For running Peak-force TUNA and C-AFM, we need a substrate which is conductive enough to pass the current to the sample; however, it should not be too conductive to saturate the current. What do you suggest as a proper substrate?
Thank you so much for your help in advance.
I have also used Au Si wafer (2nm Cr sticking layer, 50 nm Au - deposited via sputter coating). Just make sure you use a conductive tape to electrically connect the gold to the base.
Alternatively, HOPG can be used if you need a flatter substrate.
I have rarely had an issue with the substrate being too conductive. You can always just use a lower potential for current mapping.
I think au or pt coated SLG, ITO, Al doped ZnO can be a good possibility.
Thank you dear Qijin, Cameron, Chetan, and Li.
The issue is that the highest current that Peakforce TUNA can measure is 1 uA. Hence why most commonly used conductive substrate ( such as HOPG, gold,...) cannot be used for it.
Best,
Dr. M.Reza Khoshi,
Will graphene sheet is not the better option in your case. Even by process of doping you can change the band gap and hence change the conductivity of the required substrate.
Hi,
If the surface of interest or structures on the surface could be connected to ground, your PF TUNA measurements should normally work.
As an example think of carbon nanotubes on silicon oxide. if the nanotubes are electrically connected to an electrode that you ground, PF TUNA will give you the conductivity of these nanostructures. Current though will then flow through the nanotubes rather than vertically through the silicon oxide substrate.
So I would say, as long as you can electrically ground the part of interest on the surface of your sample, the substrate should not matter.
You could check this application note in the attached link that shows the example that I mentioned in figure 11.
good luck :)
K2
https://www.bruker.com/fileadmin/user_upload/8-PDF-Docs/SurfaceAnalysis/AFM/ApplicationNotes/Simultaneous_Electrical_and_Mechanical_Property_Mapping_at_the_Nanoscale_with_PeakForce_TUNA_AFM_AN132.pdf
Hi I have used Peak force TUNA. For films/samples that are semiconducting/insulating you can just use any conducting substrate get them connected to the AFM metallic chuck through conducting tape/silver paste.
For samples that are very conducting (irrespective of substrates) i prefer to isolate the substrate from the chuck by using a tape (kapton) on the chuck and place sample over it and later have the sample connected through a resistor to the AFM metallic chuck to make sure we dont have the current saturated.
See if this works for you.
I generally work only on semiconductor/di-electric films so I am sure with these..but for conductive samples the above method may work...though the idea is crude you could build on that..
Hope it helpsss..
Cheers,
How smooth should a sample be before taking Bruker's PFTUNA measurements?
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