## 3 Results and Discussion
### Films' Composition and Chemical Bonding State
#### 3.3.3 XPS Analysis
In addition, the C1s spectra show several weak peaks with a binding energy in the region of 286.9-289.0 eV, the presence of which is determined by the formation of oxygen-containing bonds (alcohol, carboxyl, carbonate groups) [83]. Table 4 shows the binding energies of the C1s peaks, as well as the proportion of different states of carbon (%). Figure 8: XPS spectra of (a) B 1s, (b) C 1s, and (c) N 1s core levels for LPCVD BC\({}_{x}\)N\({}_{y}\) films deposited at different temperatures. \begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Bonding Structures**} & \multirow{2}{*}{**Position, eV**} & \multicolumn{4}{c}{**Area, \%**} \\ \cline{3-5}  & & **Tdep = 673 K** & **Tdep = 873 K** & **Tdep = 973 K** \\ \hline B–B/B–C in B\({}_{4}\)C & 188.0 & 56 & 28 & 13 \\ B–C in BC\({}_{x}\) & 189.0 & 32 & 53 & 58 \\ B–C\({}_{n}\)N\({}_{3-n}\) & 189.9 & 8 & 12 & 21 \\ B–N in h-BN & 190.9 & 3 & 6 & 5 \\ B–(C/N)\({}_{n}\)O\({}_{3-n}\) & 191.9 & 1 & 1 & 3 \\ \hline \end{tabular}
\end{table} 
Table 3: Fine structure of B1s spectra of the LPCVD BC\({}_{x}\)N\({}_{y}\) films deposited at different temperatures. Figure 8c shows the N1s spectra of the studied films. According to the literature data, the values of the binding energies for nitrogen included in the h-BN and BC\({}_{x}\)N\({}_{y}\) structure lie at 398 eV [31; 80; 81; 84] and 398.7-399.3 eV [80; 85], respectively. In the case of nitrite and nitrate groups, even higher binding energies of the N1s peak are observed in the region of 401-403 eV [40; 86]. These ranges were chosen to create a model describing the structure of the N1s spectra. Table 5 shows the binding energies of the N1s peaks, as well as the proportion of one or another state of nitrogen (%). XPS study of the PECVD film deposited at 523 K was carried out, and its composition was determined as B\({}_{0.30}\)C\({}_{0.27}\)N\({}_{0.29}\)O\({}_{0.14}\). Figure 9 represents the 1s core level spectra of boron, carbon, nitrogen, and oxygen. The curves of the B1s, C1s, N1s, and O1s peaks were fitted. The B1s spectrum exhibits at least four components centered at 189.1, 190.0, 190.9, and 192.0 eV which corresponds to the contribution from B-C in BC\({}_{x}\), B-C\({}_{n}\)N\({}_{3-n}\), B-N in sp\({}^{2}\) BN, and B-(C/N)\({}_{n}\)O\({}_{3-n}\) bonds, respectively. The C 1s spectrum was deconvoluted into six peaks at 283.1 eV (C-B bonds), 284.5 eV (sp\({}^{2}\) carbon), 286.0 eV (C-N\({}_{n}\)B\({}_{3-n}\) bonds), 286.9 eV (C-O/C-(N/B)\({}_{n}\)O\({}_{3-n}\)), 287.8 eV and 288.7 eV (C=O bonds arising from surface functional groups). Deconvolution of the N1s signal resulted in three component peaks corresponding to sp\({}^{2}\) N-B (398.4 eV), N-B\({}_{n}\)C\({}_{3-n}\) (399.5 eV) and N-(B/C)\({}_{n}\)O\({}_{3-n}\) (400.5 eV), respectively. O1s spectrum was also deconvoluted into four peaks which are assigned to O=C (530.9 eV), O-B (531.6 eV), O-C (532.5), and O-H (533.4 eV) bonds, respectively [52; 87; 88]. In the results of the XPS measurements, the near-surface layer of the LPCVD films is composed mainly of boron and carbon, the contents of which change from 59 to 46 at.% and from 26 to 36 at.% in the temperature range of 673-973 K, respectively. The portion of nitrogen and oxygen does not exceed 6 at.% and 12 at.%, respectively. The dominant bond in these films is the B-C bond. It should be noted that the composition of PECVD films varies greatly. In this case, dominant bonds are B-N, hybrid B-N-C (BN\({}_{3}\)-like configuration) and oxygen-containing bonds. While B-C bond content is insignificant. The results of the XPS study correlate well with EDX, FTIR, and Raman spectroscopy data.