Electrical transport in pure and boron-doped carbon nanotubes

The resistivities of individual multiwalled pure and boron-doped carbon nan otubes have been measured in the temperature range from 25 to 300 degrees C . The connection patterns were formed by depositing two-terminal tungsten w ires on a nanotube using focused-ion-beam lithography. A decrease of the re sistivity with increasing temperature, i.e., a semiconductor-like behavior, was found for both B-doped and pure carbon nanotubes. B-doped nanotubes ha ve a reduced room-temperature resistivity (7.4 X 10(-7) - 7.7 X 10(-6) Ohm m) as compared to pure nanotubes (5.3 X 10(-6) - 1.9 X 10(-5) Ohm m), makin g the resistivity of the doped tubes comparable to those along the basal pl ane of graphite. The activation energy derived from the resistivity versus temperature Arrhenius plots was found to be smaller for the B-doped (55-70 meV) than for the pure multiwalled nanotubes (190-290 meV). (C) 1999 Americ an Institute of Physics. [S0003-6951(99)03021-1].