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

Abstract

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 x 10(-3) cm(2)/Vs with negligible hysteresis under forward and reverse bias conditions.