Polarity Effects of Polymer Gate Electrets on Non-Volatile Organic Field-Effect Transistor Memory

Authors

  • Kang-Jun Baeg,

    1. Department of Materials Science and Engineering, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology (GIST) 261 Cheomdan-gwagiro (Oryong-dong), Buk-gu, Gwangju 500-712 (Republic of Korea)
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  • Yong-Young Noh,

    Corresponding author
    1. Convergence Components & Materials Laboratory, Electronics and Telecommunications Research Institute (ETRI), 138 Gajeongno, Yuseong-gu, Daejeon 305-350 (Republic of Korea)
    • Convergence Components & Materials Laboratory, Electronics and Telecommunications Research Institute (ETRI), 138 Gajeongno, Yuseong-gu, Daejeon 305-350 (Republic of Korea).
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  • Jieun Ghim,

    1. Department of Materials Science and Engineering, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology (GIST) 261 Cheomdan-gwagiro (Oryong-dong), Buk-gu, Gwangju 500-712 (Republic of Korea)
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  • Bogyu Lim,

    1. Department of Materials Science and Engineering, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology (GIST) 261 Cheomdan-gwagiro (Oryong-dong), Buk-gu, Gwangju 500-712 (Republic of Korea)
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  • Dong-Yu Kim

    Corresponding author
    1. Department of Materials Science and Engineering, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology (GIST) 261 Cheomdan-gwagiro (Oryong-dong), Buk-gu, Gwangju 500-712 (Republic of Korea)
    • Department of Materials Science and Engineering, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology (GIST) 261 Cheomdan-gwagiro (Oryong-dong), Buk-gu, Gwangju 500-712 (Republic of Korea).
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  • This work was financially supported by the Ministry of Education, Science and Technology (MEST) of Korea through the Brain Korea 21 (BK21) program, the National Research Laboratory (NRL) Program of Korea Science and Engineering Foundation (KOSEF), a grant (F0004021) from the Information Display R&D Center, one of the 21st Century Frontier R&D Programs funded by the Ministry of Knowledge Economy (MKE, 2008-F052-01, Development of Next Generation RFID Technology for Item Level Applications), and the Program for Integrated Molecular Systems (PIMS), at GIST. Supporting Information is available online from Wiley InterScience or from the author.

Abstract

Organic non-volatile memory (ONVM) based on pentacene field-effect transistors (FETs) has been fabricated using various chargeable thin polymer gate dielectrics—termed electrets—onto silicon oxide insulating layers. The overall transfer curve of organic FETs is significantly shifted in both positive and negative directions and the shifts in threshold voltage (VTh) can be systemically and reversibly controlled via relatively brief application of the appropriate external gate bias. The shifted transfer curve is stable for a relatively long time—more than 105 s. However, this significant reversible shift in VTh is evident only in OFETs with non-polar and hydrophobic polymer electret layers. Moreover, the magnitude of the memory window in this device is inversely proportional to the hydrophilicity (determined from the water contact angle) and dielectric polarity (determined from the dielectric constant), respectively. Memory behaviors of ONVM originate from charge storage in polymer gate electret layers. Therefore, the small shifts in VTh in ONVM with hydrophilic and polar polymers may be due to very rapid dissipation of transferred charges through the conductive channels which form from dipoles, residual moisture, or ions in the polymer electret layers. It is verified that the surface or bulk conductivities of polymer gate electret layers played a critical role in determining the non-volatile memory properties.

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