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Science 19 June 1992:
Vol. 256. no. 5064, pp. 1662 - 1664
DOI: 10.1126/science.256.5064.1662
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Articles

Scanning Tunneling Spectroscopic Evidence for Granular Metallic Conductivity in Conducting Polymeric Polyaniline

D. Jeon 1, J. Kim 1, M. C. Gallagher 1, and R. F. Willis 1

1 Department of Physics, Pennsylvania State University, University Park, PA 16802

Scanning tunneling microscopy (STM) and point-probe electrical conductivity measurements of electrochemically protonated films of the emeraldine-base form of the conducting polymer, polyaniline are reported. The conductivity varies spatially, dependent on the size (LM \m=~\ 200 to 300 angstroms) of granular metallic regions which relate directly to the inhomogeneous micromorphology of the electrodeposited films. The normalized conductivity at zero bias is observed to increase with doping, indicating an increase in states at the Fermi level. The STM electronic measurements also show regions of negative differential resistance. Negative differential resistance is observed for all samples, although more frequently on less oxidized samples.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Scanning Tunneling Microscopy of Electrodeposited Ceramic Superlattices.
J. A. Switzer, R. P. Raffaelle, R. J. Phillips, C.-J. Hung, and T. D. Golden (1992)
Science 258, 1918-1921
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Science. ISSN 0036-8075 (print), 1095-9203 (online)