title: Toward the Limits of Uniformity of Mixed Metallicity SWCNT TFT Arrays with Spark-Synthesized and Surface-Density-Controlled Nanotube Networks.
abstract: We report the fabrication of thin film transistors (TFTs) from networks of nonbundled single-walled carbon nanotubes with controlled surface densities. Individual nanotubes were synthesized by using a spark generator-based floating catalyst CVD process. High uniformity and the control of SWCNT surface density were realized by mixing of the SWCNT aerosol in a turbulent flow mixer and monitoring the online number concentration with a condensation particle counter at the reactor outlet in real time. The networks consist of predominantly nonbundled SWCNTs with diameters of 1.0-1.3 nm, mean length of 3.97 μm, and metallic to semiconducting tube ratio of 1:2. The ON/OFF ratio and charge carrier mobility of SWCNT TFTs were simultaneously optimized through fabrication of devices with SWCNT surface densities ranging from 0.36 to 1.8 μm(-2) and channel lengths and widths from 5 to 100 μm and from 100 to 500 μm, respectively. The density optimized TFTs exhibited excellent performance figures with charge carrier mobilities up to 100 cm(2) V(-1) s(-1) and ON/OFF current ratios exceeding 1 × 10(6), combined with high uniformity and more than 99% of devices working as theoretically expected.
authors.affiliation: Department of Applied Physics, Aalto University School of Science , Puumiehenkuja 2, 00076 Aalto, Espoo, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Kaskela
authors.affiliation: Department of Applied Physics, Aalto University School of Science , Puumiehenkuja 2, 00076 Aalto, Espoo, Finland.
authors.forename: Kimmo
authors.initials: K
authors.lastname: Mustonen
authors.affiliation: Department of Applied Physics, Aalto University School of Science , Puumiehenkuja 2, 00076 Aalto, Espoo, Finland.
authors.forename: Patrik
authors.initials: P
authors.lastname: Laiho
authors.affiliation: Center of Integrated Research for Future Electronics, Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ohno
authors.affiliation: Department of Applied Physics, Aalto University School of Science , Puumiehenkuja 2, 00076 Aalto, Espoo, Finland.
authors.forename: Esko I
authors.initials: EI
authors.lastname: Kauppinen
keywords: aerosol technology; bundling control; floating catalyst chemical vapor deposition; single-walled carbon nanotubes; thin film transistors