Preparation of Iron Oxide Thin Films by MOCVD

Polymorphous Transformations of Nanometric Iron(III) Oxide: A Review

“…β-Fe 2 O 3 is an iron(III) oxide polymorph that has not been found in nature but has been synthesized as a powder, , colloidal nanostructure, hollow nanoparticles, , and/or thin films. , Interestingly, β-Fe 2 O 3 is the only iron(III) oxide polymorph that exhibits paramagnetism at room temperature. The preparation of pure β-Fe 2 O 3 is quite difficult; only a few synthetic methods for the preparation of pure, mostly nanosized β-Fe 2 O 3 have been reported to date.…”

“…It was found that the thermal stability of the β-Fe 2 O 3 film was significantly dependent on the presence of Si dopants. Iron(III) acetylacetonate has also been used as a precursor for the chemical vapor deposition of a single phase β-Fe 2 O 3 thin film at 600 °C under a flow of oxygen . More commonly, β-Fe 2 O 3 has been identified as a component of a mixture of Fe 2 O 3 polymorphs; ,, such mixtures may arise from the simultaneous formation of two Fe 2 O 3 polymorphs (e.g., β-Fe 2 O 3 and γ-Fe 2 O 3 ) and/or polymorphous transformations of β-Fe 2 O 3 and γ-Fe 2 O 3 to α-Fe 2 O 3 .…”

“…Iron(III) acetylacetonate has also been used as a precursor for the chemical vapor deposition of a single phase β-Fe 2 O 3 thin film at 600 °C under a flow of oxygen. 138 Several researchers have independently confirmed that the β-Fe 2 O 3 polymorph is unstable at temperatures between 400 and 600 °C, 52À55,58,139 with the precise decomposition temperature depending on the nature of the sample (powder, hollow nanostructure, or thin film). However, β-Fe 2 O 3 is much more thermally stable than ε-Fe 2 O 3 .…”

α-Fe2O3 versus β-Fe2O3: Controlling the Phase of the Transformation Product of ε-Fe2O3 in the Fe2O3/SiO2 System

“…Similar dependence of the phase composition on the oxygen fugacity may be found in the articles dealing with thin films of iron oxide prepared by CVD and CVC techniques using coordination complexes of iron with an organic ligand (iron acetylacetonate, − Fe(trifluoroacetylacetonato) 3 or Fe(hexafluoroacetylacetonato) 2 ·TMEDA (TMEDA = N , N , N ′, N ′-tetramethylethylenediamine) . Fujii et al studied the influence of the O 2 flow rate and the substrate temperature on the phase composition of the iron oxide thin films obtained by decomposition of Fe(acac) 3 .…”

“…Ueyama et al observed similar dependence of the composition of the thin layersthe increasing O 2 flow rate resulted in a gradual shift from a mixture of Fe 3 O 4+δ and β-Fe 2 O 3 to the pure beta iron oxide thin film. 16 Carraro et al used a TMEDA-modified iron acetylacetonate complex. 18 They obtained the beta phase at the substrate temperature of 500 °C and O 2 flow rate of 20 sccm and also ε-Fe 2 O 3 at 400 °C and flow rate of 100 sccm together with an additional 100 sccm passed through water and introduced directly to the reaction chamber.…”