## 2 Materials and Methods
### XPS Characterization
Changing the constant pass energy of the analyzer with a step of 5 eV from 50 eV (for wide scans) to 20 eV (for narrow scans), it was possible to prove that the Ag 3d\({}_{5/2}\) line kept its position and changes of the FWHM were registered. The uncertainty in reading a peak position is very low (1.002 ) for high resolution spectra. Therefore, after calibration procedures, we can trust the peak features we are going to acquire for films under investigation. The repeatability of data sets was ensured by the acquisition of the survey scan both at the beginning and at the end of each frame, in the acquisition program. Care was taken to transport the as-deposited films into XPS Laboratory, just a few meters ahead, using a glass jar in order to keep the surface clean from atmosphere contaminations. The objective of the research was to define via qualitative and quantitative XPS: (a) the phases present in each film according to different deposition conditions (for example the power voltage); (b) calculating the stoichiometry of the phase/phases revealed in the films, starting from the undersurface region, and going on by means of in-situ sputtering (alternating cycles of XPS acquisitions with sputtering ones); (c) acquiring core levels in the high resolution mode of at least two of the main adventitious contaminants, oxygen (O 1s) and carbon (C 1s), and defining the degree of purity of the films; (d) considering and verifying the homogeneity of the samples running parallel acquisition sets on different sputtered areas of the same film; (e) quantify the satellite contribution for each film, along its thickness, when we are sure there is no possibility that the satellite doublet can interfere \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \begin{tabular}{c} **ZrN** \\ **Sample** \\ **ID** \\ \end{tabular} & \begin{tabular}{c} **Sputter** \\ **Energy (V)** \\ \end{tabular} & \begin{tabular}{c} **Floating** \\ **Enabled** \\ **(V)** \\ \end{tabular} & \begin{tabular}{c} **Filament** \\ **Current** \\ **(μA)** \\ \end{tabular} & \begin{tabular}{c} **Bent** \\ **Voltage (V)** \\ \end{tabular} & \begin{tabular}{c} **Emission** \\ **Current** \\ **(mA)** \\ \end{tabular} & \begin{tabular}{c} **Geometry** \\ **Angle of the** \\ **Gun** \\ **(to the Normal)** \\ \end{tabular} & \
\begin{tabular}{c} **Ion-Beam-** \\ **Rastered Area** \\ **(mm\({}^{2}\))** \\ \end{tabular} & \multirow{2}{*}{**Cycles**} \\ \cline{1-1} \cline{6-6} A & 2 kV & No & 2 & No & 15 & 70\({}^{\circ}\) & 3 \(\times\) 3 (1 area) & 12 \\ \hline \multirow{2}{*}{B} & 2 kV &
\begin{tabular}{c} Yes \\ (\(-100\)) \\ \end{tabular} & \multirow{2}{*}{2} & Yes (1.76) & 3 & 70\({}^{\circ}\) & 3 \(\times\) 3 (2 areas) & 24 \\ \hline \multirow{2}{*}{C} & 2 kV & No & 2 & Yes (70) & 4 & 70\({}^{\circ}\) & 3 \(\times\) 3 (1 area) & 6 \\ \hline \multirow{2}{*}{D} & 2 kV & No & 2 & Yes (70) & 4 & 70\({}^{\circ}\) & 3 \(\times\) 3 (2 areas) & 10 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Sputtering parameters of the Ar+ ion gun related to an average pressure of 1.8 \(\times\) 10\({}^{-6}\) mbar in the main chamber during gentle erosion (group 1). with any unwanted resonant oxide compound; (f) using a new-fit function with respect to the one normally used (SLG (30), built in CasaXPS function fit), it was possible to establish the role of satellite quantification to apply in stoichiometry calculation of the films, according to point (b) in the list of objectives here considered. A presentation of the main results obtained for each sample is reported in the following subparagraphs. It was necessary to match Zr 3d with N 1s for data quantification, and even though the start and end points for each elemental spectrum were kept fixed, sometimes it was necessary to move them a little in order to minimize the residual standard deviation values.