If You do not have mica or hopg use silica wafer. If you do not have big silica wafer use 'pad' of AFM's tip construction. It is small, know it, but flat enough to work as substrate. If it is still not suitable for you try to use microscopic glass cover slips, but first check the roughness of surface.

Hi Hossein,

The classical substrates for AFM are mica and oriented pyrolytic graphite. It is very simple to do an atomic smooth and ideal clean surface for these materials by a simple adhesive tape. Graphite is conductive and it is possible to use it for experiments with conductive probes.

You can use FTO glass slides, but I am not sure that it is a good idea. Glass doesn't have an atomic smooth surface and it can be contaminated. It is not simple task to do ideal clean and smooth glass surface.

We use conventional electrotechnical mica as substrate for AFM. It is dozen times cheaper than special mica discs for AFM. We just cut off a piece of mica by a knife and stick it to glass by a double-sided adhesive tape. Then we make a fresh cleavage of mica (stick and detach adhesive tape) and use it as substrate for AFM. There aren't any differences in comparison with expensive special AFM mica discs.  

Good luck!        

Thank you denis. Your answer was complete and detailed. But Mica or HOPG is not accessible to me. So i am going to use another substrate like FTO. But i have no experiment about doing this task.

I completely agree with Denis. If you go with FTO glass your roughness might be so big that the AFM will not be able to properly track the surface. Please also take into consideration the maximum vertical resolution of the AFM you'll be using. 

Best,

Daniel

If You do not have mica or hopg use silica wafer. If you do not have big silica wafer use 'pad' of AFM's tip construction. It is small, know it, but flat enough to work as substrate. If it is still not suitable for you try to use microscopic glass cover slips, but first check the roughness of surface.

Dear Janusz, using the probe holder of the AFM as an alternative Si wafer is a great idea. Thanks!

@Zhuangqun Huang, soft and sticky? Why? It is just Si or Si3N4 chip with smooth surface. Did you mean a contamination? 

We have used Si chips from AFM's probes as substrates. They were Ok. For cleaning of surface it is enough just dip it to Piranha solution for several minutes and rinse with clean water before using.    

  ·

Zhuangqun Huang , if Im not wrong Si is not kind of soft material. Are we talking about the same stuff? If so, this part of tip is flat and few years ago I made ('burn') my initials on it...

EDITED: after FIB (the gallium ions deposition all the time) the surface is still not bad - see jpgs.

Dear Hossein,

As the other people mentioned, FTO glass might not be the best one due to its native roughness as compared to the height of your graphene flakes in suspension. 

Broken si chips might be an smart solution for that. The main issue for that is to find the appropiate concentration of your graphene solution to have the graphene flakes dispersed all over the surface and not in aggregates.I can provide you some info about that if you wish.

Another option would be to use FTO glass and measure not just the topography but other electrical properties like Current/Resistance or  Surface potential with more advanced modes like ResiScope mode or Kelvin Probe mode.

thanks to all of you dear scientists.