Air-stable nanogranular Fe thin films formed by Chemical Vapor Deposition of triiron dodecacarbonyl as catalysts for carbon nanotube growth

Thin, air-stable, nanogranular iron-based films of 10 ± 1.2, 100 ± 14 and 400 ± 46 nm thicknesses were prepared by Chemical Vapor Deposition (CVD) of triiron dodecacarbonyl, Fe₃(CO)₁₂, onto silicon wafers at 150 C in an inert environment at a standard pressure of 100 kPa. These thin nanogranular structured films, composed of sintered elemental Fe nanoparticles of 4.1 ± 0.7 nm diameter, are protected from oxidation by a very thin layer of carbon. The thickness of the Fe based films was controlled by changing the coating parameters such as coating time, concentration of the iron precursor, or by repeating the coating process. The saturation magnetization of these thin Fe coatings was similar to that of bulk iron. The electric resistivity of these films was thickness dependent. The morphology of these coatings was altered by annealing the films under argon, at a standard pressure of 100 kPa, at different temperatures (e.g., 350, 550 and 750 C). In the present manuscript, by CVD using ethylene as a carbon precursor, these Fe based films were used as a platform for synthesizing carpets of crystalline and vertically aligned carbon nanotubes.