Novel ferroelectric capacitor for non-volatile memory storage and biomedical tactile sensor applications

We report on novel ferroelectric thin film compositions for use in non-volatile memory storage and biomedical tactile sensor applications. The lead zirconate titanate (PZT) composition was modified by lanthanum (La3+) (PLZT) and vanadium (V5+) (PZTV, PLZTV) doping. Hybrid films with PZTV and PLZTV as top layers are also made using seed layers of differing compositions using sol-gel and spin coating methods. La3+ doping decreased the coercive field, polarization and leakage current, while increasing the relative permittivity. V5+ doping, while having similar effects, results in an enhanced polarization, with comparable dielectric loss characteristics. Complex doping of both La3+ and V5+ in PLZTV, while reducing the polarization relative to PZTV, significantly decreases the coercive field. Hybrid films have a greater uniformity of grain formation than non-hybrid films, thus decreasing the coercive field, leakage current and polarization fatigue while increasing the relative permittivity. Analysis using X-ray diffraction (XRD) verified the retention of the PZT perovskite structure in the novel films. PLZT/PZTV has been identified as an optimal ferroelectric film composition due to its desirable ferroelectric, fatigue and dielectric properties, including the highest observed remnant polarization (P-r) of similar to 25 mu C/cm(2), saturation polarization (P-sat) of similar to 58 mu C/cm(2) and low coercive field (E-c) of similar to 60 kV/cm at an applied field of similar to 1000 kV/cm, as well as a low leakage current density of similar to 10(-5) A/cm(2) at 500 kV/cm and fatigue resistance of up to similar to 10(10) switching cycles. (C) 2010 Elsevier B.V. All rights reserved.