We develop rational chemical strategies to synthesize novel one-dimensional nanowire materials of transition metal silicides, investigate their physical properties, and use them as nanoscale building blocks for the bottom-up assembly of integrated photonic, electronic, and spintronic nanosystems. Transition metal silicides are extremely important to microelectronics because of the ohmic contact and interconnect many silicides (NiSi, CoSi<sub>2</sub>, and TiSi<sub>2</sub>) provide. Furthermore, many silicides are direct bandgap semiconductors (CrSi<sub>2</sub>, β-FeSi<sub>2</sub>) and are promising for silicon-based photonics. The recent discovery of Fe<sub>x</sub>Co<sub>1-x</sub>Si alloys as ferromagnetic semiconductors make them promising for spintronic applications as well. Herein, we describe the chemical synthesis of free standing single-crystal nanowires (NWs) of FeSi, the only transition metal Kondo insulator and isostructural CoSi, an important metallic silicide for CMOS electronics. Straight and smooth FeSi and CoSi nanowires are produced on silicon substrates covered with a thin layer of silicon oxide through the decomposition of the single source organometallic precursors <i>trans</i>-Fe(SiCl<sub>3</sub>)<sub>2</sub>(CO)<sub>4</sub> and Co(SiCl<sub>3</sub>)(CO)<sub>4</sub>, respectively, in a simple chemical vapor deposition (CVD) process. Unlike typical vapor-liquid-solid (VLS) NW growth, silicide NWs form without the addition of metal catalysts, have no catalyst tips, and depend strongly on the surface employed. The physical properties of these new FeSi and CoSi nanowires, including electrical transport and X-ray spectroscopy, are reported. This general approach to silicide nanowire growth is likely to yield other functional silicide nanosystems with significant applications in nanoelectronics and nanophotonics, and for Fe<sub>x</sub>Co<sub>1-x</sub>Si, silicon based spintronics.
Conference Committee Involvement (1)
Nanomaterials Synthesis, Interfacing, and Integrating in Devices, Circuits, and Systems II