# A SiCN Thin Film Thermistor Based on DVB Modified Polymer-Derived Ceramics
## 3 Results
### Film Composition  
The XPS was employed to analyze the chemical composition and bonding characteristics within the film. The XPS spectra of DVB10-SiCN film pyrolyzed at 1100 \({}^{\circ}\)C are shown in Figure 4. The spectrum of Si (2p) shows peaks at 102.35 eV and 104.19 eV due to the formation of Si-N, Si-O bonds. For the C (1 s) spectrum, peaks were observed at 284.8 eV, 286.06 eV, and 288.25 eV and are attributed to C-C/C-H, C-O/C-N, and C=O, respectively. The highest intensity of the C-C peak indicates the completion of the pyrolysis process and the formation of free carbon. Similarly, for N (1 s) spectrum, the peaks at 399.35 eV, and  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **Si (wt\%)** & **C (wt\%)** & **N (wt\%)** & **O (wt\%)** \\ \hline SiCN & 32.75 & 17.89 & 2.02 & 47.34 \\ D10-SiCN & 31.87 & 19.24 & 3.23 & 45.67 \\ D20-SiCN & 32.64 & 18.99 & 4.84 & 43.53 \\ D30-SiCN & 33.35 & 20.01 & 2.31 & 44.33 \\ D40-SiCN & 29.46 & 23.29 & 5.52 & 41.72 \\ D50-SiCN & 31.20 & 22.69 & 3.92 & 42.19 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Results of elemental analysis.  
Figure 3: (**a**) Optical image showing SiCN thin film sensor. (**b**) SEM image showing a single DIW-SiCN line (inset shows EDS analysis conducted in the line scan mode). (**c**) Surface morphology of the DVB20-SiCN film. (**d**) SEM image showing the cross section of the DVB20-SiCN film (inset shows EDS analysis conducted in the line scan mode).  
400.95 eV correspond to C-N and Si-N, respectively. As for the O 1 s spectrum, two peaks centered at 532.4 eV and 533.87 eV, respectively, are associated with the Si-O band and adsorbed -OH, which is related to the oxygen contamination during the preparation [1]. The above results indicate the formation of free carbon-rich SiCN ceramics.  
Raman spectroscopy was used to further analyze the carbon in the SiCN films. The Raman spectra of the investigated SiCN ceramic films are shown in Figure 5. The spectra of SiCN modified with different DVB concentrations exhibit similar shape, which contains a D peak at \(\sim\)1333 cm\({}^{-1}\), and G peak at \(\sim\)1610 cm\({}^{-1}\), indicating a strong disorder state of the amorphous carbon. The intensity, position, and width of the D and G bands may vary, depending on the structural organization of the sample under study [22]. The intensity ratio of the D and G modes, \(I_{\rm D}/I_{\rm G}\), enables the evaluation of the carbon nanoparticle size by using the Ferrari-Robertson equation [22; 23]:  
\[\frac{I_{D}}{I_{G}}=\mathrm{C}^{\prime}(\lambda)L_{a}^{2} \tag{1}\]  
\(\mathrm{C}^{\prime}(\lambda)\) is a coefficient depending on the excitation wavelength of the laser. The value of \(\mathrm{C}^{\prime}(\lambda)\) for the wavelength of 532 nm is assigned to 0.6195 nm\({}^{-2}\)[24]. The \(L_{a}\) values are listed in  
Figure 4: XPS spectra of the as-prepared DVB20-SiCN film. (**a**) Si 2P spectrum. (**b**) C 1s spectrum. (**c**) N 1s spectrum. (**d**) O 1s spectrum.  
Table 2. The lateral cluster size La in all samples is between 1 nm and 2 nm, indicating the nanostructural nature of the free carbon in SiCN. Previous studies have shown that carbon in PDC SiCN will undergo precipitation during the pyrolysis process, and then evolve into free carbon [24]. The value of \(I_{D}/I_{G}\) is used to measure the disorder degree of free carbon, and the higher the ratio is, the higher the defect carbon content would be [25]. When the DVB content is 20 wt%, the \(I_{D}/I_{G}\) value suddenly increases, implying that the content of disordered carbon in SiCN gradually increases. The increase in \(L_{a}\) may be due to the in-plane growth of nano-polycrystalline graphite [23].