J. Phys. IV France 11 (2001) Pr11-9-Pr11-19
New interface effects in ferroelectric thin filmsJ.F. Scott and M. Dawber
Symetrix Centre for Ferroics, Earth Sciences Department, Cambridge University, Cambridge CB2 3EQ, U.K.
We discuss four things : First, that for ferroelectric thin films on metal electrodes, terms usually ignored in the calculation of band match-ups (negligible for Si devices) are quite large (ca. 0.5 eV) ; second, for ultra-thin films (ca. 7 nm) much of the voltage drop is inside the metal electrode ; third, that the oxygen vacancy gradient in perovskite oxides can be fitted to bulk and grain boundary diffusion, assumed quenched in at the deposition temperatures ; and fourth, that elemental bismuth at the surfaces of strontium bismuth tantalate (SBT) and other bismuth-compound ferroelectrics is not an artefact but arises from a phase separation and wetting transition of Bi2O3 on SBT grains, similar to that well known in ZnO-Bi2O3 varistors.
© EDP Sciences 2001