Dielectric and Ferroelectric Properties of Sol-Gel Derived YMnO₃ Films

There has been considerable interest in ferroelectric (FE) films especially for non-volatile memories and ultra high density DRAM applications. Such FE films typically consist of lead zirconate titanate (PZT) with novel oxide contacts, or layered perovskite such as Sr₂Bi₂TaO₉. Recently, there have been reports of sputtered YMnO₃ films which exhibit a single polarization axis and do not contain any volatile species of Pb or Bi. Single crystal YMnO₃ exhibits satisfactory polarization (6 γC/cm²) and low coercive field (<20 kV/cm). Additionally, the dielectric constant of YMnO₃ is quite low (<30) which should facilitate ferroelectric switching. In this study, sol-gel derived YMnO₃ films were prepared on platinized Si wafers and their dielectric and ferroelectric properties were characterized. Their electrical properties will be discussed with respect to Y/Mn stoichiometry ratio, hexagonal phase development and processing conditions. The potential of YMnO₃ as a material in non-volatile memories is evaluated.