title: Ab initio study of the nature and stability of the defects and multi-vacancies in TaN. Comparison with TiN.
abstract: First principles calculations have been carried out to study the native single-defects and multi-vacancies in TaN and TiN with a cubic rocksalt structure mainly used as diffusion barriers. Our results indicate that vacancies are the most stable single-defects in both compounds and that nitrogen interstitial defects in tetrahedral interstitial site are significantly more stable in TaN than in TiN. The interactions between vacancies are attractive in TaN in contrast to the case of TiN. The vacancies show a much larger tendency to cluster and to form bi- and tri- vacancies in TaN than in TiN. We suggest that the number of d electrons might explain this difference in the defect stability. These results will have impact on the use of these materials as diffusion barrier.
authors.affiliation: Université de Montpellier, Institut Charles Gerhardt, UMR 5253 CNRS-UM-ENSCM, CC 1504, Place E Bataillon, 34095 Montpellier Cedex 5, France.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Boulat
authors.forename: Nicole
authors.initials: N
authors.lastname: Fréty
authors.forename: Pierre
authors.initials: P
authors.lastname: Sans
authors.forename: Romain
authors.initials: R
authors.lastname: Viennois