Surface Potential Detection

Bruker provides several methods for surface potential imaging:

• Lift Mode Surface Potential Imaging (AM-KPFM) (aka AM-KPFM) measures the effective surface voltage of the sample by adjusting the voltage on the tip so that it feels a minimum electric force from the sample. (In this state, the voltage on the tip and sample is the same.) Samples for surface potential measurements should have an equivalent surface voltage of less than ±10 V, and operation is easiest for voltage ranges of ±5 V. The noise level of this technique is typically 10 mV. Samples may consist of conducting and nonconducting regions, but the conducting regions should not be passivated. Samples with regions of different materials will also show contrast due to contact potential differences. Quantitative voltage measurements can be made of the relative voltages within a single image.
• PeakForce KPFM-AM Imaging combines the Surface Potential Detection mode with Bruker's proprietary Peak Force Tapping Mode.
• FM-KPFM Imaging uses a frequency modulation technique to measure surface potential. FM-KPFM is generally more accurate and has higher spatial resolution than AM-KPFM.
• PeakForce KPFM Imaging combines FM-KPFM Imaging with Bruker's proprietary Peak Force Tapping Mode, combining the benefits of both modes.
• PeakForce KPFM-HV Imaging combines Bruker's proprietary Peak Force Tapping Mode with an AC technique that enables measurement of surface potentials up to approximately ±200 V.

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