Composition, morphology and particle size control in nanocrystalline iron oxide films grown by single-source CVD

Nanocrystalline iron oxide films have been deposited onto various substrate s in a cold-wall CVD reactor using iron (III) tert-butoxide as a single-sou rce for iron and oxygen. Influence of the CVD parameters on the growth rate , chemical composition, morphology and crystalline phases has been investig ated. The Fe:O stoichiometry in the films is sensitive to the deposition co nditions, For instance, the interplay between precursor flux/deposition tem perature allows a fine control over deposition of different iron oxide phas es (hematite, maghemite and magnetite) and their interconversion. The diffe rent iron oxides could be detected by their typical morphological features and confirmed by XRD and XPS data of the deposits. At 350 degreesC and belo w, ultrafine amorphous iron oxide grains with size lower than 10 mn are pro duced which, can be transformed to crystalline hematite or magnetite phases by ex-situ annealing. Spinel-type Fe3O4 was formed as a singular phase on copper at 450 degreesC, which could be converted to Fe2O3 upon annealing. O n silicon, a mixture of magnetite and hematite was formed at 450 degreesC w hile a solid solution of the two phases resulted at 500 degreesC. Transmiss ion spectra of films deposited on glass show them to be transparent to visi ble light. The results are discussed in the light of XRD, SEM-EDX, XPS, AFM and elemental analysis.