title: Far-UV Annealed Inkjet-Printed In2O3Semiconductor Layers for Thin-Film Transistors on a Flexible Polyethylene Naphthalate Substrate.
abstract: The inkjet-printing process of precursor solutions containing In nitrate dissolved in 2-methoxyethanol is optimized using ethylene glycol as a cosolvent that allows the stabilization of the droplet formation, leading to a robust, repeatable printing process. The inkjet-printed precursor films are then converted to In2O3semiconductors at flexible-substrate-compatible low temperatures (150-200 °C) using combined far-ultraviolet (FUV) exposure at ∼160 nm and thermal treatment. The compositional nature of the precursor-to-metal oxide conversion is studied using grazing incidence X-ray diffraction (GIXRD), X-ray reflectivity (XRR), and Fourier transform infrared (FTIR) spectroscopy that indicate that amorphous, high density (up to 5.87 g/cm3), and low impurity In2O3films can be obtained using the combined annealing technique. Prolonged annealing (180 min) at 150 °C yields enhancement-mode TFTs with saturation mobility of 4.3 cm2/(Vs) and ∼1 cm2/(Vs) on rigid Si/SiO2and flexible plastic PEN substrates, respectively. This paves the way for manufacturing relatively high-performance, printed metal-oxide TFT arrays on cheap, flexible substrate for commercial applications.
authors.affiliation: VTT Technical Research Centre of Finland, Ltd. , Tietotie 3, FI-02044 Espoo, Finland.
authors.forename: Jaakko
authors.identifier: http://orcid.org/0000-0001-5865-0135
authors.initials: J
authors.lastname: Leppäniemi
authors.affiliation: VTT Technical Research Centre of Finland, Ltd. , Tietotie 3, FI-02044 Espoo, Finland.
authors.forename: Kim
authors.initials: K
authors.lastname: Eiroma
authors.affiliation: VTT Technical Research Centre of Finland, Ltd. , Tietotie 3, FI-02044 Espoo, Finland.
authors.forename: Himadri
authors.initials: H
authors.lastname: Majumdar
authors.affiliation: VTT Technical Research Centre of Finland, Ltd. , Tietotie 3, FI-02044 Espoo, Finland.
authors.forename: Ari
authors.initials: A
authors.lastname: Alastalo
keywords: inkjet printing; low-temperature annealing; metal oxide; plastic substrate; printed transistor; thin-film transistor