Factors governing ferroelectric switching characteristics of thin VDF/TrFE copolymer films

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Abstract

A series of ferroelectric switching measurements are performed on the 75/25mol% vinylidene fluoride /trifluoroethylene copolymer thin films with various structures to elucidate the factors governing the switching characteristics of such films. It is shown that the spin-coated and well-annealed samples exhibit a remanent polarization Pr of 85 mC/m2. Unlike that in previous reports, the switching time τs of these samples is independent of thickness down to 50 nm if Au electrodes are used instead of Al electrodes. Thin films with different metal electrodes exhibit anisotropic τs due to a potential difference between metal electrodes produced by their work function difference. A train of unipolar short on-off electric field pulses induce a slow but full polarization reversal whose time evolution supports the nucleation and growth mechanism. Continuous switching under bipolar on-off electric field pulses reveals an accelerated polarization reversal with decreasing pulse width. This means that τs is a function of not only applied electric field but also the preceding poling conditions. Fatigue is significantly improved using Au electrodes instead of Al electrodes. The results are discussed in relation to the microscopic features of the VDF/TrFE copolymer and the underlying nucleation-growth mechanism.

Original languageEnglish
Article number1714938
Pages (from-to)1120-1131
Number of pages12
JournalIEEE Transactions on Dielectrics and Electrical Insulation
Volume13
Issue number5
DOIs
Publication statusPublished - 1 Oct 2006

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Keywords

  • Ferroelectric polymer
  • Nucleation and growth
  • Switching time
  • Thin film
  • VDF/TrFE
  • Vinylidene fluoride

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