Air stable cross-linked cytop ultrathin gate dielectric for high yield low-voltage top-gate organic field-effect transistors

Xiaoyang Cheng, Mario Caironi, Yong Young Noh, Jianpu Wang, Christopher Newman, He Yan, Antonio Facchetti*, Henning Sirringhaus

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

134 Scopus citations

Abstract

Wedemonstrate the use of a cross-linking chemistry for an amorphous fluoropolymer gate dielectric, poly(perfluorobutenylvinylether) commercially known as Cytop. Spin-coated films of Cytop exhibit good gate insulating properties as well as provide excellentOFET operational stability.However, these devices operate at large voltages because the dielectric layer thickness is typically ∼450-600 nm.When the thickness of a Cytop dielectric layer is decreased below 200 nm, the device yields are dramatically reduced due to pinhole formation. Our new cross-linked Cytop (C-Cytop) formulation deposited by spin-coating enables uniform thin films on top of various organic semiconductors that exhibits lowgate leakage current densities (<10 nA mm-2) and high dielectric breakdown strengths (>2 MV cm-1). Our approach results in C-Cytop dielectric films as thin as 50 nm, thus allowing the fabrication of reliable p- and n-channel top-gateOFETs operating at very low-voltages (<5 V).Themost remarkable properties of this new C-Cytop gate dielectric are the excellent device yields (∼100%) for thicknesses <100 nm and the dramatically reduced sensitivity to the underlying semiconductor film morphology. This new approach represents a significant advance compared to cross-linked PMMA films (C-PMMA) and other nonfluorinated polymer dielectrics on identical test structures. Furthermore, C-Cytop-based OFETs exhibit reduced bias stress and better air stability with respect to C-PMMA because of the inert perfluorinated chemical structure of this polymer. Finally, direct spectroscopic evidence of the cross-linking processwas obtained by Fourier transform infrared (FTIR) spectroscopy, demonstrating complete reaction in air and at room temperature.

Original languageEnglish (US)
Pages (from-to)1559-1566
Number of pages8
JournalChemistry of Materials
Volume22
Issue number4
DOIs
StatePublished - Feb 23 2010

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Materials Chemistry

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