Microstructure and secular instability of the (Ti1-x,Al-x)N films preparedby ion-beam-assisted-deposition

(Ti1-x,Al-x)N films were prepared by ion beam assisted deposition (IBAD). T he films were synthesized by depositing titanium and aluminum metal individ ual vapor under simultaneous bombardment with nitrogen ions in the energy r ange of 0.2-20 keV with the (Ti1-x,Al-x)/N transport ratio in the range of 0.5-2.0. The films were formed onto Si(111) wafers at room temperature. Str uctural characterization of the films was performed with x-ray diffraction and selected area electron diffraction. The crystalline structure of the (T i-0.64,Al-0.36)N and (Ti-0.33,Al-0.67)N films were found to be a metastable single-phase B1-NaCl structure. The (Ti-0.29,Al-0.71)N films revealed a tw o-phase mixture consisting of NaCl and wurtzite structural phases. The AlN solubility limit into TiN, which approximately equal with x value, calculat ed 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 (Ti-0.33,Al-0.67) films whose AlN content is close to the solubility limits. (C) 2000 Kluwer Academic Pub lishers.