Structural analysis of AlN and (Ti1−<i>X</i>Al<i>X</i>)N coatings made by plasma enhanced chemical vapor deposition

Abstract

(Ti1−XAlX)N coatings were deposited by plasma enhanced chemical vapor deposition (PECVD) method using a gas mixture of TiCl4, AlCl3, NH3, H2 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 würtzite-structure was observed for 0.8&amp;lt;X&amp;lt;1.0. The lattice parameter changed linearly with the function X (d=4.241−0.197 X Å) in the single phase region. Metastable AlN particles with an NaCl structure and a lattice parameter of 4.03 Å were found on AlN coatings produced by PECVD using AlCl3, NH3 and H2. It was assumed that the formation of (Ti1−XAlX)N solid solution in a wide concentration range occurred due to the metastable AlN. When (Ti1−XAlX)N coatings were heat-treated at 1000 °C, AlN with a stable würtzite 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.