Abstract
The polysilicon (poly-Si) in tunnel oxygen passivated contact (TOPCon) structures delivers outstanding passivation performance; nevertheless, it also introduces some level of parasitic absorption, particularly noticeable in the medium and long wavelength bands. Here, we synthesized carbon (C)-incorporated poly-Si by introducing carbon into poly-Si through the plasma enhanced chemical vapor deposition (PECVD) method, aiming to mitigate parasitic absorption. Our focus was on investigating the impact of parameters such as C content and annealing temperature on the optical properties of poly-Si, including the refractive index and extinction coefficient. Additionally, we calculated the free carrier absorption (FCA) through the reflectance and transmittance of the material. It is found that the FCA in the long wavelength band decreases with increasing C incorporating, while it increases with higher annealing temperature. Furthermore, simulations revealed that the parasitic absorption of C-incorporated poly-Si (with the CH4/SiH4 flows ratio of 3) in the back plane of TOPCon cells is approximately 0.38 mA/cm2 per 100 nm, less than 0.52 mA/cm2 per 100 nm from the conventional poly-Si. Therefore, the results show the advantages of C-incorporated poly-Si in optical properties.
Published Version
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