I have prepared CuS covellite phase and TiO2 anatase phase. Suggests some references how to calculate direct band gap or indirect band gap semiconductor.
Hi Manju! Guess you have powder samples. Spread the powder on a black surface. You may use some black adhesive tape etc or any accessory of the spectrometer that can be used for powder samples. Use UV-Vis diffuse reflectance spectoscopy. Obtain the data.Later on convert wavelength on X axis in to enenrgy (eV) by 1240/wavelength (nm).From Y-axis of the spectrum convert the data in to Kubelka Munk function i.e Kubelka Munk K.B (R)= {(1-R)^2}/{2R} where R is the diffuse reflectance. Lately plot: Y axis (K.B) ^2 vs Energy (eV) and intercept the most linear region on the X-axis that will give you direct bandgap. Similarly, for indirect bangap, plot (K.B)^1/2 on Y axis vs Energy (eV), take the most linear region of the graph make the same intercept which will be indirect bandgap. Hope it helps you.
Hi Manju! Guess you have powder samples. Spread the powder on a black surface. You may use some black adhesive tape etc or any accessory of the spectrometer that can be used for powder samples. Use UV-Vis diffuse reflectance spectoscopy. Obtain the data.Later on convert wavelength on X axis in to enenrgy (eV) by 1240/wavelength (nm).From Y-axis of the spectrum convert the data in to Kubelka Munk function i.e Kubelka Munk K.B (R)= {(1-R)^2}/{2R} where R is the diffuse reflectance. Lately plot: Y axis (K.B) ^2 vs Energy (eV) and intercept the most linear region on the X-axis that will give you direct bandgap. Similarly, for indirect bangap, plot (K.B)^1/2 on Y axis vs Energy (eV), take the most linear region of the graph make the same intercept which will be indirect bandgap. Hope it helps you.
Hi Manjunath,
You can alternatively follow Tauc's equation too. You can follow this paper where Kubelka-Munk plot as well as Tauc's plot has been detailed.
http://www.msri.org/people/staff/levy/files/ToPrint/murphy-filmbandgaps.pdf
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