GermaniumÕcarbon core–sheath nanostructures

Germanium/carbon core–sheath nanostructures and junctions are produced when Ge nanowires are subject to a thermal treatment in an organic vapor doped vacuum. The organic molecules pyrolyze on the surface of the Ge nanowires and form a continuous graphitic coating. The carbon-sheathed Ge nanowires undergo melting and evaporation at high temperature, which results in the formation of germanium/carbon junctions. These core–sheath nanostructures and junctions generally have diameters of 5–100 nm, sheath thickness of 1–5 nm, and lengths up to several micrometers. This process may prove to be an effective approach to prevent the nanowire surface oxidation and create nanowires with chemically inert surface. © 2000 American Institute of Physics. @S0003-6951~00!01127-X#