IMPRINT IN FERROELECTRIC CAPACITORS

We show that voltage offsets in the characteristics-voltage characteri stics of Pb(Zr,Ti)O-3 capacitors can lead to imprint in ferroelectric memory devices. The thermal-induced voltage shifts (internal bias fiel d) are in part attributed to the role of oxygen vacancy-related defect dipoles throughout the film. In support of this, it is found that don or doping at the Ti(Zr) sites reduces the thermally-induced voltage sh ifts. The stress-induced voltage shifts are found to be dependent on t he Zr/Ti cation ratio. This compositional dependence is explained by c onsidering the role of deep bulk Ti3+ centers and/or a compositional d ependent oxygen vacancy density.