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The demonstration of significant ferroelectricity in epitaxial Y-doped HfO 2 film

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ABSTRACT

Ferroelectricity and Curie temperature are demonstrated for epitaxial Y-doped HfO2 film grown on (110) yttrium oxide-stabilized zirconium oxide (YSZ) single crystal using Sn-doped In2O3 (ITO) as bottom electrodes. The XRD measurements for epitaxial film enabled us to investigate its detailed crystal structure including orientations of the film. The ferroelectricity was confirmed by electric displacement filed – electric filed hysteresis measurement, which revealed saturated polarization of 16 μC/cm2. Estimated spontaneous polarization based on the obtained saturation polarization and the crystal structure analysis was 45 μC/cm2. This value is the first experimental estimations of the spontaneous polarization and is in good agreement with the theoretical value from first principle calculation. Curie temperature was also estimated to be about 450 °C. This study strongly suggests that the HfO2-based materials are promising for various ferroelectric applications because of their comparable ferroelectric properties including polarization and Curie temperature to conventional ferroelectric materials together with the reported excellent scalability in thickness and compatibility with practical manufacturing processes.

No MeSH data available.


(a) D–E hysteresis curve of Pt/(YHO-7)/ITO capacitor measured with a triangular electric field at 10 kHz. The insets show schematics of the domains included in the present film. (b) The saturated polarization (Psat; closed squares) and the coercive field (Ec; open circles) as functions of applied field.
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f3: (a) D–E hysteresis curve of Pt/(YHO-7)/ITO capacitor measured with a triangular electric field at 10 kHz. The insets show schematics of the domains included in the present film. (b) The saturated polarization (Psat; closed squares) and the coercive field (Ec; open circles) as functions of applied field.

Mentions: Demonstrating polarization switching accompanied by ferroelectricity in the present film is most crucial. Figure 3(a) shows the D–E hysteresis curves measured for the YHO-7 film on the ITO//(110) YSZ substrate. A relatively high 10 kHz triangular electric field was used for the D–E hysteresis curve measurement to eliminate the effect from leakage current. The hysteresis curves were recorded after applying 100 cycles. These hysteresis curves had square shapes. The slope of the D–E curve near coercive field is still slight even with the epitaxial film. This might be due to the fact that the present film does not have perfect polar axis orientation. Similar example can be found in the study on Pb(Zr, Ti)O3 44. Figure 3(b) shows the saturated polarization and coercive field as functions of the applied electric field. The coercive field as a function of applied field exhibited well-saturated behavior, indicating normal ferroelectric behavior. Also, at the maximum applied field of 5.3 MV/cm, the saturated polarization (Psat) reached to be ~16 μC/cm2.


The demonstration of significant ferroelectricity in epitaxial Y-doped HfO 2 film
(a) D–E hysteresis curve of Pt/(YHO-7)/ITO capacitor measured with a triangular electric field at 10 kHz. The insets show schematics of the domains included in the present film. (b) The saturated polarization (Psat; closed squares) and the coercive field (Ec; open circles) as functions of applied field.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016896&req=5

f3: (a) D–E hysteresis curve of Pt/(YHO-7)/ITO capacitor measured with a triangular electric field at 10 kHz. The insets show schematics of the domains included in the present film. (b) The saturated polarization (Psat; closed squares) and the coercive field (Ec; open circles) as functions of applied field.
Mentions: Demonstrating polarization switching accompanied by ferroelectricity in the present film is most crucial. Figure 3(a) shows the D–E hysteresis curves measured for the YHO-7 film on the ITO//(110) YSZ substrate. A relatively high 10 kHz triangular electric field was used for the D–E hysteresis curve measurement to eliminate the effect from leakage current. The hysteresis curves were recorded after applying 100 cycles. These hysteresis curves had square shapes. The slope of the D–E curve near coercive field is still slight even with the epitaxial film. This might be due to the fact that the present film does not have perfect polar axis orientation. Similar example can be found in the study on Pb(Zr, Ti)O3 44. Figure 3(b) shows the saturated polarization and coercive field as functions of the applied electric field. The coercive field as a function of applied field exhibited well-saturated behavior, indicating normal ferroelectric behavior. Also, at the maximum applied field of 5.3 MV/cm, the saturated polarization (Psat) reached to be ~16 μC/cm2.

View Article: PubMed Central - PubMed

ABSTRACT

Ferroelectricity and Curie temperature are demonstrated for epitaxial Y-doped HfO2 film grown on (110) yttrium oxide-stabilized zirconium oxide (YSZ) single crystal using Sn-doped In2O3 (ITO) as bottom electrodes. The XRD measurements for epitaxial film enabled us to investigate its detailed crystal structure including orientations of the film. The ferroelectricity was confirmed by electric displacement filed – electric filed hysteresis measurement, which revealed saturated polarization of 16 μC/cm2. Estimated spontaneous polarization based on the obtained saturation polarization and the crystal structure analysis was 45 μC/cm2. This value is the first experimental estimations of the spontaneous polarization and is in good agreement with the theoretical value from first principle calculation. Curie temperature was also estimated to be about 450 °C. This study strongly suggests that the HfO2-based materials are promising for various ferroelectric applications because of their comparable ferroelectric properties including polarization and Curie temperature to conventional ferroelectric materials together with the reported excellent scalability in thickness and compatibility with practical manufacturing processes.

No MeSH data available.