Inkjet-printed high quality gate oxide for fully printed IGZO transistors

To print thin-film transistors and avoid vacuum deposition and lithography processes, a high-quality printed insulator is required in addition to semiconductors and conductors. A straightforward method for printing a dense and thin gate oxide with a leakage current of less than 38 nA/cm
²
at 1 MV/cm, a breakdown voltage greater than 4.5 MV/cm, and a relative permittivity of approximately 10 is described in this paper. We printed these TFTs on finely polished high purity aluminum sheets. After preparing the Al substrate with controlled oxidation to create the gate dielectric, we prepared a fresh solution of NH
4
OH:H
2
O
2
:H
2
O and immediately inkjet printed it on the substrate. Hereby the gate oxide is formed after 10 min without any additional annealing process. We rinsed the devices in ultrapure water and blow-dried them with nitrogen for 10 minutes after printing. Afterward, we printed and annealed indium gallium zinc oxide (IGZO) as a semiconductor. Finally, we printed the sources/drains and contacts with silver ink.