Molecular layer deposition of ZrO2-based organic–inorganic nanohybrid thin films for organic thin film transistors

Molecular layer deposition (MLD) technique can be used for preparation of various organic–inorganic nanohybrid superlattices at a gas-phase. The MLD method is a self-controlled layer-by-layer growth process under vacuum conditions, and is perfectly compatible with the atomic layer deposition (ALD) method. In this paper, we fabricated a new type organic–inorganic nanohybrid thin film using MLD method combined with ALD. A self-assembled organic layer (SAOL) was formed at 170 °C using MLD with repeated sequential adsorptions of CC terminated alkylsilane and zirconium hydroxyl with ozone activation. A ZrO2 inorganic nanolayer was deposited at the same temperature using ALD with alternating surface-saturating reactions of Zr(OC(CH3)3)4 and H2O. The prepared SAOL-ZrO2 organic–inorganic nanohybrid films exhibited good mechanical stability, excellent insulating properties, and relatively high dielectric constant k (~ 16). They were then used as a 23 nm-thick dielectric for low voltage pentacene-based thin film transistors, which showed a maximum field effect mobility of 0.63 cm2/V s, operating at − 1 V with an on/off current ratio of ~ 103.