  High quality single wall carbon nanotube quantum dots have been made showing
both metallic and semiconducting behavior. Some of the devices are identified
as small band gap semiconducting nanotubes with relatively high broad
conductance oscillations for hole transport through the valence band and low
conductance Coulomb blockade oscillations for electron transport through the
conduction band. The transition between these regimes illustrates that
transport evolves from being wave-like transmission known as Fabry-Perot
interference to single particle-like tunneling of electrons or holes. In the
intermediate regime four Coulomb blockade peaks appear in each Fabry-Perot
resonance, which is interpreted as entering the SU(4) Kondo regime. A bias
shift of opposite polarity for the Kondo resonances for one electron and one
hole in a shell is in some cases observed.
