Hello Duong

In some cases, when we plot the Tauc curve from DRS data, we notice that two different lines can be fitted to distinct regions of the plot. This usually happens due to the presence of different optical transitions (direct or indirect) or intermediate defect-related states. To identify the correct band gap, we choose the line that fits the most linear part of the curve and shows better statistical agreement, specifically, a higher R² value. Generally, the line that intersects the energy axis at a higher value corresponds to the intrinsic band gap of the material.

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According to Tauc's law, the energy band gap corresponds to the intercept of the extrapolated linear portion of the curve ( corresponding to the asymptote of the curve ). In this work, Eg is around 2.75 eV

Aida Ben Jazia Kharrat thanks so much, need to prove it?

Atefeh Kiani thanks so much, need to prove it?