Atomic structure and electronic properties of single-wall carbon nanotubes probed by scanning tunneling microscope at room temperature

Abstract

A detailed three-dimensional structural analysis of single-walled carbon nanotubes was carried out using a scanning tunneling microscope (STM) operated at room temperature in ambient conditions. On a microscopic scale, the images show tubes condensed in ropes as well as tubes which are separated from each other. For a single-wall nanotube rope, the outer portion is composed of highly oriented nanotubes with nearly uniform diameter and chirality. On separated nanotubes, atomically resolved images show variable chirality ranges between 0°–30°, and variable diameter (1–3 nm), with no one type dominant. From STM and scanning tunneling spectroscopy measurements we confirmed the correlation between chirality and the electronic properties, namely the tuning from metallic to semiconducting. We also observed a rectifying behavior correlated with the chiral angle of 25°, an important observation for nanodevices application.

Atomic structure of carbon nanotubes from scanning tunneling microscopy

“…Topographic imaging can be combined with tunneling spectroscopy measurements. [5][6][7][8] This is a powerful technique since the predicted relation between atomic and electronic structure can be tested. STM measurements indeed confirmed that nanotubes can be either semiconducting or metallic, depending on the chirality and diameter.…”

FTIR studies of nitrogen doped carbon nanotubes

“…High quality and well-aligned carbon nanotubes are essential for the applications in the field of nanoelectronics and many of these applications are dependent upon the chirality and diameter of CNTs [7]. The nanotubes can be either metallic or semiconducting depending upon their diameter and chirality.…”

Presence of Perfectly Conducting Channel in Metallic Carbon Nanotubes

“…[2][3][4][5][6][7][8][9][10][11] These predictions have been confirmed by Raman experiments 12) and direct measurements of local density of states by scanning tunneling spectroscopy. [13][14][15] In this paper we shall investigate effects of potential scattering in metallic nanotubes in the case of the presence of several current carrying channels.…”