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I am curious about a common artifact seen in Contact mode measured in conjunction with CAFM bias to a CdTe sample. These lateral lines seem to be independent of any settings I have control over. They appear in both the topography and the CAFM map. I assumed they were a function of lateral forces against the probe, but I seem to have no control over whether they exist or not. Has anyone seen this and know the cause/solution? This is on a Dimension 3100 with a TUNA extension module. Thanks! Jeremy
Hi Jeremy,
Did you try scanning the sample in tapping (w/out the CAFM) to compare?
Stefan
Yes, tapping mode corrects this issue (another reason I would think it is lateral/friction forces), unfortunately CAFM is not available on this model in tapping mode.
So there is very little you can do except live with it and to take a tapping mode image if clean topography is required. If torsional mode is available to you you could try that as it would mitigate the issue you are having.
We do have a new TUNA module that works great with PeakForce Tapping and it compatible with MM8 or ICON. If you have access to one of these system give it a shot!
Hello Jeremy,
I don't know much about TUNA, but is scanning with a 90 degree angle an option? If it is related to lateral forces, the lines shout increase I expect, if they are the same I expect it to be sample related? But perhaps Stefan can comment on this......
Joop
TUNA measures simply a (small) current from tip to sample. That should be rather independent of the scan direction. So if 90 degrees give you a slightly better topographic image go for it. I am, however, afraid that Jeremy encountered just a basic limitation of contact mode. Hence the idea avoiding that by going to e.g. torsional mode. The phenomena that Jeremy oberserves was actualy our motiviation for combining PeakForce Tapping and TUNA. It becomes even more difficult if you try scanning e.g. carbon nanotubes in conventional TUA with contact mode but is really easy and artifact free using PeakForce TUNA. Again, if you dont have PeakForce available trying torsional resonance mode already helps quite a bit even though it is a bit slow.
Thanks for the clarity Stefan. I assumed as much but thought I would spend some time trying to mitigate. I'm not familiar with torsional resonance - is this a seperate mode availabe to some applications?
Jeremy, torsional resonance can be used for stand-alone imaging or in a maybe more productive combination with TUNA. You check your TUNA tipholder. If it says something like "Extended TR TUNA" you have the correct tip holder. If it just says "Extended TUNA" without the TR you don't.
Thanks Stefan, I seem to have the correct tip holder. However, I still do not know how to apply this mode. There is nothing in the D3100 manual about Torsional Mode. Also, are there any probes that may be better at reducing these effects? Perhaps a broader tip such as the diamond doped or the SCM-PIC with a lower spring constant? Any additional input you may have would be helpful.
Thanks,
Jeremy
On your D3100 system should be a "manuals" directory. This contains technical support notes for using torsional mode for Nanoscope version 5,6, and 7. If you email me at: stefan.kaemmer@bruker-nano.com I can email you the version 7 guidelines and a quickstart guide. If you have an older SW version please contact Bruker customer support and they can hook you up with the documentation.
For your contact mode imaging there are indeed various choices for tips. You pointed out the diamond coated tips. They are indeed very robust, exhibit good conductivity but suffer a bit from the shape of the diamond coating for topgraphic imaging. SCM-PIT is of reasonable low spring constant (1-5 N/m) but also allows for tapping operation for e.g. EFM imaging. The SCM-PIC are quite soft and thus gentle. Both PIC and PIT ar Pt/Ir coated. One has to select the probe depending on the problem at hand. E.g. on some sample a reasonably high force has to be excerted to actyually get a current. The soft PIC probes would not be suitable for that. If your sample on the other hand is quite fragile, the PICs might be your choice. Check brukerafmprobes.com for more detailled information.
Good luck,