Figure 1
From: Single-molecule sensing electrode embedded in-plane nanopore
Fabrication of electrode-embedded in-plane nanopore structure.
a, Schematic description of a microstructure used to form molecular-sized electrode-embedded nanopore consisting of a SiO2/Au/SiO2 multi-layer junction and micro-pillars on a SiO2/Si wafer. A gap is formed at the narrowed constriction of the Au layer by electromigration/self-breaking technique. In this way, the electrode gap and the nanoscale pore are automatically self-aligned to each other. b, Conductance versus time (G-t) trace during electrical breakdown of the multi-layer junction. The Au layer was first thinned gradually by current-induced electromigration (see Supplementary Fig. S2). The resulting atom-sized contact was then fractured spontaneously under a low constant voltage of 0.1 V. This self-breaking technique allowed formation of a sub-nanometer scale electrode gap. c–d, False-color scanning electron microscopy images of electrode gaps formed by the electromigration/self-breaking technique for SiO2/Au/SiO2 (c) and Au junction (d). The observations were conducted at the electron beam acceleration voltage of 15.0 kV and 5.0 kV for (c) and (d), respectively. Red square points to the location where electrode-embedded nanopore structure has been formed (see Supplementary Fig. S3 and S4). e–f, Electrode gap formation mechanism for the multi-layer junction (e) and the Au contact (f). Atom migration occurs in three dimension when there is no overlayer, leading to growth of a hillock (d,f). In contrast, SiO2 top layer forbids atomic flux in the cross-plane direction, forcing atoms to extrude at the side surface of the Au layer (c,e).
