Mechanistic investigation of the growth of Fe_(1-x)Co_xSi (0 ≤ x ≤ 1) and Fe5(Si_(1-y)Ge_y)3 (0 ≤ y ≤ 0.33) ternary alloy nanowires

摘要

We present the chemical vapor deposition (CVD) reactions of the single source precursor Fe(SiCl_3)_2(CO)_4 over Si, Ge, CoSi_2/Si, and CoSi/Si substrates to explore the growth and doping processes of silicide nanowires (NWs). Careful investigation of the composition and morphology of the NW products and the intruded silicide films from which they nucleate revealed that the group IV elements (Si, Ge) in the NW products originate from both the precursor and the substrate, while the metal elements incorporated into the NWs (Fe, Co) originate from vapor phase precursor delivery. The use of a Ge growth substrate enabled the successful synthesis of Fe_5Si_2Ge NWs, the first report of a metal silicide-germanide alloy NW. Further, investigation of the pyrolysis of the CoSiCl_3(CO)_4 precursor revealed independent delivery of Co and Si species during CVD reactions. This understanding enabled a new, more robust two-precursor synthetic route to Fe_(1-x)Co_xSi alloy NWs using Fe(SiCl_3)_2(CO)_4 and CoCl_2.