## 3 Results and Discussion
### Film Surface Morphology, Topology, and Structure Study  
All synthesized films were continuous and uniform. As can be seen from the SEM images presented in Figure 2, the surface of LPCVD films consists of spherical particles 20-40 nm in size and does not change significantly with T\({}_{\rm dep}\) in the studied temperature range (Figure 2a). In contrast to them, significant changes in the surface morphology of PECVD films were noticed with the synthesis temperature increasing. The surfaces of films obtained at T\({}_{\rm dep}\) = 373-473 K are smooth, homogeneous, and without any features (Figure 2b). There are rounded particles on the film surface synthesized at T\({}_{\rm dep}\) = 523 K  
Figure 1: Dependence of the film growth rate on the deposition temperature in LPCVD and PECVD processes.  
(Figure 2c). With a further increase in temperature to 673 K, the formation of nanowalls, uniformly distributed over the area of the sample, is observed. [57] (Figure 2d-f). The SEM image of the cross-section of such a structure is shown in Figure 2f. In this work, we limited ourselves to studying the physicochemical and functional properties of smooth films only; films consisting of nanowalls will be the object of study in another work.  
Figure 3a-c shows the AFM images of the surface of the LPCVD films. The root-mean-square (RMS) roughness of films deposited at 673, 873, and 973 K is 0.21, 1.33, and 1.54, respectively. The PECVD film obtained at T\({}_{\text{dep}}\) = 523 K has RMS equal to 1.64 nm (Figure 3d). The data indicates the formation of smooth films.  
Figure 3: 3D AFM images of the surface of the LPCVD films deposited at **(a)** 673, **(b)** 873, **(c)** 973 K, and **(d)** of the PECVD film obtained at T\({}_{\text{dep}}\) = 523 K. Scanning area is 10 \(\times\) 10 \(\upmu\)m\({}^{2}\).  
Figure 2: The typical SEM images for **(a)** LPCVD film and **(b)** PECVD films (T\({}_{\text{dep}}\) = 373–473 K). SEM images of PECVD films deposited at different temperatures: **(c)** 523 K, **(d)** 573 K, **(e)** 673 K. **(f)** Cross-section image of BC\({}_{\text{x}}\)N\({}_{\text{y}}\)/Si(100) structure, T\({}_{\text{dep}}\) = 673 K.  
Previously, we studied the temperature dependence of the RMS roughness of PECVD BC\({}_{\rm x}\)N\({}_{\rm y}\) films deposited using a mixture of trimethylborazine and nitrogen. The roughness varied from 0.5 to 2.6 nm with an increase in T\({}_{\rm dep}\) from 373 to 973 K [58]. Other authors [55] observed the same trend for LPCVD BC\({}_{\rm x}\)N\({}_{\rm y}\) films. An increase in the RMS roughness from 0.3 nm to 0.5 nm with an increase in temperature from 633 K to 773 K was found for films deposited using a mixture of dimethylamine borane and ammonia.  
Figure S2 shows the X-ray diffraction patterns of Si(100) substrate, the 190 nm thick film deposited at T\({}_{\rm dep}\) = 973 K and the 270 nm thick film deposited at T\({}_{\rm dep}\) = 523 K by LPCVD and PECVD, respectively. XRD patterns of films are similar to those of the substrate. They contain no reflexes, which indicates the amorphous nature of these films. The only peak at 20 = 33\({}^{\circ}\) corresponds to the Si(200) forbidden reflection of a substrate [59]. In other studies [40,41], BC\({}_{\rm x}\)N\({}_{\rm y}\) films deposited from TMAB were also found to be amorphous.