# Structure and Electrical Properties of Carbon-Rich Polymer Derived Silicon Carbonitride (SiCN)
## 3 Results and Discussion
### Investigation of the Carbon Phase
The inter-defect distance, L\({}_{\text{D}}\), and relatively defect density, \(\eta_{\text{D}}\) of the samples also show dependence on the annealing temperature with which the monoliths were produced. An increase in the inter-defect distance of the sp\({}^{2}\) hybridized carbon structure as annealing temperature increases invariably led to the corresponding reduction in the defect densities, \(\eta_{\text{D}}\) (see Figure 2c). The surge in L\({}_{\text{D}}\) could be attributed to the progressive sp\({}^{3}\) to sp\({}^{2}\) conversion and indeed ordering of the graphitic structure noticed between 1100 \({}^{\circ}\)C \(\leq\) T \(\leq\) 1600 \({}^{\circ}\)C. Meanwhile, the recorded inter-defect distance on the C/SiCN nanocomposites in this study is higher when compared with C/SiOC PDCs produced under similar temperature conditions [46, 53]. The L\({}_{\text{D}}\) values are also more favourable than other polymer-derived SiCN materials found in the literature -although the recently proposed Cancado equation was not adopted in the studies [44, 45, 54, 55]. This shows that the carbon-rich SiCN materials contain minimum defects and this could be associated with the fabrication parameters used in the production of the sample series. \[\text{L}_{\text{D}}=\sqrt{(1.8\times 10^{-9})\,\tilde{\Lambda}_{\text{L}}^{ \ast}\left(\frac{A_{\text{C}}}{A_{0}}\right)} \tag{2}\]  
\[\text{L}_{\text{eq}}\ =\ 33.6343\,\left(\frac{A_{2D}}{A_{D}}\right) \tag{3}\]  
\[\text{\text{\texteta}}  
SiCN is evaluated using XRD. The X-ray diffraction pattern confirms that the material is amorphous at 1100 \({}^{\circ}\)C as no reflections were shown at this temperature (Figure 3). However, reflections indicating the crystallization of the samples were revealed at T \(\geq\) 1400 \({}^{\circ}\)C and assigned to the \(\beta\)-SiC (F-43m, Pearson symbol: cf8) as the major crystalline phase with traces of sacking faults (SF) [59, 60, 61]. Further investigation of the normalized diffraction intensities reveals that as the temperature increases from 1400 \({}^{\circ}\)C to 1600 \({}^{\circ}\)C, the stacking fault (SF) in the \(\beta\)-SiC becomes healed or suppressed by over 50%. This observation could be linked to the rising stability of beta-SiC with the temperature increase. \(\beta\)-SiC have been widely investigated as semiconductors for applications in microelectromechanical systems (MEMS) [62, 63, 64]. Electrical conductivity in graphitic PDC materials has however been attributed to the percolation network of the free carbon (as long as the C to Si ratio is \(\geq\)0.7) [58]. The dominating character of free carbon on the electrical properties of the carbon rich SiCN materials could be traced to its high conductivity of 1-10\({}^{5}\) (S/cm) compared with the conductivity of SiC which is within the range of 10\({}^{-4}\) -10\({}^{2}\) (S/cm) [14]. This, however, depends on composition and processing conditions that could promote change in hybridization of the carbon atom for sufficient sp\({}^{3}\) to sp\({}^{2}\) transformation as pyrolysis temperature is increased [33]. SiC has been described as a compound semiconductor with a wide bandgap and several advantages over silicon [65]. Hole carrier mobility in SiC polytypes is very small and the majority of the carrier concentration are electrons for the fabrication of n-type semiconductors [66]. In a recent report, [PERSON] et al. divulged the need to account for the relationship between the conductivity of the free carbon and that of the Si-C-N in materials [13]. [PERSON] et al. equally reported the possibility of the notable contribution of (SiOC PDC precipitated) nano-crystalline SiC grains to the overall electrical properties [67]. In essence, the carrier transport mechanism in polycrystalline materials may