Ab initio-guided X-ray photoelectron spectroscopy quantification of Ti vacancies in Ti1-dOxN1-x thin films

Ab initio calculations were employed to investigate the effect of oxygen concentration dependent Ti vacancies formation on the core electron binding energy shifts in cubic titanium oxynitride (Ti1-delta OxN1-x). It was shown, that the presence of a Ti vacancy reduces the 1s core electron binding energy of the first N neighbors by ~& nbsp;0.6 eV and that this effect is additive with respect to the number of vacancies. Hence it is predicted that the Ti vacancy concentration can be revealed from the intensity of the shifted components in the N 1s core spectra region. This notion was critically appraised by fitting the N 1s region obtained via X-ray photoelectron spectroscopy (XPS) measurements of Ti1-delta OxN1-x thin films deposited by high power pulsed magnetron sputtering. A model to quantify the Ti vacancy concentration based on the intensity ratio between the N 1s signal components, corresponding to N atoms with locally different Ti vacancy concentration, was developed. Herein a random vacancy distribution was assumed and the influence of surface oxidation from atmospheric exposure after deposition was considered. The so estimated vacancy concentrations are consistent with a model calculating the vacancy concentration based on the O concentrations determined by elastic recoil detection analysis and text book oxidation states and hence electroneutrality. Thus, we have unequivocally established that the formation and population of Ti vacancies in cubic Ti1-delta OxN1-x thin films can be quantified by XPS measurements from N 1s core electron binding energy shifts. (C)& nbsp;2022 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc.& nbsp;

Automated summary

Ab initio calculations were employed to investigate the effect of oxygen concentration dependent Ti vacancies on the core electron binding energy shifts in cubic titanium oxynitride. The study confirmed that Ti vacancy concentration can be quantified by intensity of shifted components in N 1s core spectra region.