Critical current density for layer-by-layer breakdown of a multiwall carbon nanotube

Electric-current-induced structural changes in a suspended multiwall carbon nanotube (MWCNT) were observed through in situ transmission electron microscopy. The bias voltage and electric current were measured simultaneously as the MWCNT was imaged. The passage of excessive current led to breakdown of the surface of the MWCNT and to subsequent layer-by-layer removal of the broken outermost shell via sublimation of carbon atoms. The surface breakdown of the MWCNT was accompanied by a discrete decrease in the current. Under the assumption that the current passes solely through the outermost shell of the MWCNT, we found that the critical current densities at which the breakdown in the renewed outermost shell occurred after the removal of the broken outermost shell were limited to a remarkably narrow range of (2.4 ± 0.2) × 109 A/cm2, irrespective of the outermost diameter of the MWCNT. The present results provide invaluable information about electron transport phenomena in MWCNTs and about the durability of CNT nanocircuits. [Display omitted] •Electric-current-induced breakdown of the surface of an MWCNT is studied by in situ TEM.•Excessive current causes the successive layer-by-layer removal of outermost shells of the MWCNT.•The surface breakdown of the MWCNT occurs at a definite current density despite the number of shells.•The definite current density enables us to predict the critical current of the surface breakdown.