Considerations about the determination of optical bandgap from diffuse reflectance spectroscopy using the tauc plot

The optical diffuse reflectance data of a semiconductor material is usually converted into the Kubelka–Munk function before proceeding to process the conventional Tauc’s plot from which optical bandgap energy can be determined. Firstly, it is conventional/ customary to convert the percentage reflectance ( R_∞ ( R_∞ ) that range between 0 and 1 before processing the Tauc’s plot. Secondly, the Kubelka–Munk function is usually multiplied by the incident photon energy, hv , to produce an all-elements/ comprehensive Tauc’s plot. Literature is scarce to convincingly demonstrate that a correct bandgap value can, alternatively be obtained from the Tauc’s plot that is derived directly from the ( R_∞ ( R_∞ . Also, publication is rarely available to demonstrate that a proper bandgap value can be determined without having to multiply the Kubelka–Munk function by the term hv . The present investigation shows diminutive differences in the bandgap values estimated from the R_∞ ( R_∞ -based Tauc’s plots. This suggests that either of the methods can be employed for a precise bandgap estimate. A comparison between the magnitudes of the bandgap energies determined from the comprehensive Tauc’s plot and when the Kubelka–Munk function is not multiplied by hv reveals insignificant differences in the estimated values. This suggests that either of the two methods can be employed to obtain a reliable bandgap for direct and indirect optical gap semiconductors.