Structural analysis of AlN and (Ti1-xAlx)N coatings made by plasma enhanced chemical vapor deposition

(Ti1-XAlX)N coatings were deposited by plasma enhanced chemical vapor deposition (PECVD) method using a gas mixture of TiCl4, AlCl3, NH3, H-2 and Ar. X-ray diffraction and transmission electron microscopy were used to investigate the structure of the deposited (Ti1-XAlX)N coatings. They showed single phase NaCl-structure up to X=0.8, while a mixed phase of NaCl type (Ti0.2Al0.8)N and AlN with wurtzite-structure was observed for 0.8<X<1.0. The lattice parameter changed linearly with the function X (d=4.241-0.197 X Angstrom) in the single phase region. Metastable AlN particles with an NaCl structure and a lattice parameter of 4.03 Angstrom were found on AIN coatings produced by PECVD using AlCl3, NH3 and H-2. It was assumed that the formation of (Ti1-XAlX)N solid solution ina wide concentration range occurred due to the metastable AIN. When (Ti1-XAlX)N coatings were heat-treated at 1000 degrees C, AlN with a stable wurtzite structure precipitated. However, the broadened x-ray diffraction peak and the diffuse transmission electron microscopy diffraction patterns indicated that the amount of precipitation was not the same for each (Ti1-XAlX)N grain. (C) 1996 American Institute of Physics.