Journal of the Korean Applied Science and Technology (한국응용과학기술학회지)

The Korean Society of Applied Science and Technology (한국응용과학기술학회)
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Frequency Characteristics of Coercive Field in Ferroelectric Poly(Vinylidene Fluoride-Trifluoroethylene) Thin Film

강유전성 폴리(비닐리덴 플로라이드-트리플로로에틸렌) 박막의 항전계의 주파수 특성 분석

  • Zhang, Ting (Department of Electronic Engineering, Jeju National University) ;
  • Rahman, Sheik Abdur (Department of Electronic Engineering, Jeju National University) ;
  • Khan, Shenawar Ali (Department of Electronic Engineering, Jeju National University) ;
  • Lee, Kwang-Man (Department of Electronic Engineering, Jeju National University) ;
  • Kim, Woo Young (Department of Electronic Engineering, Jeju National University)
  • Received : 2018.11.30
  • Accepted : 2018.12.21
  • Published : 2018.12.31
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Abstract

In this study, the polarization reversal characteristics of thin film capacitors with a thickness of 100 nm or less fabricated with ferroelectric polymer were measured and analyzed. For the fixed film thickness, polarization reversal occurred at higher coercive fields as the applied maximum electric field increased. For the fixed maximum electric field, polarization reversal occurred at the same coercive field irrespective of the thickness of the thin film. The proportional constant values between the logarithmic electric field and the logarithmic scale frequency were $0.12{\pm}0.01$ for all measurements. As a result, the ferroelectric polymer capacitors consistently exhibited polarization reversal characteristics without any size effects up to a thickness of 40 nm. This study shows the possibility of a polymer memory device that can operate at low voltage, which is useful for predicting the behavior of a low-voltage operating polymer memory device.

본 연구에서는 강유전성 고분자를 이용하여 제작된 100 nm 이하 두께를 가지는 박막형 커페시터의 측정 주파수에 따른 분극 반전 특성을 측정, 분석하였다. 고정된 박막 두께에 대해, 인가되는 최고 전기장의 세기가 증가할수록 더 높은 항전계에서 분극 반전이 발생되었다. 고정된 최고 전기장에 대해, 박막의 두께에 무관하게 같은 항전계에서 분극 반전이 발생되었다. 모든 측정에서 로그스케일 전기장 및 로그스케일 주파수의 관계에서 약 $0.12{\pm}0.01$의 비례 상수를 보였다. 결과적으로, 강유전체 고분자 커페시터가 40 nm 두께까지는 size effect 없이 일정한 분극 반전 특성을 보였다. 본 연구는 저전압 동작 고분자 메모리 소자의 동작 예측에 유용할 것이므로 저전압에서 동작 가능한 고분자 메모리 소자의 가능성을 보여준다.

Keywords

HGOHBI_2018_v35n4_1206_f0001.png 이미지

Fig. 1. Schematic diagram of triangular pulse shapes used for hysteresis loop measurements. E, T, and f mean the electric field, pulse period, and its corresponding frequency, respectively.

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Fig. 2. Surface morphology of ferroelectric film measured with AFM. The measurement were performed by tapping mode in the area of 1 μm × 1 μm (256 × 256 pixels) using NanoMan of Vecco Instruments, Inc.

HGOHBI_2018_v35n4_1206_f0003.png 이미지

Fig. 3. Displacement-electric field (D-E) hysteresis loops for different thickness values. The unit of thickness is nanometer. EMAX, T and f are 1.33 MV/cm, 16 ms and 62 Hz, respectively.

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Fig. 4. Relationships between remanent polarization and film thickness.

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Fig. 5. Coercive voltage-frequency relationships for different EMAX values. The film thickness is 90 nm.

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Fig. 6. Coercive voltage-frequency relationships for different thickness and EMAX values. For each thickness, three kinds of EMAX values were used except the case of 120 nm. Frequency range is from 25 Hz to 260 Hz.

HGOHBI_2018_v35n4_1206_f0007.png 이미지

Fig. 7. Coercive field-frequency relationships for different thickness and EMAX values. For each thickness, three kinds of EMAX values were used except the case of 120 nm. Frequency range is from 25 Hz to 260 Hz.

Table 1. Fitting parameters extracted from coercive voltage-frequency relationships

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References

  1. H. S. Nalwa, Ferroelectric Polymers. p.669-880, Marcel Dekker, Inc. (1995).
  2. J. F. Scott, Ferroelectric Memories. p.179-192, Springer (2000).
  3. K. Uchino, Ferroelectric Devices. p.131-220, Marcel Dekker. Inc. (2000).
  4. G.-X. Ni, Y. Zheng, S. Bae, C. Y. Tan, O. Kahya, J. Wu, B. H. Hong, K. Yao, B. Ozyilmaz, "Graphene-Ferroelectric Hybrid Structure for Flexible Transparent Electrodes", ACS Nano, Vol.6, No.5, pp.3935-3942, (2012). https://doi.org/10.1021/nn3010137
  5. W. Y. Kim, H.-D. Kim, T.-T. Kim, H.-S. Park, K. Lee, H. J. Choi, S. H. Lee, J. Son, N. Park, B. Min, "Graphene-ferroelectric metadevices for nonvolatile memory and reconfigurable logic-gate operations", Nat. Commun., Vol.7, 10429, (2016). https://doi.org/10.1038/ncomms10429
  6. T. N. Jackson, "Beyond Moore's Law", Nat. Mater., Vol.4, pp.581-582, (2005). https://doi.org/10.1038/nmat1444
  7. S. Horiuchi, Y. Tokura, "Organic ferroelectrics", Nat. Mater., Vol.7, pp.357-366, (2008). https://doi.org/10.1038/nmat2137
  8. R. C. G. Naber, K. Asadi, P. W. M. Blom, D. M. de Leeuw, B. de Boer, "Organic Nonvolatile Memory Devices Based on Ferroelectricity", Adv. Mater., Vol.22, pp.933-945, (2010). https://doi.org/10.1002/adma.200900759
  9. R. C. G. Naber, M. Mulder, B. de Boer, P. W. M. Blom, D. M. de Leeuw, "High charge density and mobility in poly(3-hexylthiophene) using a polarizable gate dielectric", Org. Electron., Vol.7, pp.132-136, (2006). https://doi.org/10.1016/j.orgel.2005.11.007
  10. S. Fujisaki, H. Ishiwara, Y. Fujisaki, "Low-voltage operation of ferroelectric poly(vinylidene fluoridetrifluoroethylene) copolymer capacitors and metal-ferroelectricinsulator-semiconductor diodes", Appl. Phys. Lett., Vol.90, 162902, (2007). https://doi.org/10.1063/1.2723678
  11. W. J. Hu, D.-M. Juo, L. You, J. Wang, Y.-C. Chen, Y.-H. Chu, T. Wu, "Universal Ferroelectric Switching Dynamics of Vinylidene Fluoride-trifluoroethylene Copolymer Films", Sci. Rep., Vol.4, 4772, (2014).
  12. T. Nakajima, R. Abe, Y. Takahashi, T. Furukawa, "Intrinsic Switching Characteristics of Ferroelectric Ultrathin Vinylidene Fluoride/Trifluoroethylene Copolymer Films Revealed Using Au Electrode", Jpn. J. Appl. Phys., Vol.44, L1385, (2005). https://doi.org/10.1143/JJAP.44.L1385
  13. N. Inoue, Y. Hayashi, "Effect of Imprint on Operation and Reliability of Ferroelectric Random Access Memory (FeRAM)", IEEE Trans. Electron Devices, Vol.48, pp.2266-2272, (2001). https://doi.org/10.1109/16.954465
  14. Y. W. So, D. J. Kim, T. W. Noh, J.-G. Yoon, T. K. Song, "Polarization switching kinetics of epitaxial $Pb(Zr_{0.4}Ti_{0.6})O_3$ thin films", Appl. Phys. Lett., Vol.86, 092905, (2005). https://doi.org/10.1063/1.1870126
  15. S. M. Yang, J. Y. Jo, T. H. Kim, J.-G. Yoon, T. K. Song, H. N. Lee, Z. Marton, S. Park, Y. Jo, T. W. Noh, "AC dynamics of ferroelectric domains from an investigation of the frequency dependence of hysteresis loops", Phys. Rev. B, Vol.82, 174125, (2010). https://doi.org/10.1103/PhysRevB.82.174125
  16. J. Karthik, A. R. Damodaran, L. W. Martin, "Epitaxial Ferroelectric Hetero-structures Fabricated by Selective Area Epitaxy of SrRuO3 Using an MgO Mask", Adv. Mater., Vol.24, pp.1610-1615, (2012). https://doi.org/10.1002/adma.201104697