Epitaxial growth of manganese silicide nanowires on Si(111)-7x7 surfaces

Reactive epitaxial growth of manganese silicide on a Si(111)-7x7 surface at low coverage is studied using scanning tunneling microscopy. Besides tabular and three-dimensional islands observed previously on the Mn/Si system, Mn silicide is found to form nanowires (NWs) on the Si(111)-7x7 surface at temperatures above similar to 500 degrees C. The NWs oriented along [101], [011], and [110], three equivalent directions, with equal probability. Well-ordered atomic arrangement observed on an ultrafine NW indicates that the NWs are crystalline. Scanning tunneling spectroscopy measurements show that the NWs exhibit a semiconducting character with a band gap of similar to 0.8 eV, which is consistent with that of bulk MnSi1.7. (c) 2007 American Institute of Physics.