Coercive fields in ultrathin BaTiO3 capacitors

Thickness-dependence of coercive field (E-C) was investigated in ultrathin BaTiO3 capacitors with thicknesses (d) between 30 and 5.0 nm. The E-C appears nearly independent of d below 15 nm, and decreases slowly as d increases above 15 nm. This behavior can be explained not by effects of interfacial passive layers or strain relaxation, but by domain nuclei formation models. Based on domain nuclei formation models, the observed E-C behavior is explainable via a quantitative level. A crossover of domain shape from a half-prolate spheroid to a cylinder is also suggested at d similar to 15 nm, exhibiting good agreement with experimental results. (c) 2006 American Institute of Physics.