Growth of n-type organic semiconductor for low-voltage transistors based on an ALD grown Al2O3 gate dielectric

•N-type low-voltage OFETs using F16CuPc and Al2O3 were fabricated and characterized.•Crystallographic analysis of F16CuPc film on an ALD grown Al2O3 dielectric was carried out.•Surface of an ALD grown Al2O3 dielectric affects molecular arrangement in F16CuPc thin-film.•Growth in in-plane grain size of F16CuPc leads to device performance enhancement.

N-type low-voltage organic field-effect transistors (OFETs) were fabricated using copper hexadecafluorophthalocyanine (F16CuPc) and aluminum oxide (Al2O3) as a semiconductor and gate dielectric, respectively. The Al2O3 gate dielectric (30 nm) was grown by atomic layer deposition (ALD) and F16CuPc thin-film was deposited through a thermal vacuum evaporation method over the bare or self-assembled monolayer treated Al2O3 gate dielectric. The electrical characteristics of the gate dielectric were investigated using a metal–insulator–metal capacitor type device. The molecular arrangements and crystallographic analysis of the F16CuPc thin-film formed on the gate dielectric were carried out in detail using an atomic force microscope (AFM) and grazing incidence X-ray diffraction (GIXD) experiments. The crystal growth mode varies depending on the surface properties of the nano-gate dielectric. The nano-gate dielectric affects the molecular arrangement and crystal size in the thin-film and lead to the difference in device performance. The average field-effect mobility of the device based on a self-assembled monolayer treated gate dielectric was 2.21 × 10−3 cm2/Vs with negligible hysteresis under forward and reverse bias conditions.

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