Chemical solution deposition of ferroelectric Sr:HfO2 film from inorganic salt precursors

Strontium doped hafnium oxide (Sr:HfO2) ferroelectric thin films with strontium concentrations ranging from 0 to 20mol% were processed with inorganic hafnium source and strontium source using a chemical solution deposition technique. The co-existence of monoclinic phase and ferroelectric orthorhombic phase in the Sr doped HfO2 thin film was confirmed by x-ray diffraction and high-resolution transmission electron microscopy results. The atomic force microscope measurements were adopted and the thin films showed crack-free surface. The intrinsic ferroelectricity of the doped HfO2 thin films could be demonstrated by polarization-voltage hysteresis loops together with piezoelectric force microscope. The maximum twofold remnant polarization value of 3.02 μC/cm2 with a coercive field of 2.0 MV/cm was achieved when the Sr content was 7.5 mol%. Meanwhile, the polarization didn't show obvious degradation until 107 electric cycles, indicating the good fatigue performance of the Sr:HfO2 film. These findings indicate that it is a feasible way to prepare Sr:HfO2 ferroelectric thin films via chemical solution deposition with inorganic salt precursors.