I was trying to determine the thickness of SAM's using ARXPS and was wondering if that is possible. I read few papers but could not get definitive way of doing so.
Well, there are people who do measure the thickness with XPS (see e.g. Article Film thickness measurements of SiO2 by XPS
, although I assume you already found that). However, I am not sure that the attenuation length is well-defined enough in potentially porous matter in order to yield a precise result. Do you know your surface roughness? If it is below 5nm, I would highly recommend using XRR, that should be available at most institutions.
Dear Dr. Rupak Thapa,
generally, I think you can try to use Angle-resolved XPS (ARXPS). It is a technique that varies with the emission at the electrons are collected, thereby enabling electron detection from different depths. ARXPS provides information on the thickness and composition of ultra-thin films. Such measurements are also non-destructive.
For further information, you can see at: https://xpssimplified.com/angle_resolve_xps.php
Of course, other alternative techniques that can also provide information on surface morphology (eg AFM) could provide useful information to develop a correct measurement method.
Best regards, Pierluigi Traverso
Thank you Jürgen Weippert . Yes, I found that and also noticed that almost all people talk about metallic oxide overlayers on metals for ARXPS.
Artur Braun ,Could you please send me any links or any ideas where I can find the mathematics to do so? I think I would even love to see the mathematics you used so I can have some idea that I can use.
Any help would be appreciated.
Hi,
some additional links:
1) AR-XPS see e.g. https://www.youtube.com/watch?v=RLv3-gr7etw.
2) Comparison of the peak inensity to the background, see e.g. http://www.quases.com/products/quases-tougaard/.
Both methods are used for depth analysis.
Best regards,
John
Hi,
It depends on the thickness of the SAM. Usually, XPS can measure around 5-15 nm of the topmost layer. AR-XPS is even more surface sensitive, i.e., it measures the top most 1-5 nm of the surface. The surface sensitivity will depend on surface composition and angle geometry of the measurement.
Dhruv Shah , My SAM thickness is sub nanometer. Does that mean I can measure thickness using ARXPS? If you have any method/mathematics could you please let me know. I would really appreciate it. Thanks
Wait, if you're in the sub-nanometer range, that menas your thickness can't be more than 2 monolayers, or is it even just one monolayer? If you're doing 2D-SAMs, an XPS thickness measurement is not the best tool and I highly recommend STM or AFM.
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