In the microscopic polarization-switching of SrBi2Ta2O9 (SBT) thin films, a
significant proportion of the crystallites have proved to remain unswitcha
ble. From the Curie-rule and from hysteresis measurements of SET material w
ith uniform crystal orientation, it follows that SET posseses only two pola
r axes. The switchable polarization of polycrystalline films with different
numbers of polar axes is simulated numerically. It is shown that SET capac
itors with large-size electrodes may exhibit good switchability. However fo
r high density memory applications, severe microstructural orientation requ
irements must be fulfilled to avoid switching failures. Materials with more
than two polar axes make far reduced or no demands regarding texture quali
ty. (C) 2001 Elsevier Science Ltd. All rights reserved.