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Hello Friends,
I have an unusual phenomenon while using conductive AFM (Dimension 3100) with interleave mode.
In the main scan path, only the topographic information was collected in contact mode without bias. In the second scan path (interleave mode), the tip repeated the topographic route collected from the main scan path, but with a bias applied to the sample(the sample was electrically connected to the sample chuck), in order to the collect the current signal.
In the beginning, I realized the topographic image was disturbed by the corresponding current signal even under interleave mode! Therefore, I used an additional channel to record the current signal in the main scan path (the other 2 channels are ´Height´ of main path, and ´Current´ of interleave path). Theoretically, there should have no current signal in the main scan path because the bias is only applied in the interleave path. However, the result shows the current signal also exists in the main path (but with much less scale).
I will post the picture tomorrow. Hope any expert here can help me.
Thank you very much!
Solong
Topographic Image
Corresponding current image in Main Scan Path
Corresponding current image in Interleave Scan Path
And this is the screenshot of the measurement parameters
Solong,
Although you set sample bias to 0 mV on the main scan, there may be some offset on the sample bias line which can be up to 20 mV, this is sufficient to get the current flowing.
You can measure the voltage on the sample chuck versus a ground, for instance, the dove-tail where the AFM head is mounted, to see exactly how much offset is present. You can apply a bias to negate this offset.
Best
Chunzeng
Hello Chunzeng,
Thank you very much for your reply!
I have checked the offset of the sample chuck versus a ground Vs-g =5mV; the offset of the sample chuck versus the dove-tail Vs-d =2mV. Therefore, I don´t think these offsets are able to cause a noticeable current signal in the main scan path.
I am thinking about the work function difference between the tip and the sample. I use SCM-PIT tip, which is coating with Pt (work function = 5.63 eV)and Ir. The conductive part of my sample is Ag(work function = 4.26 eV). What do you think the work function difference of 1.4 eV between Pt and Ag is attributed to the current signal in the main scan path?
Thanks again!
Best,