Band gap finding from UV-Visible data. Some people are using Y-axis as (α*hν)^1/2 and some people are using α^2 instead, i.e. α is function of hν .α(hν). X-axis is same hν (eV).
Both are correct but applies to different types of semiconductors. ^2 is for direct band gap semiconductor, while ^1/2 is for indirect band gap semiconductor.just find out your material belongs to which category.
And if your material is not completely new, then you can find whether its direct band gap or indirect band gap from E vs k graphs from literature. otherwise you have to carry out a theoretical study on your material to find out the E vs k curves(dispersion curves)
thank you Madhusmita sahoo. yes you are absolutely right but some journals showing (α*hν) ^m (where m depends on direct or indirect bandgap) at y-axis i.e. here α multiplied by hν but according to Jacques I. Pankove ( optical processes in semiconductors book page number 40, equation 3-14) , α is a function of hν.......which one we have to follow to find out band gap ?? this is my actual question..
We normally do it with (α*hν) ^m, i don't have the book that u mentioned but i feel if its only α also the other factors would have been taken care of in the mathematical consideration.
J. I. Pankove and P. Aigrain, Phys. 126, 956 (1962).....
please refer this journal...hope you can understand my problem...
Madhusmita Sahoo please find the attached file.......y-axis is (alpha)^1/2 or ^2 not in (α*hν) ^1/2 or ^2................................................i have found lot of papers for band gap calculation y-axis is a (α*hν) ^1/2 or ^2.......which one i have to follow
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