Growth of Fe2O3 thin films by atomic layer deposition

Thin films of α-Fe2O3 (α-Al2O3-type crystal structure) and γ-Fe2O3 (defect-spinel-type crystal structure) have been grown by the atomic layer deposition (ALD) technique with Fe(thd)3 (iron derivative of Hthd = 2,2,6,6-tetramethylheptane-3,5-dione) and ozone as precursors. It has been shown that an ALD window exists between 160 and 210 °C. The films have been characterized by various techniques and are shown to comprise (001)-oriented columns of α-Fe2O3 with no in-plane orientation when grown on soda-lime-glass and Si(100) substrates. Good quality films have been made with thicknesses ranging from 10 to 130 nm. Films grown on α-Al2O3(001) and MgO(100) substrates have the α-Fe2O3 and γ-Fe2O3 crystal structure, respectively, and consist of highly oriented columns with in-plane orientations matching those of the substrates.