I have photoluminescence spectra of nanocomposites. And just now I ran into the problem of calculating the band gap of semiconductor materials using the Tauc method. I have never dealt with these spectra and processing methods before. I would appreciate any help and advice. Perhaps there is an automatic processing of the spectrum online?
Thank you all in advance! :)
Dear Spartak,
The Tauc plot uses the information from optical absorption based on a few assumptions from semiconductors (primarily 3D). It isn't compatible with PL in regards to the way it works, but in theory, the PL peak should be located at the bandgap predicted by the Tauc plot.
You should start by getting an optical absorption measurement of your sample.
The optical absorption from direct bandgap semiconductors should be proportional to the square root of the photon energy above the bandgap, while for indirect bandgap it should be proportional to the square of the photon energy above the bandgap.
In the case of a direct bandgap, if you plot the square of the absorption as a function of the photon energy, you'll get a linear behavior after the bandgap.
In an indirect bandgap, if you plot the sqrt of the absorption as a function of the photon energy, you'll get a linear behavior after the bandgap.
If you fit the points very close to the cutoff energy, you'll be able to extrapolate the bandgap based on the intersection with the photon energy axis.
Again, this should work in 3D crystals, to my knowledge, because that's where the procedure was derived.
One book that could help is the Optical properties of solids from Mark Fox.
Hope that helps.
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