Kiyoshi Nishimura

Ferroelectric hysteresis loop model of imprint properties

In the development of ferroelectric nonvolatile memory, the degradation of data retention is a problem at the time of inversion information recording due to the characteristic degradation observed as the hysteresis curve deformation (imprint) of the ferroelectric material. Previously, the author has proposed a model to represent the hysteresis curve of the ferroelectric with five characteristic constants. Presently, it is shown that the hysteresis curve deformation (imprint) of the ferroelectric can be modeled as a shift of the applied voltage by the internal electric field. In this article, the potential appearing in the bit lines of the ferroelectric memory of 2Tr2C type is investigated with this model so that the mechanism for generating the degradation is presented. In addition, the results of investigation are also presented on the relationship to the internal charge shift as the cause of the hysteresis curve deformation.