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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
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Isma, Most likely Bruker's Universal Bipotentiostat would work, which has more gain stages. The difficulty is, if there is any problem, it can be hard to work out as it requires Agilent and Bruker to solve the problem, if any, together. Sorry for not being more definitive. Chunzeng
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Isma, It depends on your STM system whether an external bipotentiostat would work to support all the functions, seemlessly. May I have the model of your STM and controller? Thanks Chunzeng Li Applications Scientist Nano Surfaces Division, Bruker
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Here are my answers to your questions: The same bias voltage is maintained for both trace and retrace, so you can select data on either trace or retrace. When using false engage, you must set both sample bias and test bias to the same value that's better to be bigger than 500 mV, this is essential to get a proper calibration. There is usus. a bigger
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Sandeep, SCM data quantification has been attempted, but not with widespread success. Here is a quote from "Scanning Probe Microscopy" Edited by Sergei Kalinin: http://www.ebooks.com/302033/scanning-probe-microscopy/kalinin-sergei-gruverman-alexei/ I.3. Scanning Capacitance Microscopy for Electrical Characterization of Semiconductors and Dielectrics
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Hi Solong, 1. How do you quantify the CAFM noise? It is peak-to-peak or RMS? 2. A couple of things to be aware of: While the sample chuck is conductive on the macroscopic scale, it may not be so on the microscale/nanoscale, oxide may be present. The oxide can have different I-V characteristics than what you expect of an ideal conductor. Make sure the
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Hi Solong, The noise level of the module is best charicterized when the tip is off the surface. But anyway, the noise should not go up to 500 pA; is it really noise or signal. can you send me a screenshot or the original file for me to take a close look? Thanks Chunzeng Li Applicaiton Scientist Nano Surfaces Division, bruker chunzeng.li@bruker-nano
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Hello Solong, The potential value may change somewhat with lift heihgt, but should not jump/alternate at all. It is likely the phase is not set properly in the first place. Please set the phase per the procedure outlined in a previous post, I expect the problem to go away. Best Chunzeng Application Scientist Nan
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As you mentioned, using the right phase for surface potential measurement is critical. Here is a procedure you can follow to find the proper phase, I can be more specific if I know which version of software you are using (a screenshot of the UI is ideal, you can send to my email): Turn Surface Potential Feedback off. If this option is not available
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No problem. It is not entirely your fault, we could have set the default to none. Best Chunzeng