Iron(III) tert-butoxide [Fe(OtBu)3]2 was applied as a single source (both Fe and O) precursor for the deposition of nanocrystalline hematite (Fe2O3)
or magnetite (Fe3O4) films by low-pressure CVD. The precursor decomposition pathway was derived from TGA/DTA data. The crystallization temperature of iron oxide was determined. Layer morphology and Fe/O stoichiometry was strongly substrate temperature - dependent.
The morphology of the grown films was studied by SEM, the phases and layer composition were analysed by XRD and XPS. Selective phase interconversion (Fe2O3 ↔ Fe3O4) with no particle size variation was achieved
by film ex-situ annealing under reducing or oxidizing conditions, respectively. The rate of precursor delivery and substrate temperature were controlling the mean layer grain size. Magnetite film having mean grain size of 10 nm was obtained on Si substrates
at 450 °C, whereas at higher temperatures larger grains and grain clusters were formed. Fe3O4 film having small grain size demonstrated superparamagnetic behavior with high coercivity (4000 Oe) and small saturation magnetization (0.3 emu g−1).
Fe3O4 and Fe2O3 layers deposited on glass substrates were transparent to the visible light, as was determined from the absorption spectra . Nanocrystalline Fe3O4 and Fe2O3 films demonstrated sheet resistance 2.4 kΩ and 2 MΩ, respectively.
[i]
[i] S. Mathur, M. Veith, V. Sivakov, H. Shen, V. Huch, U. Hartmann, H.‐B. Gao, Chem. Vapor. Dep., 2002, vol.8, Iss.6, p. 277-283, « Phase‐Selective Deposition and Microstructure Control in Iron Oxide Films Obtained by Single‐Source CVD», https://doi.org/10.1002/1521-3862(20021203)8:6<277::AID-CVDE277>3.0.CO;2-8, https://onlinelibrary.wiley.com/doi/pdf/10.1002/1521-3862%2820021203%298%3A6%3C277%3A%3AAID-CVDE277%3E3.0.CO%3B2-8