Amorphous In鈥揋a鈥揨n Oxide Semiconducting Thin Films with High Mobility from Electrochemically Generated Aqueous Nanocluster Inks

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• 作者：Athavan Nadarajah ; Mahkah Z. B. Wu ; Kevin Archila ; Matthew G. Kast ; Adam M. Smith ; Tsung H. Chiang ; Douglas A. Keszler ; John F. Wager ; Shannon W. Boettcher
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：August 25, 2015
• 年：2015
• 卷：27
• 期：16
• 页码：5587-5596
• 全文大小：572K
• ISSN：1520-5002

文摘

Solution processing is a scalable means of depositing large-area electronics for applications in displays, sensors, smart windows, and photovoltaics. However, solution routes typically yield films with electronic quality inferior to traditional vacuum deposition, as the solution precursors contain excess organic ligands, counterions, and/or solvent that leads to porosity in the final film. We show that electrolysis of aq. mixed metal nitrate salt solutions drives the formation of indium gallium zinc oxide (IGZO) precursor solutions, without purification, that consist of 鈭? nm radii metal鈥揾ydroxo clusters, minimal nitrate counterions, and no organic ligands. Films deposited from cluster precursors over a wide range of composition are smooth (roughness of 0.24 nm), homogeneous, dense (80% of crystalline phase), and crack-free. The transistor performance of IGZO films deposited from electrochemically synthesized clusters is compared to those from the starting nitrate salt solution, sol鈥揼el precursors, and, as a control, vacuum-sputter-deposited films. The average channel mobility (渭_AVE) of air-annealed cluster films (In:Ga:Zn = 69:12:19) at 400 掳C was 鈭? cm² V^鈥? s^鈥?, whereas those of control nitrate salt and sol鈥揼el precursor films were 鈭? and 鈭? cm² V^鈥? s^鈥?, respectively. By incorporating an ultrathin indium鈥搕in鈥搝inc oxide interface layer prior to IGZO film deposition and air-annealing at 550 掳C, a 渭_AVE of 鈭?0 cm² V^鈥? s^鈥? was achieved, exceeding that of sputtered IGZO control films. These data show that electrochemically derived cluster precursors yield films that are structurally and electrically superior to those deposited from metal nitrate salt and related organic sol鈥揼el precursor solutions and approach the quality of sputtered films.