VOLTAGE SHIFTS AND IMPRINT IN FERROELECTRIC CAPACITORS

Voltage offsets in the polarization-voltage characteristics of Pb(Zr,Ti)O-3 capacitors can be induced by either thermal or optical processes. The thermally (optically) induced voltage shift occurs by heating (illuminating) the sample under remanence or a saturating bias. Generally speaking, the thermally induced voltage shifts are greater than those obtained optically; this is attributed to the role of oxygen vacancy-related defect dipoles throughout the film. We find that the inclusion of a dopant element that occupies a portion of the Ti(Zr) sites and has an oxidation state greater than +4 reduces the thermally induced voltage shifts observed in the capacitors. This may result because these particular dopants reduce the oxygen vacancy density and, hence, the defect-dipole contribution to the voltage shift. (C) 1995 American Institute of Physics.