Growth dynamics of titanium silicide nanowires observed with low-energy electron microscopy

Abstract
We report in situlow-energy electron microscopy observations of spontaneous nanowire (NW) formation during deposition of Ti on Si(111) at T∼850 ° C . The NWs are oriented primarily along {110} directions, with typical dimensions 50 nm wide, 20 nm high, and several microns long. The NW shape persists even at temperatures high enough to shrink the wires, suggesting that these are equilibrium shapes. During growth, the NW advances at both ends at a constant rate, independent of NW length or collisions with steps, which pile up at the ends. We argue that the rate-limiting kinetic step during growth is the reaction of silicide at the island ends. NWs that intersect during growth do not fuse, and will separate upon annealing. Occasionally, they form a temporary junction that connects and disconnects in an oscillating cycle.