A Micro-pulse Process of Atomic Layer Deposition of Iron Oxide Using Ferrocene and Ozone Precursors and Ti-Doping

Hematite (-Fe2O3) thin films are obtained by atomic layer deposition (ALD) in the temperature range 200-350 degrees C using ferrocene and ozone as the precursors. A micro-pulse process facilitates the precursor adsorption and shortens the ferrocene dose time to 5 s. When tested on Si(100) substrates, the growth rate is around 0.5 angstrom per cycle for the first 300 cycles, after which the growth becomes nonlinear. Interestingly, a linear growth can be maintained with a rate of approximate to 0.55 angstrom per cycle by TiO2 co-deposition (cycle ratio of TiO2/Fe2O3=1:20). Characterizations by X-ray photoemission spectroscopy (XPS), Raman spectroscopy (RS), and UV-vis absorption confirm the presence of the -Fe2O3 phase after post-deposition annealing. Uniform depositions on dense ZnO nanorod arrays and anodic aluminum oxide (AAO) templates are also demonstrated, inferring that the current process is capable of coating on high (>50) aspect ratio structures.