Can band gap of semiconductor be found by UV spectroscopy. I do know people find it by Tauc plot or kulbeka-munk model. But how reliable it is if the semiconductor is crystalline. I am in a notion these measurements are valid only for amorphous semiconductors but not for crystalline. I may be completely wrong. Pl clarify me if you have come across some solid arguments. Except UV-spectroscopy or PL what are the other measurements we can measure band gap? How reliable is to measure conductivity vs temperature to find band gap above room temperature?
Conductivity vs temperature is probably not a good method unless you have extremely good control over background impurities in your crystal. UV spectroscopy or PL is the simplest and pretty reliable.
I have got good values of band gap for undoped and doped samples using UV-Vis spectroscopy using both Tauc plot or Kulbeka-Munk equation for poly-crystalline materials (ZnO). Hence I would regard is as reliable. I don't have any idea of about conductivity vs temperature to find band gap. Best of luck.
Log(R) versus 1/T plots of films deposited at different substrate temperatures (Ts) gives band gap value.
Kubelka-Munk is also effective method.
Yes, u can estimate band gap using Brus equation.. This is an useful thing for estimating size also specially for semiconductor nanoparticles...
pls follow this article
http://www.chalcogen.ro/709_Baset.pdf
Hi.
I think for indirect band semiconductor, UV vis spectroscopy is not suitable. Electrical measurement is a good option that you can rely.
Hi Avishek,
That may not be true. Talc plot is established for direct and indirect band gap using UV-vis. Rather electrical measurement is always tricky since you do not know how much impurity you have in your system as Geetak mentioned in the above and that in turn affect your mobility and thus the difficulty in measurement of band gap as I suspect.
. However, my question was how about determination of bandgap for amorphous and crystalline semiconductor using UV-vis. The question remains still unanswered.
Hi Ankur
As reported in the attached literature it is expected that the crystalline phase will give you better result than the amorphous phase. I hope it will be helpful for you to draw the final conclusion.
The optical absorption spectra of a semiconductor thin filmcan be obtained using an UV-Vis double-beam spectrometer, The optical absorbance can be measured from these spectra.The band gap of a semiconductor material can be obtained from the absorbance measurements in the visible range using the Tauc method. The other way to obtain it using a PL.
To find gap energy value via electrical measurement of thin semiconductor films, you can use Hall measurement .....> conductivity vs measurement temperature (below room temperarure)
UV spectroscopy is useful for amorphous or cristalline thin semiconductor films: using double beam UV app we can find transmittance, reflectance and absorbance : optical absorption coefficient can be determined using furmula that involve R and T and the thikness of your film .....> tauc low is availble for direct and indirect Sc...the difference the plot used (Alpha*hnu)^2 vs hnu for direct gap sc.........band tail also can have a specific sign in the plot...
Quite informative to me. I think Mr. M. Nouiri's contribution is very lucid and objective.
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