CHEMICAL VAPOUR DEPOSITION OF THE Al-O-N SYSTEM

Abstract
Using chemical vapour deposition, aluminium - oxygen-nitrogen coatings have been synthesized with aluminium trichloride, hydrogen, ammonia and nitrous oxide. The composition of the equilibrium phases is first determined by a thermodynamic calculation. The only AlON phase we investigate is ([MATH]) spinel aluminium oxynitride and it is considered as a stoichiometric phase with a composition of Al₇O₉N. The results indicate the existence fields of aluminium nitride and alumina and show the difficulty of obtaining the spinel aluminium oxynitride without other phases. Temperature, pressure and gas composition play an important part because they directly influence the reactivity of aluminium chloride. A hot-wall reactor is used for the experimental study. In this way, we obtain AlN, a mixture of AlN and [MATH] AlON, and [MATH] Al₂O₃. The annealed deposits show the stability of AlON obtained at 1270K.