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Electronic Conductance Behavior Of Carbon-Based Molecular Junctions With Conjugated Structures
Published 2002 · Chemistry
A novel molecular junction based on a monolayer between carbon and mercury “contacts” was investigated by examining current/voltage behavior as a function of temperature and monolayer thickness. Monolayers of phenyl, biphenyl, and terphenyl were covalently bonded to flat, graphitic carbon, then a top contact was formed with a suspended mercury drop. Similar molecular junctions were formed from multilayer nitroazobenzene (NAB) films of 30 A and 47 A thickness, and junctions were examined over the temperature range of +80 °C to −50 °C. Junction resistances were a strong function of molecular length and structure, with mean resistances for 0.78 mm2 junctions of 34.4 Ω, 13.8 KΩ, and 41.0 KΩ for phenyl, biphenyl, and terphenyl junctions. The i/V characteristics of biphenyl and phenyl junctions were nearly independent of temperature, while those of terphenyl and NAB junctions were temperature independent below 0 °C but thermally activated above 10 °C. The results are consistent with a tunneling process at low t...