Condensed Matter & Surface Sciences

COLLOQUIUM

Esko I. Kauppinen

Helsinki University of Technology, Finland

“Carbon Nanobud^TM – A Novel Nanomaterial:

Synthesis, Structure, Field Emission and Transport Properties”

We present synthesis, structure and field emission properties of a novel hybrid carbon nanomaterial, NanoBuds^TM, combining fullerenes and single-walled carbon nanotubes (CNTs). NanoBuds consist of fullerenes attached to the outside surface of CNTs, i.e. nanotubes are functionalized with fullerenes (1). Individual nanobuds were observed both by HR-TEM and micro-Raman, both showing fullerenes at tube surfaces and diving chirality information for the tubes. Fullerenes are attached to CNTs via either oxygen (preferable for fullerenes larger than C₅₄) or carboxylic (for smaller fullerenes) bridges, which was confirmed by FT-IR measurements. Scanning tunneling microscopy (STM) and spectroscopy (STS) measurements of samples deposited on Au(111) substrate confirmed the covalent nature of fullerene bonding to the tube. In-situ deposited i.e. non-purified planar NanoBud mats showed stable cold electron field emission with a current density of 189 µA/cm² at 1.26 V/µm. The threshold voltage was about 0.6 V/µm, compared to over 2 V/µm for similarly produced planar nanotube mats. We discuss sheet conductivity of nanotube and –bud films, as well as their optical absorption characteristics. Also, we discuss dry, ambient temperature deposition methods of thin films for transparent electrode and TFT-FET device manufacturing.

1. A. G. Nasibulin, P. V. Pikhitsa, H. Jiang, D. P. Brown, A. V. Krasheninnikov, A. S. Anisimov, P. Queipo, A. Moisala, D. Gonzalez, G. Lientschnig, A. Hassanien, S. D. Shandakov, G. Lolli, D. E. Resasco, M. Choi, D. Tománek, and E. I. Kauppinen, (2007) A Novel Hybrid Nanomaterial, Nature Nanotechnology 2(3), 156-161

Wednesday -- May 14, 2008

12:10 p.m. – Bentley Hall, Room 135

(NOTE SPECIAL DAY, TIME AND LOCATION)