Thermally induced voltage offsets in Pb(Zr,Ti)O3 thin films

Voltage offset in the polarization-voltage characteristics of Pb(Zr,Ti)O-3 (PZT) capacitors was evaluated by a thermal stress process. A thermally induced voltage shift occurs when heating the sample under either remanence or a saturating bias. It was found that the voltage shifts can, to a large extent, be attributed to the role of charged defects and the defect-dipole alignment throughout the films. PZT film with a high Zr/Ti ratio, i.e., rhombohedral compositions exhibited the best imprint resistance. When these films were doped wit up to 6% La, the imprint resistance was further improved. It was also found that B-site donors were more effective in minimizing the voltage shift than A-site donors. However, dopants with the same charge value as Pb, for example, Ca and Sr, did not affect the thermally induced voltage shifts of the films since they could not reduce the charged defects in the films. (C) 2000 American Institute of Physics. [S0003-6951(00)04145-0].