Study on analysis and applications of patterned ferroelectric materials using PFM

Abstract

Last decades, ferroelectric materials are of significant importance in nonvolatile memories, sensors, and actuator applications. With increasing demand for miniaturization in microelectronics, ferroelectric nanostructures have attracted considerable practical and theoretical interest. However, patterned films generally lead to degraded performance, with higher values of field being required to switch polarization and lower values of remnant polarization being attained. In this study, we investigate the effect of nano/micro patterning on the ferroelectricity of both ferroelectric oxides and ferroelectric polymers using PFM. Ferroelectric oxides were patterned by using e-beam lithography and FIB, and the ferroelectric domain structure was investigated by AR-PFM, which is advanced polarization domain imaging technique. The patterning of thin films to mesa structures can be useful for nanoelectronic applications because of reducing the ferroelectric domain complexity. For ferroelectric polymers, meanwhile, spin coating of the polymer on the patterned substrate was carried out to maximize the alignment without damaging the polymer through a simple process. We analyzed the length and the angle of crystalline lamellae depending on the period of line-patterned substrate and annealing condition. LPFM and VPFM measurements reveal that not only crystalline lamellae, but also polymer chain are well aligned. We believe that, based on above findings, this study will provide enhanced fundamental basis for understanding of patterned ferroelectric materials. Furthermore, the precise ferroelectric domain structures have been investigated using a ferroelectric domain imaging technique, PFM. This study would help us to understand the fundamental analysis of the ferroelectric domain structure and improve the performance of ferroelectric devices using confinement effect of patterning.