Preparation and characterization of AlN powders in the AlCl3–NH3–N2 system

Abstract

Fine aluminum nitride (AlN) powders were obtained by the chemical vapor deposition (CVD) process in the AlCl3–NH3–N2 system at the gas flow rate of 200cm3/min for both NH3 and N2. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED) were utilized to study the preparation and characterization of the AlN powders. While the reaction temperature of AlCl3 and NH3 is above 600°C, the AlN crystalloids are formed, however, the amorphous AlN powders are obtained below 600°C. When these powders are heat treated in NH3 atmosphere at temperatures above 1200°C, the amorphous AlN is converted to a crystallized state. The morphology of the particles and agglomerates of AlN is strongly dependent on the reaction temperature. The particle size of the AlN powders decreases from 210 to 12nm, as the reaction temperature increases from 600°C to 1150°C. The relation between the AlN particle size, Dnm, and the reaction temperature, T°C, is experimentally approximated as D=4830 exp(−5.225×10−3T).