I have two samples of same material coated on si substrates with different thinknesses? Can we compare the intensities of XRD patterns after normalization ?
Why not comparing the FWHM (full width at half of max.) of the XRd peaks? That is should be similar to comparing the peaks after normalazion but for XRD it is easier and more common and understandable if you give FWHM as you can compare it with the values from other groups in the literature. You can not compare intensities with the reports out there as it is very instrument and diffractometer alignment sensitive!
You should also consider that if the films are too thin, you see the a stronger peak broadening due to the finite crystal thickness. So, it is harder to judge about the films crystal quality if one of then or both are very thin and have a different thicknesses.
By the way, what do you like to know from your XRd? Maybe there some complementarity methods like spectroscopy or microscopic evaluations to give a more concrete answer.
I want to compare the differences in crystal quality of both films.
I know, its not possible to compare the integrated intensities with reports but we can compare the samples characterized from same machine.
I just want to make sure, the way I am doing normalisation is correct and crystallite size that I am calculating from Scherrer equation is right.
I am doing Normalisation by dividing intensity with thickness of film and then multiplying with thickness of thicker film among the two.
I also have confusion about scherrer equation. I am getting crystallite size greater than film thickness. As I ame using out of plane peaks to calculate crystallite size then it should never exceed film thickness, if it does then Scherrer equation is not valid for my analysis. Is it the case?
I think in this case other methods like ellipsometery and AFM will be better to give you the good results.
AFM is giving me good results. But issue is not to use many techniques to find the differences. I just want to make sure that the way I am doing XRD analysis is correct.
In that case I think you should compare the results obtained from two different techniques. Then by comparison you may find some good agreement between two techniques and that will be answer to your question.
You have to be careful.
First, I would just normalize the height of the x-ray diffraction pattern (sample measurement time) for both samples by the known film thickness.This is a normalization to the same amount of material (but not to the grain size).
Then, if the FWHM and thus the grain size of the samples is different, the thickness-normalized intensities should also differ. The reason is that the intensity of each grain is proportional to N^2 (because the intensity is proportional to the square of amplitude, and the amplitude of a grain is proportional to the number of atoms N in the grain) and therefore the intensity of thin films with larger grains is much larger.
with best regards
Prof. Hans,
Thank you very much for your response.
I have two thin films of same material. I am normalizing for same amount of material (as you advised). Intensity is different after normalization. That makes sense.
I also have confusion about Scherrer equation as it gives crystal thickness and values calculated form Scherrer euqation should not exceed from thickness of films but they are, is it possible?
Thanks
in your thin film you probably have columnar growth. For this, the Scherrer eqution is only a first approximation. Naturally, grains should not be larger than the film thickness, except the surface is enormous rough.
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