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Science 10 January 1992:
Vol. 255. no. 5041, pp. 184 - 186
DOI: 10.1126/science.255.5041.184
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Articles

Electrical Resistivity and Stoichiometry of Kkhgr C60 Films

G. P. KOCHANSKI 1, A. F. HEBARD 1, R. C. HADDON 1, and A. T. FIORY 1

1 AT&T Bell Laboratories, Murray Hill, NJ 07974

Electrical resistances of polycrystalline fullerene (C60) films were monitored while the films were being doped in ultrahigh vacuum with potassium from a molecular-beam effusion source. Temperature- and concentration-dependent resistivities of Kkhgr C60 films in equilibrium near room temperature were measured. The resistance changes smoothly from metallic at khgr ap 3 to activated as khgr rarr = 0 or khgr rarr 6. The minimum resistivity for K3C60 films is 2.2 microohm-centimeters, near the Mott limit. The resistivities are interpreted in terms of a granular microstructure where K3C60 regions form nonpercolating grains, except perhaps at khgr ap 3. Stoichiometries at the resistivity extrema were determined by ex situ Rutherford backscattering spectrometry to be khgr = 3 ± 0.05 at the resistance minimum and khgr = 6 ± 0.05 at the fully doped resistance maximum.

Submitted on September 19, 1991
Accepted on November 7, 1991


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Electrical Resistivity and Stoichiometry of CaxC60 and SrxC60 Films.
R. C. Haddon, G. P. Kochanski, A. F. Hebard, A. T. Fiory, and R. C. Morris (1992)
Science 258, 1636-1638
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