## 3 Results and Discussion
### Films' Composition and Chemical Bonding State
#### 3.3.2 FTIR Spectroscopy Data
The shift of maximum, large width, and the shape of the main band are typical for amorphous or highly disordered (possibly due to nitrogen and oxygen) BC\({}_{x}\) materials. It should be noted that the intensity of the main peak increases significantly with increasing the synthesis temperature. FTIR spectra of films deposited in the temperature region of 673-923 K have also a band of about 2530 cm\({}^{-1}\) which corresponds to B-H bonds. This band is not in the spectrum of film obtained at 973 K. The presence of the absorption bands ascribed to the hydrogenated groups such as C-H, N-H or O-H is not clearly confirmed in the spectra. Figure 6b shows Raman spectra of LPCVD films deposited at different temperatures. The spectra of the samples contain signals from the Si(100) substrate (520 cm\({}^{-1}\), 950 cm\({}^{-1}\)) [73]. The Raman spectrum of the film with a composition of B\({}_{0.80}\)C\({}_{0.14}\)N\({}_{0.04}\)O\({}_{0.02}\) deposited at 673 K exhibits a feature at 1140 cm\({}^{-1}\) which is characteristic of boron carbide [74]. The broadening of this band indicates the high amorphous and disordered character of the BC\({}_{x}\) film. Considering the film synthesized at 973 K, its Raman spectrum is typical of amorphous carbon and exhibits significant red-shift of the G and D peaks. Shift and broadening of these peaks indicate the amorphization and a decrease in the size of carbon particles [75]. Figure 7a presents the evolution of the FTIR absorption spectra of PECVD BC\({}_{x}\)N\({}_{y}\)O\({}_{z}\) films deposited in the temperature range of 373-673 K. The spectra of low-temperature films (373-523 K) differ from those of film obtained at 673 K, which is consistent with the difference in their elemental composition. The spectra of low-temperature films have the dominant band in the region of 1250 to 1770 cm\({}^{-1}\). The intensity of the band increases and its maximum shifts from 1405 to 1386 cm\({}^{-1}\) with increasing T\({}_{\rm dep}\). This band can be associated with in-plane vibrations of the B-N bonds in hexagonal BN. It should be noted that these peaks are wide, so the films should include complex chemical components and states. In this region, there are the bands corresponding to C-N, C=N and/or C=C stretching vibration modes. With an increase in the deposition temperature, a band also appears at about 800 cm\({}^{-1}\) due to out-of-plane vibrations of the B-N-B bonds in h-BN. Thus, it can be assumed that the chemical structure of the PECVD films is close to that of h-BN. The spectra also contain a broad low-intensity band with a maximum of 1100 cm\({}^{-1}\), which corresponds to vibrations of the B-C bond. Hydrogen-containing bonds are represented by N-H (3010-3700 cm\({}^{-1}\)) and C-H (2810-3000 cm\({}^{-1}\)) groups. The latter disappear with increasing film growth temperature. All the features besides the bands correspond to vibrations in h-BN and practically vanish for films obtained at higher deposition temperatures, as demonstrated by the spectrum of the PECVD film  
Figure 7: Evolution of **(a)** FTIR spectra and **(b)** Raman spectra of BC\({}_{x}\)N\({}_{y}\)O\({}_{z}\):H films obtained by PECVD methods using TMAB + N\({}_{2}\) mixture. Taking into account the EDX data on the presence of oxygen in the PECVD films, it is necessary to consider the presence of the B-O bonds (1420-1470 cm\({}^{-1}\) and 1263 cm\({}^{-1}\)) and B-OH groups (3230 cm\({}^{-1}\)) [73; 76; 77]. Raman spectra (Figure 7b) for PECVD films contain no features in the region of the G and D bands. Increasing the deposition temperature and the nitrogen content in the films lead to the increase of the luminescence background in Raman spectra.