Initial growth of AlN on clean and oxidized iron studied by AES and EELS

Abstract

AbstractWe have studied by Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) the room temperature growth of aluminium nitride (AlN) at the surface of clean and oxidized polycrystalline iron. The films were deposited by reactive rf‐sputtering in an N2‐Ar atmosphere. Very low coverages were possible thanks to a precise partial pressure controller based on electron impact emission spectroscopy (EIES).The AlN/Fe interface study has revealed the formation of an iron nitride at the surface of the substrate and of a compound close to AlN as a first monolayer. AlN clusters grow directly on this nitride layer and we did not detect the formation of any alloy between iron and aluminium. A modelization of the AES signal intensities suggests a Stranski‐Krastanov growth mode.For the oxidized iron, Auger lines showed an Fe2O3 surface layer on an Fe3O4 film oxide. The former oxide was reduced to Fe3O4 by the incoming aluminium which forms a two‐phase film made of Al2O3 and AlN resulting in an (AlN)x(Al2O3)1‐x stoichiometry. The concentration of this oxide phase decreases after the diffusion of the oxygen stops. Pure AlN begins to grow on this two‐phase film.