Nanotube structure and electronic properties probed by scanning tunneling microscopy

Scanning tunneling microscopy (STM) has been used to investigate the structure and electronic properties of carbon nanotubes produced from a discharge between graphite electrodes. STM images of the nanotubes deposited onto polycrystalline gold substrates resolve the three-dimensional structure of the nanotubes and show that these tubes often exist as tightly packed bundles. In addition, bias-voltage dependent imaging studies indicate that the nanotubes studied are semiconductors. The implications of these new data to the application of nanotubes in structural composites and nanoelectronics is discussed.