Current saturation and electrical breakdown in multiwalled carbon nanotubes

We investigate the limits of high energy transport in multiwalled carbon na notubes (MWNTs). In contrast to metal wires, MWNTs do not fail in the conti nuous, accelerating manner typical of electromigration, Instead, they fail via a series of sharp, equally sized current steps. We assign these steps t o the sequential destruction of individual nanotube shells, consistent with the MWNT's concentric-shell geometry. Furthermore. the initiation of this failure is very sensitive to air exposure. In air failure is initiated by o xidation at a particular power, whereas in vacuum MWNTs can withstand much higher power densities and reach their full current carrying capacities.