Subject Area C4: Semimetal-Semiconductor Nanowires
Stefan Mendach, Kornelius Nielsch
Bismuth is a semimetal with a highly anisotropic Fermi surface and a
very small effective mass of the electrons meff = 0.001 me. Therefore it
exhibits quantum effects already at rather large structure sizes of approximately 100 nm.
In this subject area nanowires consisting of bismuth and bismuth-antimony compounds are fabricated
in Al2O3 pore structures. The wire diameter or the chemical composition is varied
during fabrication. Depending on the diameter and the chemical composition the nanowires are either
semimetals or semiconductors.
The thermoelectric properties, for example, the Seebeck coefficient and the thermal conductivity,
will be determined by the three-omega method.
Left: Theoretical phase diagram.
Right: Semimetal-semiconductor nanowires can be made from bismuth by varying the diameter or
from bismuth-antimony compounds by varying the chemical composition along the wire axis.
W. Lee, R. Ji, U. Gösele and K. Nielsch,
"Fast fabrication of long-range ordered porous alumina membranes by hard anodization"
Nature Materials 5, 741-747 (2006).
J. Lee, S. Farhangfar, R.B. Yang, R. Scholz, M. Alexe, U. Gösele, J. Lee and K. Nielsch,
"A novel approach for fabrication of bismuth-silicon dioxide core-shell structures by atomic layer deposition",
Journal of Materials Chemistry 19, 7050-7054 (2009).
Y. M. Lin, O. Rabin, S. B. Rabin, J. Y. Ying, and M. S. Dresselhaus,
"Semimetal-semiconductor transition in Bi1-xSbx alloy nanowires their thermoelectric properties",
Appl. Phys. Lett. 81, 2403-2405 (2002).
Semiconductor-metal transitions in single Bi/Sb nanowires
Magnetic-field dependent determination of the thermoelectric figure of merit