Atomically Resolved Single-Walled Carbon Nanotube Intramolecular Junctions
Min Ouyang,1
Jin-Lin Huang,1
Chin Li Cheung,1
Charles M. Lieber12*
Intramolecular junctions in single-walled carbon nanotubes are
potentially ideal structures for building robust, molecular-scale electronics but have only been studied theoretically at the atomic level. Scanning tunneling microscopy was used to determine the atomic
structure and electronic properties of such junctions in single-walled
nanotube samples. Metal-semiconductor junctions are found to exhibit an
electronically sharp interface without localized junction states,
whereas a more diffuse interface and low-energy states are found in
metal-metal junctions. Tight-binding calculations for models based on
observed atomic structures show good agreement with spectroscopy and
provide insight into the topological defects forming intramolecular
junctions. These studies have important implications for applications
of present materials and provide a means for assessing efforts designed
to tailor intramolecular junctions for nanoelectronics.
1 Department of Chemistry and Chemical Biology
and
2 Division of Engineering and Applied Sciences,
Harvard University, Cambridge, MA 02138, USA.
*
To whom correspondence should be addressed. E-mail:
cml{at}cmliris.harvard.edu
