Preparation of near-1-µm-thick {100}-oriented epitaxial Y-doped HfO2 ferroelectric films on (100)Si substrates by a radio-frequency magnetron sputtering method

Y-doped HfO2 films with various thicknesses were prepared on (100)-oriented [10 wt.% Sn-doped In2O3, ITO]//(100) [yttria-stabilized zirconia, YSZ], and (111)ITO//(111)YSZ substrates by a radio-frequency magnetron sputtering method. Almost a single phase of orthorhombic symmetry was obtained for all films. {100}-oriented epitaxial films were obtained on (100)ITO//(100)YSZ substrates, while the film orientation changed from {111} to {100} with increasing film thickness on (111)ITO//(111)YSZ substrates. {100}-oriented epitaxial Y-doped HfO2 films were also obtained on (100)-oriented epitaxial ITO layers on (100)YSZ//(001)Si substrates. Ferroelectricity was observed for all films. Their remanent polarization (Pr) and coercive fields (Ec) were about 5 µC/cm2 and 1 MV/cm, respectively, indicating that Pr and Ec were almost independent of the film thickness and kind of substrate.