AN EELS INVESTIGATION OF OXYGEN LOCALIZATION IN THE ALN STRUCTURE

The aim of the present work is to investigate by electron energy loss spectroscopy the structural differences between oxygen-doped aluminium nitride deposits (AlON) which are characterized by strong changes in their surface morphology. The deposits have been obtained by chemical vapour deposition using AlCl3 and NH3 as precursors. Progressive addition of N2O in the gas mixture makes possible the introduction of oxygen atoms in the 2H-AlN lattice. Quantitative analysis suggests that well-crystallized materials showing a feather-like surface morphology correspond to the insertion of oxygen atoms in the empty sites of the AlN structure, while for less-crystallized materials, associated with spherolitic surface morphology and a higher oxygen content, the oxygen atoms are substituted for nitrogen atoms. These two kinds of localization for the oxygen atoms can be deduced from the radial distribution function, which was determined by analysing the extended energy loss fine structure, observed on the aluminium, nitrogen and oxygen K-edges.