In the Tauc relation:
(hνα)1/n = A(hν - Eg)
How does n vary for the glass system? Do the direct or indirect band gaps give the same value or different? What would be the choice of n?
In a Tauc plot, you plot (hνα)n vs. (hν), where n is 1/3,1/2, 2/3 or 2 for indirect forbidden, indirect allowed, direct forbidden and direct allowed, respectively. α is the absorption coefficient of your layer and hν the photon energy. When you extrapolate the linear regime of the plot to the abscissa (x-axis), you obtain the optical band-gap of the corresponding transition. If the direct transition is found at a lower transition energy than the indirect one, you have a direct material.
However, other methods such as ARPES would be better suitable for determining the electronic structure, I think.
In a Tauc plot, you plot (hνα)n vs. (hν), where n is 1/3,1/2, 2/3 or 2 for indirect forbidden, indirect allowed, direct forbidden and direct allowed, respectively. α is the absorption coefficient of your layer and hν the photon energy. When you extrapolate the linear regime of the plot to the abscissa (x-axis), you obtain the optical band-gap of the corresponding transition. If the direct transition is found at a lower transition energy than the indirect one, you have a direct material.
However, other methods such as ARPES would be better suitable for determining the electronic structure, I think.
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