## 3 Results and Discussion
This highlights what was previously mentioned, that k and, consequently, \(\alpha\), are dictated by the SE model-based analysis approach. Conversely, for the 700 \({}^{\circ}\)C SiC samples up to A2 annealing, \(\alpha\) decreases (CU model), reaching values below 10\({}^{2}\) cm\({}^{-1}\), comparable to the reference SiO\({}_{2}\) sample, followed by a substantial increase in the A3-annealed samples (\(\sim\)2000 cm\({}^{-1}\) for the CU model). For A1- and A2-annealed 700 \({}^{\circ}\)C SiC thin films, the analysis reveals absorption values below 200 cm\({}^{-1}\) at telecom wavelengths, regardless of the model employed, demonstrating the high optical quality achieved. Figure 5(Ci) shows representative PLE spectra for the reference SiO\({}_{2}\) sample and the 650 \({}^{\circ}\)C and 700 \({}^{\circ}\)C AD SiC films. The reference sample demonstrated zero PLE intensity, a critical finding that corroborates the absorption values obtained from SE analysis, regardless of the models (CL and CU) used. Also, consistent with the higher absorption coefficient extracted from SE, the 650 \({}^{\circ}\)C film exhibited a substantially higher PLE intensity (\(\sim\)10 times higher integrated PLE intensity) compared to the 700 \({}^{\circ}\)C film, which exhibited overall minimal PLE. The 700 \({}^{\circ}\)C film subjected to A2 annealing showed a further decrease in PLE intensity, again aligning with SE-derived absorption trends. This trend was spatially uniform across the samples' area, as shown in the corresponding intensity mappings of a 5 \(\times\) 5 \(\upmu\)m\({}^{2}\) area in Figure 5(Cii,Ciii) for the 650 \({}^{\circ}\)C and 700 \({}^{\circ}\)C films, respectively. Figure 5: Telecom absorption characteristics of SiC films. **(A)** Comparison between \(E_{\rm g}+E_{\rm t}\) and \(E_{\rm 0t}\) values extracted from the CL model and TL/CL models, respectively. **(B)** Absorption coefficient at 1550 nm calculated using the CL and CU models for all AD and annealed samples, which shows all absorption values are below \(\sim\)10\({}^{3}\) cm\({}^{-1}\). **(C)** **(i)** Resonant PLE spectra across the telecom C-band of the 650 \({}^{\circ}\)C AD, 700 \({}^{\circ}\)C AD, and 700 \({}^{\circ}\)C A2 SiC films, along with SiO\({}_{2}\) as a reference. PLE intensities are consistent with SE-derived absorption trends. Intensity mappings over 5 \(\times\) 5 \(\upmu\)m\({}^{2}\) regions for the **(ii)** 650 \({}^{\circ}\)C and (iii) 700 \({}^{\circ}\)C AD samples demonstrate spatial uniformity of the results. **(D)** Relative comparison of \(E_{\rm u}\) extracted from the CU and CL models for AD and annealed samples. Symbol size reflects the associated error (10\({}^{-4}\)). **(E)** Correlation between \(E_{\rm u}\) values and the FWHM of the Si-C peak (\(\sim\)790 cm\({}^{-1}\)) from FTIR analysis of **(i)** 650\({}^{\circ}\)C and **(ii)** 700\({}^{\circ}\)C SiC films. **(F)** Comparison of figures of merit (FOMs) from this work with the best reported values in the literature. Amorphous covalent materials typically exhibit two types of disorder: bond angle disorder, associated with the inherent variability of the atomic structure, and compositional disorder, related to deviation from the ideal coordination. In the case of stoichiometric a-SiC, the latter may be manifested with the presence of topological defects (e.g., undercoordinated C and Si defects), as well as of homonuclear and heteronuclear bonding configurations, such as Si-Si, C-C, C=C, Si-H, and C-H [60; 61]. These bonding configurations may introduce defects and localized states within the optical gap, leading to enhanced optical absorption below the band edge, even in low concentrations (e.g., below the XPS and FTIR detection limit) (Figure S2i). The Urbach energy \(E_{u}\), extracted from both the CL and CU models, quantifies the exponential absorption tail below the band edge, which arises from disorder and/or defect-related states in the material, illustrated in the inset of Figure 4A.