Stability Analysis of Domains in Ferroelectric Thin Films

Ferroelectric domain switching under low voltage or short pulses is of interest to the development of high-density random access memory (FRAM) devices. Being necessarily very small in size, instability and back switching often occurs when the external voltage is removed, and creates serious problems. In this investigation, a general approach to determine the minimum size of ferroelectric domain to avoid back switching was developed. As examples, two cases were considered in detail: one is a 180 o domain in a ferroelectric thin film covered by the upper and lower electrodes, the other is a 180 o domain in a ferroelectric thin film induced by AFM without the top electrode. We note that our approach is generally applicable to many other fields, including phase transformation, nucleation and expansion of dislocation loops in thin films.