Can anybody know how to get the band gap from the UV-Vis-NIR spectrum?
For most of semiconductors, the UV-Vis-NIR spectrum has one absorption peak; so I can calculate the band gap based on a N or P type semiconductor. I don't know how to calculate the band gap possessing two absorption peak. And what is means for the two peaks?
The possibility is- your material does not only contain what you think it contains. It is normal to form alloys of different elements in your thin-film. Moreover, contesting phases of different composites may also form multiple absorption point in UV-Vis measurements. You did not mention which material were you testing and what were the types and conditions of the fabrication, so it is not clearly possible to give you an explanation but I can share the below paper of mine where I myself have noticed multiple band-gap points due to the alloying/doping effect. Take a look at the section 3.6.1 for some possible explanations.
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Hi,
Actually it is very simple if the sample has 2 distinct absorption peaks. Follow 1240/lambda = band gap. If you do not have proper peak, use Tauc plot or kubelka munk plot. Use "n" properly for direct or indirect band gaps. See two papers (attached)...Best wishes
SD
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