Surface potential: cannot see anything

Marco Coisson posted on Tue, Apr 27 2021 5:57 AM

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Dear all,

I'm new to Kelvin probe (surface potential), so it's not surprising that I'm having trouble with this technique, but I'm running out of ideas and I'm looking for help.

We have a Multimode 8 Nanoscope V AFM, and I'm trying to make Kelvin probe using MESP-RC probes: I know they are not optimal, but the only probes that we have with a metallic coating are magnetic (as we normally do MFM).

I followed the instructions on the manual to set up a surface potential experiment, but whatever I do, and whatever sample I put in, I can't seem to be able to get any signal from KPM. I tried with very easy samples (metallic patterns on a substrate, either grounded or not), and with more complex ones (dried SDS on a metallic substrate), all I get in the "potential" channel (pass 2, retrace) is some noise but no contrast among regions that must be clearly different concerning their surface potential.

I was wondering what I could be doing wrong: I believe it's something really stupid, but I'm stuck and not getting anywhere.

Thanks for any suggestions and stay safe!

Marco