Vacancy-type defects in non-stoichiometric TiNx films, where x was between 0.901 and 1.04, which had been grown by using a reactive ion-plating method were studied by using mono-energetic positron beams. Doppler broadening profiles of the annihilation radiation, and the lifetime spectra of positrons, were measured as a function of the incident positron energy. The positrons annihilated from the trapped state mainly by vacancy-type defects. In the sub-surface region (below 200nm), 2 annihilation modes were observed which were associated with the annihilation of positrons in vacancy clusters and in voids located at grain boundaries. The nature of the vacancy clusters was found to be affected by the non-stoichiometry. The focussing collision mechanism in superlattice structures was important in the case of ion-implanted films.

A.Uedono, S.Nanao, S.Tanigawa, R.Suzuki, T.Ohdaira, T.Mikado, S.Ishibashi: Japanese Journal of Applied Physics, 1995, 34[I-10], 5711-6