into the ferroelectric material. If the diffusion is limited, the conduction properties of the Pt/SRO/PLZT/Pt capacitor are similar to that of the conventional Pt/PLZT/Pt system. For the opposite case of excessive interdiffusion, the former exhibits much higher conduction than the latter. We found that the diffusion of the top electrode material can be controlled in two ways-either by varying Pb excess in the PLZT film or by controlling the SRO layer thickness. Schottky barrier measurements show that in the case of limited diffusion the potential barrier values of SRO/PLZT and Pt/PLZT interfaces are nearly equal. Based on our results we conclude that: (a) the Schottky barrier values of Pt/PLZT and SRO/PLZT contacts are similar and mainly controlled by Fermi level pinning at the interface rather than by work functions of electrode materials; (b) the leakage conduction of Pt/SRO/PLZT/Pt capacitors can be efficiently suppressed without losing good polarization fatigue performance. (C) 1999 American Institute of Physics. [S0003-6951(99)02038-0].