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

Abstract

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 degrees C using MLD with repeated sequential adsorptions of C=C 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 (similar to 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 cm(2)/V s, operating at - 1 V with an on/off current ratio of similar to 10(3).