Monolayer-precision fabrication of mixed-organic–inorganic nanohybrid superlattices for flexible electronic devices

We report a low-temperature fabrication of mixed-organic–inorganic nanohybrid superlattices for high-k thin stable gate dielectrics on flexible substrates. The self-assembled organic layers (SAOLs) were grown by repeated sequential adsorptions of C C-terminated alkylsilane and metal (Al or Ti) hydroxyl with ozone activation, which was called “molecular layer deposition (MLD)”. 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. The TiO2 and Al2O3 inorganic layers were grown by ALD, which relies on sequential saturated surface reactions resulting in the formation of a monolayer in each sequence and is a potentially powerful method for preparing high quality multicomponent superlattices. The MLD method combined with ALD (MLD–ALD) was applied to fabricate SAOLs-Al2O3–SAOLs-TiO2 nanohybrid superlattices on polycarbonate substrates with accurate control of film thickness, large-scale uniformity, excellent conformality, good reproducibility, multilayer processing capability, sharp interfaces, and excellent film qualities at relatively low temperature. The prepared ultrathin nanohybrid films exhibited good thermal and mechanical stability, good flexibility, excellent insulating properties, and relatively high dielectric constant k (6–11). The MLD–ALD method is an ideal fabrication technique for various flexible electronic devices.