Characteristics and Ferroelectric Properties of Pb(Zr, Ti)O3 Capacitors with Pt/La0.5Sr0.5Co1.0O3 Top and La0.5Sr0.5Co1.0O3/SrTiO3/Pt/SrTiO3 Bottom Electrodes

Abstract

Sol-gel-derived Pb(Zr, Ti)O3 films with thin, room temperature sputter-deposited and postannealed Pt/La0.5Sr0.5Co1.0O3 top and La0.5Sr0.5Co1.0O3/SrTiO3/Pt/SrTiO3 bottom electrodes were synthesized on SiO2/Si(100) substrates, and the microstructures and ferroelectric properties were examined. Insertion of SrTiO3 layers with optimum thicknesses in the bottom electrode improved surface roughness of the bottom electrode and the Pb(Zr, Ti)O3 film, and strengthened the adhesion of the bottom electrode to the substrate. The stacking of La0.5Sr0.5Co1.0O3, SrTiO3 and Pt layers in the bottom electrode yielded Pb(Zr, Ti)O3 (40/60) films with flat surfaces; the fatigue tests at 3 V, 100 kH indicated that switchable polarization was greater than 15 µC/cm2, and no fatigue degradation was observed up to 1010 cycles. However, the PZT films with higher Ti concentration in the composition exhibited gradual decay in polariation from fatigue cycles of 106. The possible reason for the decay in polarization was discussed. The leakage current was of the order of 10-5 A/cm2 at driving voltages of 2–3 V; considerable scattering among the leakage current data was observed.