## 3 Results and Discussion  
### Electrical Properties of the nc-SiO\({}_{x}\) Layer  
In order to optimize and enhance the efficiency of a solar cell, the electrical, as well as optical properties of the n-type nc-SiO\({}_{x}\) layer, can be varied. It can be applied to enhance carrier selectivity and rear side optical transmission, both of which are essentially significant in device operation. Our current research includes nc-SiO\({}_{x}\) material and its application in TOPCon solar cells as an optimized layer; where the goal is to provide the absorber layer with more light and ameliorate the selectivity of the carrier collection. A highly doped layer, as well as wide bandgap material, can assist with sharp band-bending, which enhances the carrier selectivity. Molybdenum-oxide, for instance, may be used as hole selective contacts. One of the key benefits of the nc-SiO\({}_{x}\) material is that the optical band-gap, or transparency, can be simply changed by various deposition conditions. The electrical conductivity was measuring the electrical (dark) conductivity (\(\sigma\)) in a planar electrode configuration (planar-conductivity), where current flows along the plane of the film, which we obtained around 1.1 \(\times\) 10\({}^{-1}\) S/cm. Parallel with the electrical (dark) conductivity (\(\sigma\)), the activation energy (Ea) was measured and estimated to be around 0.04 eV. The refractive index (n) of the nc-SiO\({}_{x}\) films was estimated from spectroscopic ellipsometric measurements. The measured refractive index (n) \(\sim\)2.9 at 600 nm indicates the excellent transparency of nc-SiO\({}_{x}\). The characteristic of the nc-SiO\({}_{x}\) layer deposited on the ultrathin SiO\({}_{2}\) passivation layer was shown by a cross-section transmission electron microscopy (TEM) image, as depicted in Figure 2. The thickness of the ultrathin SiO\({}_{2}\) passivation layer was recorded as 1.2 nm. After thermal annealing at 950 \({}^{\circ}\)C, crystallization of the Si-rich region was further promoted, as shown in Figure 2 with their max grain sizes.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Layers** & **Default Parameter** \\ \cline{2-3} SiN\({}_{x}\) dielectric & t = 70 nm \\ \cline{2-3} Front contact boundary & Standard texture surface (54.74\({}^{\circ}\)), \(w/o\) absorption loss, flat band \\ \cline{2-3} Front contact & MS Schottky contact model, SRV = 10 cm/s (assuming good passivation) \\ \cline{2-3} P+type Si layer & t = 0.3 \(\mu\)m, Na = 2 \(\times\) 10\({}^{2\circ}\) cm\({}^{-3}\), lifetime setting: 1 \(\mu\)s \\ \cline{2-3} n-type c-Si layer & t = 150 \(\mu\)m, Nd = 5.0 \(\times\) 10\({}^{16}\) cm\({}^{-3}\), lifetime setting: 1 \(\times\) 10\({}^{5}\)\(\mu\)s \\ \cline{2-3} Interface: SiOx & Chi = 1.0 eV, Eg = 8.9 eV, dk = 3.9, me = 0.98, mh = 0.49, Dph = 0 \\ \cline{2-3} nc-SiO\({}_{x}\) Si layer & t = 30 \(\mu\)m, Nd = 1 \(\times\) 10\({}^{17}\) cm\({}^{-3}\), lifetime setting: 50 \(\mu\)s \\ \cline{2-3} Rear contact & [PERSON] contact model, SRV = 10 cm/s \\ \cline{2-3} Rear contact boundary & A plane surface, \(w/o\) absorption loss, flat band \\ \cline{2-3} Ag electrode & t = 1 \(\mu\)m \\ \hline \hline \end{tabular}
\end{table}
Table 1: Simulation Parameters for TOPCon Solar Cell.  
Figure 2: Cross-section TEM images of nc-SiO\({}_{x}\) and ultrathin (\(\sim\)1.2 nm) SiO\({}_{2}\) layer.