  We use a simultaneous flow of ethylene and hydrogen gases to grow single wall
carbon nanotubes by chemical vapor deposition. Strong coupling to the gate is
inferred from transport measurements for both metallic and semiconducting
tubes. At low-temperatures, our samples act as single-electron transistors
where the transport mechanism is mainly governed by Coulomb blockade. The
measurements reveal very rich quantized energy level spectra spanning from
valence to conduction band. The Coulomb diamonds have similar addition energies
on both sides of the semiconducting gap. Signatures of subbands population has
been observed.
