Dear researchers,
To calculate bandgap using Tauc relation from UV Abs data of thin-film samples, firstly we need to have Absorption coefficient which is calculated from
absorption coefficient (α) = 2.303 A/t, where (A) is absorbance and (t) is the thickness of the thin film.
In my case, I have dispersed nanowires in 10ml DI water and recorded the UV Abs. I am not sure, how can I proceed with further calculation and looking for expert suggestions and guidance.
Thanks in advance.
Dear Chandrasekar Sivakumar ;
Optical band gap and photo-absorption energy for colloidal nanoarrays can be calculated from the UV-visible on-set, as detailed in the fig. 8 a&b in the following reference;
Article Fabrication of Ultrathin CuO Nanowires Augmenting Oriented A...
Dear Mahmood H. M.
Thank you for your information. I will read the paper and hope to find a solution.
Dear researchers,
To calculate bandgap using Tauc relation from UV Abs data of thin-film samples, firstly we need to have Absorption coefficient which is calculated from
absorption coefficient (α) = 2.303 A/t, where (A) is absorbance and (t) is the thickness of the thin film.
Chandrasekar Sivakumar
Tauc used an equation in 1968 to calculate the absorption edges (bandgaps) of amorphous Ge and Si from their absorption data.
(αhν)γ=A(hν-Eg)
In this equation, α is the absorption coefficient, h is Planck’s constant, υ is the frequency of the incident photon, A is a proportionality constant (which is determined by the index of refraction, electron, and hole effective masses; however, it is usually taken as 1 for amorphous materials), and Eg is the bandgap energy. The important term is the exponent γ, which denotes the nature of the electronic transition, that is, when γ=2 it is a direct allowed transition, and when it is equal to 1/2, it is an indirect allowed transition. For γ=2/3 it is a direct forbidden transition, and for γ=1/3 an indirect forbidden transition. Typically, the allowed transitions dominate the basic absorption processes, giving either direct or indirect transitions.
Thus, the basic procedure for a Tauc analysis is to acquire optical absorbance data for a sample in question that spans a range of energies from below the bandgap transition to above it.
Plotting the (αhν)γ versus (hν) is a matter of testing γ=2 or γ=1/2 to compare which provides the better fit and thus identifies the correct transition type.
I have provided the Template file (Origin file) in the video description. Thanks
https://youtu.be/LLESVSsZmlg
Shahid Ali Thank you for your detailed answer to my question. Much appreciated.
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