Published online by Cambridge University Press: 01 February 2011
Electric-field-induced displacements of PZT film capacitor Pt/PZT(5μm)/Pt/SiO2/Si(100) were calculated by finite element method with various parameters of sample geometry: the diameter of top electrode φ TE ranging from 0.2 μ m to 1000 μ m and whether PZT film was continuous or side-etched. If φ TE was larger than 40μ m, surface longitudinal displacement (corresponding to AFM-measured strain) was not equal to net longitudinal displacement of PZT film, including a contribution of the bending motion of substrate. In contrast, if φ TE was smaller than 4μ m and PZT film was continuous, effective d 33 evaluated from net longitudinal displacement was smaller than intrinsic d 33, because the side PZT film clamped the edge of the capacitor disk and prevented the whole disk from elongating longitudinally. It was also revealed that d 33 value calculated from net longitudinal displacement of PZT film depended on the Poisson's ratio of PZT and was not equal to intrinsic d 33, excluding the case that φ TE was smaller than 4μ m and PZT film was side-etched. In conclusion, it is suggested that smaller φ TE (< 4μ m, in our case) and side-etch treatment permit a precision measurement of d 33; however this condition is difficult to be satisfied experimentally.