  Structural studies on ultrathin SrRuO3/BaTiO3/SrRuO3 capacitors, with BaTiO3
thicknesses of between 5 nm and 30 nm, show well-defined interfaces between
ferroelectric BaTiO3 and electrode SrRuO3 layers. In these capacitors, we
cannot observe any extrinsic electrical effects due to either the formation of
an insulating interfacial passive layer or passive-layer-induced charge
injection. Such high quality interfaces result in very good fatigue endurance,
even for the 5 nm thick BaTiO3 capacitor.
