Preparation and ferroelectric properties of YMnO3 thin films with c-axis preferred orientation by the sol-gel method

Hexagonal YMnO3 has a ferroelectric property with an optimal remanent polar ization along the c-axis. The c-axis oriented YMnO3 thin films with a small leakage current were prepared by the sol-gel dipping method. The c-axis or ientation of the films was promoted by the addition of diethanolamine to th e Mn precursor solution. A heat treatment with multiple steps led to a dens e film structure with fine grains. The dense structure resulted in the decr ease of the leakage current. Furthermore, when the films were heat-treated in a vacuum, the leakage current became considerably small and the ferroele ctricity of the YMnO3 thin films was observed even at room temperature.