Domain Structure of Poled Ferroelectric (111) PZT (PbZr0.25Ti0.75O3) Films

Films of (111) oriented self-polarized, tetragonal ferroelectric PZT crystallites on (100)Si/SiO2(250 nm)/(111) Pt (50 nm) have been investigated by STM, AFM and SAXS. After metallization of the PZT surface with a Cr-Ni film (5.2 nm thickness) or a Ti film (5.0 nm thickness), single domains were visible on the metal surface by STM measurements as parallel stripes. The lamellar stripes had a width of 10.5 – 25.2 nm and a vertical corrugation of 0.9 – 3.0 nm at the intersection line of the domain walls with the crystallite surface.High resolution AFM with EBD supertips on unmetallized samples revealed areas of typically several µm in diameter showing crystallites with perfectly parallel aligned (90°) domains of 10 - 15 nm width with their boundaries along {110} planes. Single domain walls were visible as a trace on the surface by a negative corrugation effect of 1.0 – 1.5 nm. This corrugation is assumed to be a reflection of the strain distribution normal to the surface. Furthermore, coherency (oxygen) defects are accumulated at the interface between 90 ° twin domains.SAXS investigations allowed to estimate a mean value of domain thickness of 17.5 nm. Exertion of stress (5.1 104Nm−2) to the film resulted in an increase of domain width by ∼1%.