IMPROVEMENT OF THE DEGRADATION CHARACTERISTICS OF SOL-GEL DERIVED PZT (53/47) THIN FILMS: EFFECT OF CONVENTIONAL AND GRADED IRON DOPING

摘要

Several approaches are evident in the literature to improve the fatigue resistance and lower the leakage current densities of PZT thin films for nonvolatile random access memory (NVRAM) application. We have undertaken an approach of doping (conventional and graded) of PZT (53/47) thin films with Fe cation, which tend to occupy B-site in the ABO_3 unit cell. Our studies indicated several improvements in the electrical characteristics. The graded doped Fe film of similar dopant concentrations exhibited even better fatigue behavior up to approx 10~9 cycles. In addition, the Ohmic behavior in I-V characterization extended up to 250 kV/cm for graded doped films, while the non-linearity sets at much lower field (150kV/cm) for undoped films at room temperature. Conventional doping improved the electrical behavior as compared to undoped films. However, the graded doped films exhibited even further improved electrical behavior in terms of reducing leakage current by at least an order of magnitude under an applied electric fields of about 150 kV/cm.