Crystallization of amorphous (Pb, La) (Zr, Ti) O3 thin film and its electrical properties

Dense amorphous PLZT films with composition (Pb9.925La0.075) (Zr0.4La0.6) O-3 were deposited on Pt/MgO (100) substrates by rf-magnetron sputtering without heating the substrates and were subsequently crystallized by postdeposition annealing. The optimum conditions in the two-step annealing process to crystallize the amorphous PLZT films were investigated. The post-deposition-annealed films showed excellent crystallinity and c-axis orientation when the amorphous PLZT films were annealed in an oxygen flow at a soaking temperature for the initial nucleation process of T-1=300 degreesC, a temperature for crystal growth process of T-2=750 degreesC, and the T-2-soaking time of t(2)=60 min. Conventional Pt/PLZT/Pt capacitors were fabricated by forming Pt top electrodes on crystallized 300-nm-thick PLZT films. The remanent polarization and the coercive field of the present capacitors, which indicated almost symmetric P-E hysteresis loops, were 2P(r)=30 muC/cm(2) and 2E(c)=90 kV/cm, respectively. The high-endurance PLZT capacitors with excellent ferroelectric properties produced by the present optimized crystallization have great potential for application to nonvolatile memory devices.