Periodic array of intramolecular junctions of silicon nanowires

The formation of periodic arrays of intramolecular junctions in silicon nanowires from a single growth process is reported. Scanning tunneling microscopic images show intramolecular junctions formed by fusing together two straight wire segments (∼3nm in diameter) 5 and 10 nm long, respectively, at an angle of ∼30° with respect to each other. The junction repeats itself in a regular pattern along a nanowire, forming a striking superlattice ∼3nm in diameter and at least several microns long. Scanning tunneling spectroscopic measurements reveal distinctly different current-voltage curves for the two different segments changing sharply across each junction. The segments are most probably formed by a periodic change of growth direction while the different electronic properties of the two segments forming the junction are attributed to the differences in surface structure and segment diameter. © 2002 American Institute of Physics.