AN IN-SITU STUDY OF THE OXIDATION OF ALN LAYERS FABRICATED BY LPCVD USING X-RAY-DIFFRACTION

AlN layers were elaborated on SiC substrates using the method of low-p ressure chemical vapour deposition (LPCVD). The oxidation of these lay ers was studied in an X-ray diffraction chamber at temperatures betwee n 900 and 1400-degrees-C with an oxygen flow (20 SCCM) at a pressure o f 85 x 10(3) Pa. The oxidation was followed as a function of time at s everal temperatures by observing the intensity of the diffraction peak s of the phases formed. A t 1000-degrees-C, the action of oxygen leads to the formation of an oxynitride phase AlO(x)N(y) indicated by the a ppearance of the (400) peak. Between 1000 and 1400-degrees-C, the oxid ized phase is alpha-Al2O3, shown by the (012), (024) and (116) peaks. The kinetic elements thus obtained are discussed in terms of the morph ology of the oxidized surfaces.