title: Indium oxide thin-film transistors processed at low temperature via ultrasonic spray pyrolysis.
abstract: The use of ultrasonic spray pyrolysis is demonstrated for the growth of polycrystalline, highly uniform indium oxide films at temperatures in the range of 200-300 °C in air using an aqueous In(NO3)3 precursor solution. Electrical characterization of as-deposited films by field-effect measurements reveals a strong dependence of the electron mobility on deposition temperature. Transistors fabricated at ∼250 °C exhibit optimum performance with maximum electron mobility values in the range of 15-20 cm(2) V (-1) s(-1) and current on/off ratio in excess of 10(6). Structural and compositional analysis of as-grown films by means of X-ray diffraction, diffuse scattering, and X-ray photoelectron spectroscopy reveal that layers deposited at 250 °C are denser and contain a reduced amount of hydroxyl groups as compared to films grown at either lower or higher temperatures. Microstructural analysis of semiconducting films deposited at 250 °C by high resolution cross-sectional transmission electron microscopy reveals that as-grown layers are extremely thin (∼7 nm) and composed of laterally large (30-60 nm) highly crystalline In2O3 domains. These unique characteristics of the In2O3 films are believed to be responsible for the high electron mobilities obtained from transistors fabricated at 250 °C. Our work demonstrates the ability to grow high quality low-dimensional In2O3 films and devices via ultrasonic spray pyrolysis over large area substrates while at the same time it provides guidelines for further material and device improvements.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Faber
authors.forename: Yen-Hung
authors.initials: YH
authors.lastname: Lin
authors.forename: Stuart R
authors.initials: SR
authors.lastname: Thomas
authors.forename: Kui
authors.initials: K
authors.lastname: Zhao
authors.forename: Nikos
authors.initials: N
authors.lastname: Pliatsikas
authors.forename: Martyn A
authors.initials: MA
authors.lastname: McLachlan
authors.forename: Aram
authors.initials: A
authors.lastname: Amassian
authors.forename: Panos A
authors.initials: PA
authors.lastname: Patsalas
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Anthopoulos
keywords: metal oxide; plastic electronics; spray pyrolysis; thin-film transistors