Absorption coefficient can be used to make Tauc plot and tangent method
gives Tauc gap [ https://en.wikipedia.org/wiki/Tauc_plot ].
Optical gap is determined from the plot of epsilon2 (the imaginary part
of the dielectric function) using the tangent method.
To visualize what Xavier describes in the posts at
https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg08951.html
see for example Figure 7 in the article titled "Band Gap Determination
from Diffuse Reflectance Measurements of Irradiated Lead Borate Glass
System Doped with TiO2 by Using Diffuse Reflectance Technique" by S.
Ebraheem and A. El-Saied [
http://file.scirp.org/Html/8-7701026_31475.htm ]. This article also
describes how r might be determined for the Tauc plot.
On 3/7/2016 3:05 PM, said chibani wrote:
Dear Wien Users ,
how to determineoptical gapfromthe graph of opticalproperties ? is
determine from the graph of absorption coefficient? and how ?
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