I have doped SnO2 with Fe and Cu. The XPS data shows both Cu and Sn peaks but Fe peaks are not present. Does it imply that the sample was not doped with Fe or there can be other reason for the supression of the Fe peak?
there may be some link with the content of Fe and the quantity of Fe in the sample you made for XPS test. or maybe you can increase the scanning times when you test the Fe element, which will improve the signal-to-noise ratio.
Dear Sandip, there may be a reasn if you do not have surface cleaning during the XPS, then do it after the one complete survey, then i think you will get fe peak. Surface cleaning should be in xps chamber with ion sputtering.
As mentioned previously, one reason would be the amount of iron below the detection limit of XPS. In XPS the signal mainly comes from a few atomic layer on the top surface. If iron atoms are below this analyzed zone, they are not detected in XPS. The surface cleanliness would contribute to this situation.
Hello Sandip,
As other colleagues already mentioned that you may have Fe dopping less than the detection limit of XPS or your film is not homogeneously doped theirfore you may need to sputter clean your surface.
There can also be posisbility that the intenisty of Sn3p3/2 shadows the Fe2p peaks. As the Fe2p peak intensity is supposed to be very week.
Chitta is perfectly right. The Sn3p3/2 comes at 715eV, almost the binding energy of Fe2p. So you cannot see it since the amount of Fe is certainly much smaller than that of Sn. You could try to search for the Fe3p at about 60eV, although the cross section with normal XPS is very low. Alternatively you could search for the Auger lines, these are very different for Sn and Fe. For example the Fe LMM lines are between 780 and 880eV (using Al-Ka), while the Sn MNN are at about 1050eV
Massimo and Chitta are completely right, look for the Auger! Perhaps with monochromatted AlKa You might have a chance to see the Fe 2p3/2 if you scan long enough and the sample is well prepared. The 3p level might be difficult as the Sn4s might be broad and Cu 3p, O2s will swamp the area.
You can try it with Hard x-ray electron spectroscopy on synchrotron radiation sources where you can get the information from the 30 to 40 nm down the surface. Otherwise ion itching can be done get the information down the surface.
Hi Christian: the good old (not so much) XPS school :-)
You are right for the 3p level.
Actually, measuring at the synchrotron would solve all the problems!
The Fe doped SnO2 compound will contain three elements, such as Fe, Sn and O. Accorind to this formula you have to get spectum data of Fe, Sn and O. According to your information you have got peaks or data for Sn3p3/2 and O1s. However, you did not get any peak for Fe2p. Have you collect XPS data for Fe2p? if you have collected Fe2p data please try to fit these data in xpspeak41 software. After fitting, if you do not get any peak, you will make sure that amount of Fe much smaller below the sensitivity or resolation limit of the XPS which can not detect XPS. Another way you could try to search for the Fe3p at about 60eV, although the cross section with normal XPS is very low. Alternatively you could search for the Auger lines, these are very different for Sn and Fe. For example the Fe LMM lines are between 780 and 880eV (using Al-Ka), while the Sn MNN are at about 1050eV. In primary case, you have fogot to doped or your Fe doping amount was so samll that could not affect on the doped into SnO2.
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