Direct photo-patternable organic-inorganic hybrid gate dielectric for organic thin-film transistors: Influence of the ZrO₂ content

An inorganic-organic hybrid gate dielectric was synthesized in a sol-gel reaction. 3-methacry loxypropyltrimethoxysilane serves as both an organosiloxane network former and an organic functional group whose photo-polymerization can permit negative-type photo-patternability. Addition of zirconium alkoxide leads to the uniform incorporation of ZrO₂ distributed in the matrix phase. At 170 °C, the obtained hybrid dielectric exhibits a smooth surface structure with an RMS roughness of ∼0.25 nm. The dielectric strength of the film was determined to be 1.2 ∼ 2.3 MV/cm. Increasing the amount of zirconium alkoxide effectively enhances the dielectric constant of the hybrid films from 5.3 to 6.6. The use of the gate dielectric with a high dielectric constant proves to be beneficial for fabricating an organic thin-film transistor. The organic thin-film transistor fabricated using the hybrid dielectric with a high dielectric constant shows a very low threshold voltage close to ̈0.4 V without deteriorating carrier mobility.