  By first lithographically fabricating contact electrodes and then as last
step growing carbon nanotubes with chemical vapour deposition across the
ready-made chip, many potential contamination mechanisms for nanotube devices
can be avoided. Combining this with pre-defined trenches on the chip, such that
the nanotubes are freely suspended above the substrate, enables the formation
of highly regular electronic systems. We show that, in addition, such suspended
ultra-clean nanotubes provide excellent high-frequency and low-dissipation
mechanical resonators. The motion detection mechanism of our experiment is
discussed, and we measure the effect of Coulomb blockade and the back-action of
single electron tunneling on the mechanical motion. In addition data on the
mechanical higher modes is presented.
