High-Quality Solution-Processed Metal-Oxide Gate Dielectrics Realized with a Photo-Activated Metal-Oxide Nanocluster Precursor

High-quality solution-derived amorphous alumina (a-Al₂O₃) dielectric has been achieved with [Al 13(μ3-OH 6μ-OH)₁₈ (H₂O)₂₄](NO₃)₁₅(Al-13 nanocluster) as a precursor and a local structure-controllable activation process via deep-UV-induced photochemical activation. The synergetic combination of an Al-13 nanocluster precursor and high-energetic photochemical activation enables the formation of highly dense a-Al₂O₃ thin films via an efficient dissociation and rearrangement of the nanocluster skeleton. The electrical characteristics of the nanocluster-based a-Al₂O₃ thin films were investigated in terms of their operative electronic conduction mechanism by comparing conventional nitrate-based and vacuum-deposited films. From these results, it was found that the leakage current density of solution-processed a-Al₂O₃ layers is largely affected by their precursor structures. Finally, to demonstrate the versatility of the high-quality nanocluster-based a-Al₂O₃ dielectrics, carbon nanotube and metal-oxide thin-film transistors were fabricated on low thermal budget stretchable and rigid substrates, respectively.