An orientation ratio and ferroelectric properties of ultra-thin PTO films

The relationship among crystallographic orientation and quality, flatness of a surface, electrical properties and thickness for lead titanate (PbTiO3: PTO) ultra-thin films is reported. A crystallographic orientation changed from (1 0 0) to (0 0 1) with an increase in film thickness. However, a (0 0 1) plane orientation ratio α saturated to 0.85 and root square mean (RMS) of flatness saturated to 1.4 nm when the film thickness was approximately 90 nm. A PTO film thinner than approximately 90 nm had a larger dielectric constant and that thicker than approximate 90 nm showed ferroelectric property.