Some properties of aluminium nitride powder synthesized by low-pressure chemical vapour deposition

Abstract

Aluminium nitride (AIN) powders were synthesized by a low-pressure chemical vapour deposition, i.e. reactions of vaporized aluminium with various compositions of NH₃-N₂ gases at 1050°C under a pressure of 0.1–1.3 kPa. The properties of the resulting powders were divided into three categories, according to the NH₃ content in the NH₃-N₂ gases: (i) 0 ⩽ NH₃ < 40%, (ii) 40⩽NH₃⩽60%, and (iii) 60<NH₃⩽100%. In Region (i), the unreacted aluminium adhered to the AIN crystallites to form spherical primary particles; in Region (ii), the spherical agglomerates with diameters of 0.2–0.5 μm, composed of primary particles, were present as minimum units of secondary particles; in Region (iii), the crystal growth of AIN was enhanced with increasing NH₃ contents. The primary particles formed by the reaction of aluminium vapour with NH₃-N₂ gases containing NH₃⩾40% were single crystals.