Nanofibers comprised of copolymer polyaniline/polyethylene blends are being investigated for use in nanoelectronic applications such as field effect transistors and ultra-small antennas. The nanofibers were fabricated by an electrospinning technique, wherein a high voltage (typically 8 kV, with electrodes spaced 20 cm apart) is applied to a solution comprised of polyethylene oxide and polyaniline doped with camphorsulfonic acid in dissolved in CHCl3. Nanofibers are formed when the charge overcomes the surface tension of the polymer solution[1,2]. The nanofibers in this study are nominally 100 -200 nm in diameter and up to 150 microns long. By comparison, earlier conducting fibers fabricated using a similar process were 950 to 2100 nm in diameter. Prior to depositing the nanofibers, gold electrodes, spaced 2-10 microns apart, were evaporated onto the oxidized silicon substrate. Electrical resistance measurements indicated resistance values that range from 2×109 to 1×1010 ohms. These values indicate that the resistivity of the 100 nm nanowires is approximately 0.2 ohm-cm, which is lower than the 10 ohm-cm values reported for thicker (400 -600 nm) fibers. This is the first time that electrical measurements of 100 nm diameter polyaniline/polyethylene have been reported. More detailed studies of the conduction mechanism for these nanofibers, as well as the dependence of resistivity on fiber diameter and doping concentration, is currently under investigation. Experimental data from gated electrical resistance measurements, wherein the resistance of the nanofibers is modulated using a bias voltage applied across the insulating SiO2 layer, will be presented. References: 1. I.D. Norris, M.M. Shaker, F.K. Ko, and A.G. MacDiarmid, Electrostatic Fabrication of Ultrafine Conducting Fibers: Polyaniline/Polyethylene Oxide Blends, Synthetic Metals 114, p. 109-114 (2000). 2. A.G. MacDiarmid, W.E. Jones, I.D. Norris, J. Gao, A.T. Johnson, N.J. Pinto, H. Hone, B. Han, F.K. Ko, H. Okuzaki, and M. Llaguno, Electrostatically Generated Nanofibers of Electronic Polymers, Synthetic Metals 119, p. 27-30 (2001).
Journal: TechConnect Briefs
Volume: 3, Technical Proceedings of the 2003 Nanotechnology Conference and Trade Show, Volume 3
Published: February 23, 2003
Pages: 301 - 304
Industry sectors: Advanced Materials & Manufacturing | Sensors, MEMS, Electronics