Special Condensed Matter Physics Seminar
Thursday, March 9, 2000, 12:30 p.m.
Plant Sciences Building, Room 1117
Carbon Nanotube Wires and Junctions
Zhen Yao
(Delft University of Technology, The Netherlands)
Abstract: Single-wall carbon nanotubes are single graphene
sheets rolled up into nanometer-diameter cylinders that can be either one-dimensional
metals or semiconductors, depending on how the sheets are rolled up.
An intramolecular junction seamlessly connecting two tube segments with
different atomic and electronic structures can be created by introducing
a pentagon and a heptagon into the hexagonal carbon lattice. I will
discuss electrical transport measurements of these fascinating wires and
junctions connected to nanofabricated metal electrodes. Individual
metallic nanotubes appear to be able to carry remarkably high current densities
exceeding a gigaampere per square cm without breaking down. I will
discuss the underlying phonon-scattering mechanism leading to the current
saturation observed at high electric fields. A metal-semiconductor
intramolecular junction behaves as the world's smallest rectifying diode.
In the case of a metal-metal junction, the conductance seems to be strongly
suppressed and it displays a power-law dependence on temperature and voltage,
consistent with tunneling between the ends of two one-dimensional correlated
electronic states, so-called Luttinger liquids. I will also discuss
electronic devices created by mechanical deformation.
Host: Ellen Williams
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