Si-Substituted Ultrathin Ferroelectric Films

Solid solutions between Bi2SiO5 and conventional ferroelectric materials such as Bi4Ti3O12, SrBi2Ta2O9 and Pb(Zr,Ti)O3 were formed using a sol-gel spin-coating method. The crystallization temperatures of the films were lower by 150 to 200 C than those of the original ferroelectric films, and the surface of the films became flat and smooth. Because of these excellent properties, ultrathin (13- to 25-nm-thick) ferroelectric capacitors were fabricated, in which the polarization was well saturated at an applied voltage of 0.5 V. Discussion on the formation mechanism of the films is also presented. 10 refs.