Nanostructure fabrication by electron-beam-induced deposition with metal carbonyl precursor and water vapor

Nanorod fabrication is performed by electron beam induced deposition (EBID) with iron carbonyl [Fe(CO)₅] and tungsten carbonyl [W(CO) ₆] precursors. The effects of water vapor addition to each metal carbonyl on the microstructure and composition of the obtained nanorods are studied. Normally, EBID-fabricated metal nanorods consist of an amorphous phase containing a considerable amount of carbon. However, it is found that water vapor addition to iron carbonyl can effectively reduce the carbon content of the nanorods and induce the formation of carbon-free crystalline Fe ₃O₄ nanorods with increasing partial pressure ratio of water vapor to iron carbonyl. In contrast, for tungsten carbonyl, water vapor addition has no obvious effect on carbon content reduction. The obtained nanorods consist of a carbon-rich amorphous matrix containing tungsten oxide nanocrystals inside.