I am using Bruker diamension icon. I would like to measure the surface roughness of ultra-smooth quartz substrate. I tried with Scansyst mode as well as contact mode. Scansyst shows a high force curve in which the measurement stops in between. contact mode, no surface is obtained. The tip is working fine since I tried multiple samples after that and every measurement came well.
Dear Dr. Muhammed Razi P ,
I suggest you to have a look at the following documents:
-Topography and surface roughness measurements by Nanosurf
Available at: https://www.nanosurf.com/en/support/afm-modes-overview/topography-and-surface-roughness-measurements
and
-Advanced measurement and diagnosis of the effect on the underlayer roughness for industrial standard metrology
Kim, JH., Moon, S., Kim, JW. et al.
Sci Rep 9, 1018 (2019).
Available at: https://www.nature.com/articles/s41598-018-36991-z
My best regards, Pierluigi Traverso.
Have you also tried tapping mode? You may have to play a bit with the amplitude setpoint and the gain but if you're in the 1-2 nm rrms range that should work fine.
Hi Dr. Razi,
Something that is very important in AFM is the tip quality and condition, and that worries me a lot in your question is that you say you have measured many samples with the tip and you think the tip is working well.
In my opinion the approach itself is a problem. The tips as you know are very delicate and it's not advisable to use them to perform many measurements on many different samples (with the same tip). The reason is simple, the probability that the end of the tip will break, wear, dirty or degenerate in any way is very high the more samples you measure with them.
Also, I would like to clarify an small inaccuracy, Scansyst is not (itself) a measurement mode, is an automatic image optimization technology that allows you to perform measurements in Peak Force Tapping Mode with a high level of automation. Peak Force tapping is an ultra low contact force mode (pN-Force). This mode should theoretically allow you to measure very delicate materials such as biological samples but also very hard materials such as quartz.
I would recommend that you try to put a new tip first.
You can also try to make relatively small scans that is 1 umx1um (x, y), since the roughness is very low, the system will be more comfortable if you reduce the size of measurements to have more sensitivity for such low roughness.
On the other hand, you can also reduce the cantilever Z displacement (the software allow to do that). Since the surface is very flat, the cantilever does not need to make large Z-travels, so reducing the Z-displacement of the cantilever will help to have more sensitivity in very flat topographies.
Hope it helps
The comments by C. Serra-Rodríguez are very good. Indeed, the top of a tip may break off over the course of many measurements and create nasty artifacts without giving an actual tip crash error.
Muhammed Razi P
Yes I know some free software to process the AFM image, that allow to improve the image (remove strikes, flatten, noise reduction).
We use in the lab two free platforms:
1) Gwyddion – Free SPM (AFM, SNOM/NSOM, STM, MFM, …) data analysis software
http://gwyddion.net/
2) An interesting "free on line processing software" (valid for AFM images). There are options to "correct" the AFM images. Include Standard operators and Specific AFM operators for image processing.
Supported many many file formats
https://www.profilmonline.com/
I hope this helps
Thank you for your replay @ C. Serra-Rodríguez. Thanks for all for a nice dscussion.
I would use contact mode for such hard and flat material as quartz, following the measurement with power spectrum analysis. Tapping mode might be too insensitive for rms in the range of 1-2 nm. ~10 Ang.
Since your substrate quartz is an insulator, there will be alot of electrostatic charge on the surface and they will dominate competely over van der Waals force between tip and sample. This makes problem to the topography measurement. To avoid the electrostatic force, the sample surface should be electrically grounded by applying a conducting tape. If you do a simple f-d curve, you can findout whether electrostatic force present or not.
Both contact & semi-contact mode should work. If you use semi-contact mode, you should use a small tip osilation amplitude & high gain to increase sensitivity, as already suggested by many others.
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