Controllable threshold voltage of a pentacene field-effect transistor based on a double-dielectric structure

• A pentacene field-effect transistor based on a double-dielectric structure of CYTOP and SiO2 is fabricated.
• Application of a positive switching voltage to a gate electrode induces a large threshold voltage shift from −4.4 to 4.6 V.
• The threshold voltage shift is attributed to electron trapping at the CYTOP/SiO2 interface.
• The change of threshold voltage is reversible and very stable.
• A memory device is realized by utilizing the double-dielectric structure.

The authors report controllable threshold voltage (Vth) in a pentacene field-effect transistor based on a double-dielectric structure of poly(perfluoroalkenyl vinyl ether) (CYTOP) and SiO2. When a positive switching voltage is applied to the gate electrode of the transistor, electrons traverse through the pentacene and CYTOP layers and subsequently trapped at the CYTOP/SiO2 interface. The trapped electrons induce accumulation of additional holes in the pentacene conducting channel, resulting in a large Vth shift from −4.4 to +4.6 V. By applying a negative switching voltage, the trapped electrons are removed from the CYTOP/SiO2 interface, resulting in Vth returning to an initial value. The Vth shift caused by this floating gate-like effect is reversible and very time-stable allowing the transistor to be applicable to a nonvolatile memory that has excellent retention stability of stored data.

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