Size-driven phase transition in stress-induced ferroelectric thin films

We have developed a concise phenomenological theory to investigate phase tr ansitions and dielectric properties of ferroelectric thin films under stres s. When the polarization at the surface is greater than that in the interio r of the film, competition between the 'superpolarized' surface and tensile stress leads to a ferroelectric-paraelectric transition above a critical s tress. This model is appropriate for the data on stress-induced barium-stro ntium titanate (BST) thin-film ferroelectric memory devices [Jpn. J. Appl. Phys. 36 (1997) 5846]. Stress-thickness phase diagrams are presented for Pb TiO3 and BaTiO3 ferroelectric thin films. (C) 2001 Published by Elsevier Sc ience Ltd.