Preparation of fatigue-free SrBi2Ta2O9 thin firms by rf magnetron sputtering and their ferroelectric properties

摘要

Fatigue-free bismuth-layered SrBi2Ta2O9 (SBT) films were deposited on Pt/Ti/SiO2/Si substrates by r.f. magnetron sputtering at room temperature. The variation of structure and electrical properties were studied as a function of annealing temperatures from 750-850 degrees C. The films annealed at 800 degrees C had a composition ratio of Sr:Br:Ta = 0.7:2.0:2.0. X-ray photoelectron spectroscopy signals of bismuth show an oxygen-deficient state within the SET films. The films annealed at 800 degrees C have a thickness of 200 nm and a relatively dense microstructure. The remanent polarization (2P(r)), and the coercive field (2E(c)), obtained for the SET films, were 9.1 mu C cm(-2) and 85 kV cm(-1) at an applied voltage of 3 V, respectively. The films showed fatigue-free characteristics up to 10(10) cycles under 5V bipolar square pulses. The leakage current density was about 7 x 10(-7) A cm(-2) at 150 kV cm(-1). The SET films prepared by r.f. magnetron sputtering were attractive for application to non-volatile memories. (C) 1998 Kluwer Academic Publishers. [References: 15]