Film growth mechanism of mist-chemical-vapor-deposited magnetite

Abstract

Crystal growth techniques using mist precursors, such as mist chemical vapor deposition (mist CVD), are useful for growing epitaxial thin films of various functional oxides under non-vacuum conditions and at relatively low temperatures. Their growth mechanism remains elusive, however, so we developed a home-made reaction chamber for mist CVD and investigated the epitaxial growth mechanism of magnetite Fe3O4 using alcoholic mists of iron acetylacetonate precursors. We show here that grown epitaxial films’ structural and physical properties depend on mist flow rates (or N2 carrier gas flow rates). Increasing the mist flow and promoting mists’ reactions on substrate surfaces produce Fe3O4 epitaxial films having larger magnetizations and lower electrical resistivities and exhibiting the Verwey transition. We also show that films’ properties are modified by changing either water additive concentrations in alcoholic mist solutions or the distance (the joint pipe length) between the mist bottle and the reaction chamber. Our results highlight the significance of the mist-flow-induced reactions for mist CVD epitaxial growth, providing new insight into the mechanism of epitaxial growth by mist CVD.