57Fe Mössbauer study of epitaxial TiN thin film grown on MgO (1 0 0) by magnetron sputtering
Sprache des Titels:
Englisch
Original Kurzfassung:
The properties and performance of TiN thin films are closely related to the concentration and mobility of lattice
defects in the thin film structures of TiN. This makes a local atomic scale study of TiN thin films an ever-growing
demand. Emission 57Fe Mössbauer spectroscopy (eMS) is a powerful tool in this regard, which we apply here to
study an ultrathin TiN film epitaxially grown on MgO (1 0 0). With the help of theoretical calculations, our
results show that most implanted Fe ions adopt a 2+ valence state and locate at the Ti sublattice in the bulk-like
single crystalline grains, with the rest Fe residing at the grain boundaries as interstitials. A small percentage of
nitrogen point defects (vacancy VN and interstitial NI) are observed in the bulk-like crystalline grains. A temperature-
dependent, interstitial NI mediated site-exchange between NI and VN inside the crystal grain are deduced
via a N2 dimmer like diffusion of NI through the crystal grains in the temperature range of 540?620 K. This
is interesting in the perspective of exploring the catalytic property of TiN nanostructures. The titanium vacancy (VTi) is only detected at the grain boundaries. Annealing up to 813 K, both the VN and NI are annihilated in the crystalline grains and the VTi is fully recovered with healing of the grain boundaries. However, no evidence of ferromagnetism due to dilute implantation of 57Mn/57Fe and or structural defects in the film is obtained. This suggests that the so far reported dilute magnetism and defect-induced ferromagnetism in TiN nanostructures requires a further systematic investigation.
Forschungs-