Room-temperature deposition of ferroelectric HfO2-based films by the sputtering method

Ferroelectricity has been demonstrated in epitaxial 7%Y-doped HfO2 (0.07YO1.5–0.93HfO2, YHO7) films grown by the RF magnetron sputtering method at room temperature without any subsequent annealing. The x-ray diffraction patterns of such films suggested that the decrease in RF power and in the partia...

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Bibliographic Details
Published in:Applied physics letters 2020-02, Vol.116 (6)
Main Authors: Mimura, Takanori, Shimizu, Takao, Uchida, Hiroshi, Funakubo, Hiroshi
Format: Article
Language:English
Subjects:
Applied physics
Coercivity
Crystal structure
Crystallization
Crystals
Diffraction patterns
Electric fields
Epitaxy
Ferroelectric materials
Ferroelectricity
Hafnium oxide
Hysteresis loops
Indium tin oxides
Magnetron sputtering
Orthorhombic phase
Polarization
Polyethylene terephthalate
Room temperature
Silicon dioxide
Substrates
Titanium oxides
Yttria-stabilized zirconia
Yttrium oxide
Zirconium dioxide
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Summary:Ferroelectricity has been demonstrated in epitaxial 7%Y-doped HfO2 (0.07YO1.5–0.93HfO2, YHO7) films grown by the RF magnetron sputtering method at room temperature without any subsequent annealing. The x-ray diffraction patterns of such films suggested that the decrease in RF power and in the partial oxygen pressure changes the crystal structures of the films from the monoclinic phase to the tetragonal/orthorhombic phase. Clear polarization-electric-field (P–E) hysteresis loops were observed for these epitaxial films with the tetragonal/orthorhombic phase. The obtained remanent polarization (Pr) and coercive field (Ec) values were 14.5 and 12.8 μC/cm2 and 2300 and 2200 kV/cm for the epitaxial films on (111) indium tin oxide (ITO)//(111) yttria-stabilized zirconia (YSZ) and (100)ITO//(100)YSZ substrates, respectively. Moreover, ferroelectricity was also observed in room-temperature-deposited polycrystalline YHO7 films prepared on Pt/TiOx/SiO2/(100)Si, crystallized ITO/soda glass, and amorphous ITO/polyethylene terephthalate substrates, namely, crystalline ferroelectric HfO2-based films were prepared at room temperature on various substrates, including organic flexible substrates, by using the RF magnetron sputtering method. The present results open a path to novel applications of ferroelectric HfO2-based films such as ferroelectric flexible memory.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.5140612