Hexaaqua Metal Complexes for Low-Temperature Formation of Fully Metal Oxide Thin-Film Transistors

• Published in: Chemistry of materials 2015-08, Vol.27 (16), p.5808-5812
• Main Authors: Rim, You Seung, Chen, Huajun, Song, Tze-Bin, Bae, Sang-Hoon, Yang, Yang
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.5b02505

We investigated aqueous metal complex-based oxide semiconductor films formed with various ligands, such as chloride, acetate, fluoride, and nitrate. Nitrate ligand-based indium­(III) precursor was easily decomposed at low temperature due to the replacement of all nitrate ions with water during solvation to form the hexaaqua indium­(III) cation ([In­(H2O)6]3+). Hexaaqua indium­(III) cation was a key complex to realize high-quality oxide films at low temperature. Additionally, Al2O3-based high-k dielectric was also employed by using a nitrate precursor, and the hexaaqua aluminum­(III) cation ([Al­(H2O)6]3+) was confirmed. This complex-based Al2O3 film showed high breakdown voltage and stable capacitance under high frequency operation compared to organic solvent-based Al2O3 films. We successfully demonstrated aqueous-based In2O3 TFTs with Al2O3 high-k gate dielectrics formed at 250 °C with a wide gate voltage operation and high saturation mobility and on/off ratio of 36.31 ± 2.29 cm2 V–1 s–1 and over 107, respectively.