Growth of AlN on clean and oxidised polycrystalline iron: an Auger study

Abstract

The growth of aluminium nitride (AlN) thin films on clean and oxidised polycrystalline iron was studied by Auger electron spectroscopy. The films of AlN were deposited by reactive RF sputtering (argon + nitrogen atmosphere). On clean iron, a modelisation of the Auger peak-to-peak intensities evidences a Stranski-Krastanov growth mode (one layer followed by island formation) with an interfacial layer made of iron nitride covered by the AlN. Results on oxidised iron suggested the growth of a two-phase film with stoichiometry gradient of the (AlN) x ( Al 2 O 3) 1− x form, x increasing with the film thickness. Grains of AlN in the layer were shown to favour the diffusion of oxygen from the substrate to the film until thicknesses of about 80 monolayers are reached. The presence of grains of both phases supports the hypothesis of an island growth mode for this interface.