Formation of manganese silicide nanowires on Si(111) surfaces by the reactive epitaxy method

Manganese silicide nanowires (NWs) with a large length/width ratio have been predominantly formed on Si(111)- 7 × 7 surfaces with the reactive epitaxy method by a delicate control of growth parameters. The supply of free Si atoms per unit time plays a crucial role in the formation of the NWs. High growth temperature and low Mn deposition rate are favorable for the growth of long NWs with a large length/width ratio and the formation of islands with other shapes can be greatly restrained under these conditions. The formation of NWs is driven by the minimization of the strain energy caused by the lattice mismatch between the silicide and substrate. Scanning tunneling spectroscopy measurements show that the NWs exhibit a semiconducting character with a band gap of ~0.8 eV, which is consistent with that of bulk MnSi_1.7.