Attention was focussed here on the atomistic structure and stability of the TiN(100)

surface in contact with an oxidizing atmosphere. The early oxidation stages of

TiN(100) were investigated by means of first-principles molecular dynamics.

Selective oxidation of Ti atoms and the formation of an ultra-thin Ti oxide layer

was observed, while Ti vacancies were left behind at the metal/oxide interface. Within the formalism of ab initio thermodynamics, the segregation energies of

vacancies and vacancy clusters at the metal/oxide interface were computed:

comparing the stability of the system obtained by first-principles molecular

dynamics simulations with ideally reconstructed models. It was found that the

localization of Ti vacancies in the thin oxide layer and at the TiN/oxide interface

was thermodynamically stable and could account for the early removal of N atoms

from the interface by segregation of N vacancies from the bulk reservoir. It was

suggested that superficial oxidation could occur along two distinct pathways: a

thermodynamically stable path along the potential-energy minimum surface and a

metastable kinetically driven path that resulted from the high heat release during

the dissociation of O2.

Vacancy Segregation in the Initial Oxidation Stages of the TiN(100) Surface.

J.Zimmermann, M.W.Finnis, L.C.Ciacchi: Journal of Chemical Physics, 2009,

130[13], 134714