Figure 2: Correlated electrical and structural behaviour of a sulphide-filled CNT interconnect.
The electrically induced core removal process is tightly linked to the resistive hotspot dynamics and takes place in three well-defined stages: hotspot generation, migration and expansion. (a) Current passing through the nanotube and corresponding electrical resistance during the removal process shown in (c–k). The steep increase at ~40 s occurs when an Ohmic contact is established. The dotted vertical lines mark the corresponding position of panels (e) and (i). Elimination of the applied bias led to the abrupt fall in current at ~20 min. (b) Current–voltage relations taken at the initial and final stages of the removal process. A change from an almost insulating to an Ohmic system is visible and concurs with the event seen at ~40 s in (a). (c) Initial configuration of an isolated Zn0.92Ga0.08S@CNT connected to two Au electrodes. The insets in (c–j) are magnified views of the boxed regions. Plus and minus signs refer to temperatures above and below the sublimation point of the core sulphide, respectively. (d) The first stage of the removal process occurs selectively at one of the CNT ends and refers to the hotspot generation. Localized depletion of the core is evident from (c) to (d). (e–g) During the second stage, and past the Iguest=48 μA, the hotspot migrates to a position that is about one-third of the length between the two contact points. This process occurs in a matter of seconds and involves reversible solid–vapour phase transitions happening inside the CNT. (h–k) In the third stage, two core segments are progressively consumed by the expansion of the hotspot. Each segment front acts as a marker for the sulphide sublimation temperature (928 K). All scale bars, 0.5 μm.
