Phase mixture in MOCVD and reactive sputtering TiOxNy thin films revealed and quantified by XPS factorial analysis

Titanium oxynitride thin films have been deposited by low-pressure metalorganic chemical vapour deposition and reactive sputtering. The growth temperature for chemical vapour-deposited films and water vapour partial pressure for sputter-deposited films have been used to modulate the chemical composition. Both series have been analysed using X-ray photoelectron spectroscopy (XPS) in order to describe the structure of the materials using a factorial analysis approach. Titanium and metalloid concentrations have also been determined and compared to an elemental analysis performed using Rutherford backscattering spectroscopy and nuclear reaction analysis. The two deposition methods led to the synthesis of TiOxNy coatings exhibiting various oxygen and nitrogen concentrations from metallic TiN to insulating TiO2 compounds. Taking into account the Ti 2p signals of XPS spectra and implementing the factorial analysis, both series exhibited the coexistence of two phases, namely Ti(N,O) and TiO2. Quantification of each phase has been calculated and discussed as a function of the deposition conditions.