Solution Synthesis and Characterization of Indium-Zinc Formate Precursors for Transparent Conducting Oxides

A series of In Zn formate mixtures were investigated as potential precursors to amorphous In Zn-oxide (IZO) for transparent conducting oxide (TCO) applications. These mixtures were prepared by neutralization from formic acid and characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction, and thermogravimetry-differential scanning calorimetry (TG-DSC) measurements. Thermal analysis revealed that a mixture of In and Zn formates reduced the overall decomposition temperature compared to the individual constituents and that OH-substitution enhanced the effect. In terms of precursor feasibility, it was demonstrated that the decomposition products of In Zn formate could be directed toward oxidation or reduction by controlling the decomposition atmosphere or with solution acid additives. For TCO applications, amorphous IZO films were prepared by ultrasonic spray deposition from In Zn formate solutions with annealing at 300-400 degrees C.