Two types of MWNT breakdown observed in this experiment. In the type-I breakdown, the curve shows little nonlinearity up to the breakdown point and exhibits stepwise drops of the conductance during the electrical breakdown (a). On the other hand, the type-II breakdown is characterized by the sharp transient increase in the curve, which appears in both curves obtained in a vacuum (b) and in air (c). The insets are the characteristics corresponding to each curve.
A result of the stepwise measurement conducted in a vacuum. Small conductance steps seen in the inset are indicative of modifications of MWNT∕Au contacts. After the transient increase of the conductance, the curve became nonlinear, perhaps due to partial ablation of the outermost shell of the nanotube.
The peak bias voltage is plotted against the maximum conductance for MWNTs that have undergone the type-II breakdown. The data points nicely lie on a horizontal straight line for the type II in vacuum, indicating that the conductance attains a peak at a constant bias . On the other hand, obtained in air shows some scatter.
Log-log correlation between the breakdown power and the low-bias resistance for MWNTs showing the type-I and the type-II breakdowns. The dashed line is a power-law fit to the plot obtained in vacuum with , which reveals a certain correlation between the for the type-II breakdown and the .
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