Microstructural and Electrical Properties of Ferroelectric Capacitors with Pt/RuO2 Hybrid Electrodes

Abstract

ABSTRACTThin films of pb(Zr0.53Ti0.47)O3 (PZT) grown in our laboratory on RuO2 electrodes by the sol-gel process are characterized by high leakage currents and by the presence of a pyrochlore-type second phase. We have used a thin Pt interlayer between the PZT film and RuO2 bottom electrode to produce RuO2/PZT/100ÅPt/RuO2/SiO2/Si capacitor structures. It is found that use of such a Pt interlayer significantly reduces or eliminates the second phase in the PZT films, and lowers their leakage currents by more than four orders of magnitude. At the same time, the excellent resistance to polarization fatigue characteristic of the RuO2/PZT/RuO2 capacitors is maintained. The microstructures of PZT films grown on RuO2 electrodes with and without the 100Å Pt interlayer are compared. In addition, the voltage, temperature, and polarity dependence of the leakage current in these samples was measured. The data suggest that leakage current in these samples is most likely Schottky emission controlled. The barrier heights are determined to be about 0.80 and 0.73 eV for the top and bottom interfaces, respectively.