Abstract
Vacancy-type defects in nonstoichiometric TiNx films (0.901≤x≤1.04) grown by a reactive ion-plating method were probed by monoenergetic positron beams. Doppler broadening profiles of the annihilation radiation and lifetime spectra of positrons were measured as a function of incident positron energy. In the TiNx films, positrons mainly annihilated from the trapped state by vacancy-type defects. In the subsurface region ( <200 nm), two annihilation modes associated with the annihilation of positrons in vacancy clusters and in voids located at grain boundaries were observed. The species of vacancy clusters was found to be influenced by nonstoichiometric conditions. For ion-implanted TiN films, the importance of the focusing collision mechanism in superlattice structures was discussed.