If you want to use DRS analysis to calculate band gap, thickness of your sample is not necessary in this calculation.

The Kubelka-Munk function (F(R)) which is defined in terms of reluctance (R) was used to calculate band gap. The attached published article explains the details of this calculation (section 3.3: UV-visible absorption study).

Best regards...

Hi Ebrahim:

For the Tauc (pronounced “tautz”) plot, plot your absorbance data with hv (photon energy) on the x-axis and (epsilon*hv)^n on the y-axis, where epsilon is the absorption coefficient for the material and n is typically 1/2 for direct band-gap materials. If you know your film thickness, you can calculate out the absorption coefficient. Remember, you’ll have to translate your wavenumbers into energy before making the plot.

When plotted in this way, you should see the data hugging the x-axis until absorption begins, then the trace should turn upward and describe a relatively straight line. If you extrapolate this straight line (linear) region backwards toward the x-axis, the intercept will be an approximation of the band gap of the material.

For a (very) short discussion of this, visit the Wikipedia page on “Tauc plot”. There, you’ll find an example plot and a number of references you might find helpful.

If you want to use DRS analysis to calculate band gap, thickness of your sample is not necessary in this calculation.

The Kubelka-Munk function (F(R)) which is defined in terms of reluctance (R) was used to calculate band gap. The attached published article explains the details of this calculation (section 3.3: UV-visible absorption study).

Best regards...

Just be sure to study and understand the concept of the Kubelka-Munk formalism, and make sure that the inherent simplifications do not spoil your result.

Hi Ebrahim.

I recommend this review:

Lopez, R.; Gomez, R., Band-gap energy estimation from diffuse reflectance measurements on sol-gel and commercial TiO2: a comparative study. Journal of Sol-Gel Science and Technology 2012, 61 (1), 1-7.

Hi Ebrahim, I would suggest you to read these papers.

1.Measurements of Band Gap in Compound Semiconductors:Band Gap Determination from Diffuse Reflectance Spectra, Spectrophotometric Analysis, Shimadzu Application News, No.A428.

2.Band Gap Measurement of Indium Tin Oxide by Transmission Spectroscopy, by Matthias Mengel

3.R. Gómez et. al., "Effect of sulfation on the photoactivity of TiO2

sol–gel derived catalysts",Journal of Molecular Catalysis A: Chemical 193 (2003) 217–226.

4. W. H. Strehlow, E. L. Cook,"Compilation of energy bandgaps in elemental and binary compound semiconductors and insulators", J. Phys. Chem. Ref. Data, Vol 2, No 1, 1973.

Thanks a lot for your Guidance and Support

Kunal Mondal

if you have PDF of above mentioned papers then kindly inbox me or upload here

thanks