Supplementary material for the paper

Shortening of the CNT and the diminishing of the fullerene caused by carbon evaporation

Figure s3 shows the evolution of a fullerene hinge with time. When the connection is subjected to electrical solicitation, the geometry changes, the fullerene diameter decreases, and the CNT shortens due to carbon evaporation.

Figures s3(a)–s3(p). TEM images showing other examples of using the fullerene as an “electrical hinge.” The left CNT is similar to that in Figure 2. The fullerene was located on a cluster of graphite flakes (G) on the right-hand side. Typically in (i), the left CNT, the fullerene, and the right graphene flakes are shaded separately, for guiding the eyes. The fullerene changed its position, shape, and diameter during the I–V sweeping process. The diameter decrease (from an initial 2.7 ± 0.1 nm to 1.9 ± 0.1 nm) was due to the high-temperature-induced evaporation of carbon atoms during the mode I, II, and III connections, respectively. Arrows in figures indicate the position of the fullerene. All figures have the same magnification. Bar = 10 nm.
Aside from the change in contact geometry, other features observed in the fullerene hinge are the shortening of the CNT and the decrease in the fullerene diameter. Figure s3 shows these effects. The CNT was shortened by ~10 nm from Figures s3 (a)–(p), and simultaneously, the fullerene was shrunk by about 30%. There are two possibilities for these features. The first possibility is the knocking off of the carbon atoms due to e-beam irradiation, which is frequently observed during TEM observation [29]. However, TEM is a relatively slow process and the diameter and length of the CNT should simultaneously decrease. Considering that only a slight diameter decrease was observed, e-beam irradiation considered as a minor effect. Instead, the evaporation of the carbon atoms at the contact site was regarded as the main reason. Carbon evaporation is a result of the high temperature created during the I–V measurements. According to previous reports, a temperature of nearly 3000 K can be achieved using the current experimental setup, where carbon evaporation could be observed [30, 31].

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