Transition-metal nitrides were used in a variety of applications because of their renowned hardness and stability. Departure from the nominal 1:1 stoichiometry was often observed for transition-metal nitrides and, therefore, defects have a prevalent role on transition-metal nitride physical properties. Here, the results of first-principles calculations on N and metal point defects in the prototype system of TiN and in HfN and ZrN were reported. Features were found which were common to all systems, while key differences were also identified. In certain cases—for example, N interstitials in TiN—the interaction between defects was attractive and it favors the formation of defect complexes. Other defects, like N interstitials in HfN and ZrN, did not pair up. Results were presented concerning the effect of point defects upon the electronic properties of TiN. Pertinent experimental data and the implications of the findings to the thermal stability of transition-metal nitride films were considered.

Structure and Interaction of Point Defects in Transition-Metal Nitrides. L.Tsetseris, N.Kalfagiannis, S.Logothetidis, S.T.Pantelides: Physical Review B, 2007, 76[22], 224107 (7pp)