Figure 3

Topographic and thermal images during electromigration.

(a)–(d) and (i)–(l) show the topography of nanowire devices at various stages of electromigration performed at room temperature (~300 K) and a low temperature (~100 K), respectively. (e)–(h) and (m)–(p) are the thermal images obtained under a small sinusoidal bias at ambient temperatures of ~300 K and ~100 K, respectively. The maximum temperatures of (e)–(h) and (m)–(p) are 311.4 K, 328.2 K, 385.8 K, 346.8 K, 108.2 K, 111.9 K, 122.2 K and 115.9 K, respectively. The temperature fields of Au nanowires were observed to change from symmetrical ((e)–(g) and (m)–(o)) to asymmetrical ((h) and (p)), about the dotted center line, as electromigration proceeded. The direction of electron flow (from cathode to anode) is indicated by the black arrow. The scale bar corresponds to 500 nm.