I am simulating XRR data of sputtered Cr thin films deposited on glass substrates.
I have failed simulating the XRR data of one sample; the film is Cr 20 nm thick and in the simulation model I am considering a native oxide top layer of Cr(OH)3 around 3 nm thick.
Between 0,9-1,2 degrees I observe that two Kiessig fringes present a separation significantly higher compared to the rest. This is the only reflectogram that shows such feature and I haven't find information to correct my model in order to simulate it.
I am including an image of the reflectogram.
Thanks in advance!
Dear Jerson,
you might have a slight thickness gradient in your film(s); either in your 20nmCr film or in the 3nm oxide layer. If your system is not correctly adjusted you may see the sections of your sample diffently weighted as a function of the incident angle.
Dear Gerhard,
Thank you so much for you quick response.
Are you aware of any document that may help me to study this.
Dear Jerson,
another idea is comming up:
your "loss" of amplitude of the Kiessig fringes in the range 0,9 to 1,2° appears like the loss in amplitude in the beat phenomenon of the superposition of two waves having slightly different wavelengths. In addition the 'phase' of the two fringes around 1,2 and 1,4° seems to be flipped (pi-phase shift).
So please try to simulate a reflectogram of a sample which constists of two parts:
one part (50%) has a layer thickness of 20nm Cr including 3nm oxid layer and the other part (also 50%) having a laver thickness of e.g. 25nm Cr and a similar oxide layer.
When adding such reflectograms I would expect a beating of the Kiessig fringes.
Please try and see what will happen. You may also vary the thickness of 25nm going e.g. down to 15nm for example.
If you can create an almost fringe-free angular region, you may fit the exact thickness value of the second (half) part of your sample.
Please 'play' a little bit with the geometry in your simulations.
What happens if you change the thickness of your oxide layer? (e.g. going up to 5nm for example).
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