KFM Kelvin Probe Force Microscopy

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KFM (Kelvin Probe Force Microscopy)

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KFM?

• Kelvin Probe Force Microscopy
• To measure the surface potential distribution
  during the DFM
• Creates a electric field of D.C. and A.C. between
  the cantilever and the sample and using the
  static electric force at that time.
• The surface potential of a microscopic region of
  the sample is detected from the cantilever
  vibration and imaging is performed

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History

• 1898 - vibrating capacitor plates work
  function, surface portentials
• 1988 - 40µm resolution Bäumgartner
• 50nm - attractive force microscope Martin et
  al.
• KFM contact potential variations Weaver
  Abraham
• Frequency modulation (FM) Kitamura Iwatsuki
• Amplitude modulation (AM)

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Force

• F Fvdw Fvib Fes
• Fvdw short range force
• Fes long range force
• ? lift mode

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Two scan modes
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Frequency modulation (FM) mode

• The oscillation of the frequency shift at ? is
  measured
• Gradient of the electrostatic force

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(No Transcript)
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Amplitude modulation (AM) mode

• Amplitude of the cantilever oscillation at ? is
  measured
• Electrostatic force
• (Surface potential imaging)

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Scheme
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Surface Image
Surface Potential
Surface Potential Image
F Fvdw Fvib Fes
Fes
Fvdw van der Waals force Fvib vibration
force Fes Electrostatic force
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Measurement

• KFM holder
• Active trace mode
• Fmax 40 KHz