Zirconium oxide dielectric layer grown by a surface sol–gel method for low-voltage, hysteresis-free, and high-mobility polymer field effect transistors

• We fabricated zirconium oxide layer by the surface sol–gel method.
• The fabricated ZrOx layer revealed good dielectric strength without additional treatment.
• The PFET fabricated on ZrOx layer showed nearly hysteresis-free and high mobility characteristics.

A simple, facile surface sol–gel method is introduced for the fabrication of zirconium oxide films for use as a dielectric layer of a solution-processed polymer field effect transistor (PFET). High dielectric strength is demonstrated for a zirconium oxide layer under room-temperature fabrication conditions using a surface sol–gel method without any post-treatments, which are typically needed in general sol–gel methods. X-ray photoemission spectroscopy showed that the fabricated zirconium oxide layer consists of inorganic ZrO2 and organic alkoxide groups, which can explain its marginal dielectric constant (∼9) and continuous film properties. In addition, by finishing the surface sol–gel synthesis at the stage of chemisorption, the hydrophobic nature of the final surface was retained, leading to a trap-free semiconductor/dielectric interface. As a result, the PFET made with a conventional polymeric semiconductor rendered nearly hysteresis-free and high mobility (0.3 cm2/V) characteristics at low voltage (<2 V).

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