Microstructure and secular instability of the (Ti1 − x,Alx)N films prepared by ion-beam-assisted-deposition

(Ti1 − x,Alx)N films were prepared by ion beam assisted deposition (IBAD). The films were synthesized by depositing titanium and aluminum metal individual vapor under simultaneous bombardment with nitrogen ions in the energy range of 0.2–20 keV with the (Ti1 − x,Alx)/N transport ratio in the range of 0.5–2.0. The films were formed onto Si(111) wafers at room temperature. Structural characterization of the films was performed with x-ray diffraction and selected area electron diffraction. The crystalline structure of the (Ti0.64,Al0.36)N and (Ti0.33,Al0.67)N films were found to be a metastable single-phase B1-NaCl structure. The (Ti0.29,Al0.71)N films revealed a two-phase mixture consisting of NaCl and wurtzite structural phases. The AlN solubility limit into TiN, which approximately equal with x value, calculated by using electron theory was about x = 0.65, which shows good agreement to the experimental results. Phase separation after half a year of aging at room temperature in air was observed on the (Ti0.33,Al0.67) films whose AlN content is close to the solubility limits.