Resonant electron scattering by defects in single-walled carbon nanotubes

We report the characterization of defects in individual metallic single-wal led carbon nanotubes by transport measurements and scanned gate microscopy. A sizable fraction of metallic nanotubes grown by chemical vapor depositio n exhibits strongly gate voltage-dependent resistance at room temperature. Scanned gate measurements reveal that this behavior originates from resonan t electron scattering by defects in the nanotube as the Fermi Level is vari ed by the gate voltage. The reflection coefficient at the peak of a scatter ing resonance was determined to be about 0.5 at room temperature. An intrat ube quantum dot device formed by two defects is demonstrated by Low-tempera ture transport measurements.