Fatigue-free lead zirconate titanate (Pb(Zr,Ti)O-3)-based capacitors co-modified by lanthanum and lithium for nonvolatile memories

Abstract

Pb-0.98(La1-xLix)(0.02)(Zr0.55Ti0.45)O-3 (PLLZT with 0.1 less than or equal to x less than or equal to 0.7) thin films were sol-gel-grown on Pt(111)/Ti/SiO2/Si substrates, employing a thin lead zirconate titanate (PZT) template layer. Films annealed at >550degreesC showed a highly [111]-oriented preferential growth. Typical values of the switchable remanent polarization (2P(r)) and the coercive field (E-c) of the PLLZT/PZT/Pt film capacitor for x = 0.3 were 50 muC/cm(2) and 39 kV/cm, respectively, at 5 V. All the PLLZT/PZT/Pt capacitors (for 0.1 less than or equal to x less than or equal to 0.7) exhibited fatigue-free behavior up to 6.5 x 10(10) switching cycles, a quite stable charge retention profile with time, and high 2P(r) values, all which assure their suitability for nonvolatile ferroelectric memories.