Synthesis of Ti-Cr-N thin films by reactive ion-beam mixing of Ti/Cr interfaces

Titanium/chromium interfaces produced by titanium thin film deposition on chromium substrates have been reactively mixed using N2+ ion-beams of 2 and 3 keV at room temperature (RT). The ion-beam mixing (IBM) has been analysed using X-ray photoelectron spectroscopy (XPS), angle-resolved X-ray photoelectron spectroscopy (ARXPS) and Monte Carlo TRIDYN simulations. Below ∼2 × 1016 ions/cm2, the IBM kinetic is characterised by a strong decrease of the Ti concentration along with a fast nitrogen incorporation, that can be explained mainly by Ti sputtering and nitrogen implantation. Above that ion dose, the Ti/Cr ratio can be varied in a broad range maintaining nearly constant the nitrogen concentration (∼50%), as a consequence of sputtering, nitruration and mixing effects taking place simultaneously. ARXPS results show that the composition of the ternary films formed by reactive IBM is rather uniform in the near surface region. The comparison of experimental results with those obtained from TRIDYN, that uses pure ballistic mechanisms, suggests that the chemical reaction with the nitrogen partial pressure and processes driven by residual defects are the rate-controlling mechanisms during the reactive IBM of Ti/Cr interfaces.