Kelvin Probe

The Kelvin probe system allows precise measurement of work function of different semiconducting and conducting materials with high precision and accuracy

Net price: 25
Gross price (with tax) 30.75
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The Kelvin probe system allows precise measurement of work function of different semiconducting and conducting materials with high precision and accuracy.

The non-contact measurement involves oscillating capacitor, one electrode of which is a specimen, the other is oscillating reference electrode made of gold grid. Thus, measured value is referenced to the workfunction of gold (5.1 eV). Resolution of the measurement can reach 0.1 meV with sufficiently long integration time. The Kelvin probe system can be used in various type of surface studies, including: corrosion, adsorption/desorption, surface charging, catalytic activity and others.

For convenience, the probe is equipped with laser pointer and digital microscope. The motorized vertical positioning system allows reproducible of the reference electrode at the same distance from the specimen’s surface (with accuracy of 50 um). X-Y positioning can be installed as an option. The system is also equipped with wide-band light guide that can be coupled with digitally-controlled monochromator and high pressure xenon arc lamp. The wavelength range from 300 to 1000 nm can be used for continuous or pulsed sample illumination. This configuration allows measurement of the workfunction and electrical charging of surfaces, surface photovoltage spectroscopy and other photophysical techniques with photovoltage resolution better than 5 mV (0.1 mV when long integration time is applied). The whole system is accommodated in grounded Faraday cage for reduction of electrical noise and the influence of stray light. This surface photovoltage spectrometer is an essential tool in investigation of photocatalysts, organic and inorganic semiconductors, solar cells and other photoactive materials and devices. With the help of this Kelvin probe/surface photovoltage spectrometer monitoring of photocorrosion of semiconductors, photodesorption and photocatalytic reactions in real time is also possible.



The device consists of an oscillating gold probe mounted on a firm stand with Z-axis motorized stage, electronic control units and a Faraday cage.

  • A sample is placed on manual or motorized XY-stage with motion range of 1.5 cm in either direction.
  • The probe is attached to a Z-stage that can place it at a desired distance from a sample.
  • A red laser pointer shows place where the probe will oscillate over during measurement .
  • A USB microscope and a white LED are helpful once the system is covered with a Faraday cage.
  • Light is delivered to the sample with liquid waveguide or optic fiber, so the possible EM interference from a light source is eliminated.
  • In idle run or during storege the fragile gold probe is homed into a protected space to prevent accidental damage.
  • The system is also equipped with the automatic sample hight sensor.


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Probe tip

Probe S from Besocke Delta Phi GmbH used in our Kelvin probe systems.

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Faraday’s cage

The entire probe is covered with a Faraday cage, shielding it from the environment.

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The parameters below are subject to change due to ongoing instrument development

Voltage range-5 V .. 5 V
Voltage measurement nominal resolution0.15 mV
Measurement technology2-channel lock-in amplifier
Sample holdertranslation stage X-Y, manual (default) or motorized
X-Y stage stroke15 mm x 15 mm
Tip typeAu mesh, dia. 2 mm
Tip Z positioningmotorized Z stage
Positioning with respect to a samplelight barrier
Tip Z positioning resolution10 µm
Spectral range for wave guides200 nm .. 2000 nm (depending on a waveguide)
Liquid waveguides selection (Lumatec)Wybór światłowodów Lumatec
Auxiliary sensorshumidity and temperature
Internal Faraday cage illuminationwhite LED
X-Y positioning aidlaser sample placement indicator
PC connectivityUSB 2.0
Size40 x 40 x 45 cm
Weight10 kg


exemplary results

The following result come from P. Kwolek and K. Szacilowski publication “Photoelectrochemistry of n-type BiOI”. The authors used our Kelvin probe system to explore the structure of surface states of BiOI and to confirm that material is an n-type semiconductor. The results relevant to the Kelvin probe have been highlighted yellow in the publication and to the photoelectric spectrometer blue.

Differential surface photovoltage spectrum of the BiOI sample deposited on ITO surface. Photovoltage is measured as a variation of the surface potential on pulsed illumination vs. gold grid reference electrode.

As described in the publication: “The surface photovoltage response [figure] is observed in the visible region of the spectrum. It also stays in a good agreement with the absorption spectrum, since the photovoltage diminishes at 700 nm, but NIR illumination within 700-1000 nm still produces weak response. When the sample is under illumination the Fermi level of electrons splits to two quasi levels – one for electrons and one for holes. For the n-type semiconductor, the quasi Fermi level of electrons is shifted towards more negative potential values than the Fermi level of electrons in the dark. Therefore, negative surface photovoltage values confirms, that the obtained material shows the n-type semiconducting properties. Furthermore, the NIR sub- bandgap illumination also results in noticeable charge separation, which involves excitation of iodide-based surface states.”

P. Kwolek and K. Szacilowski, “Photoelectrochemistry of n-type bismuth oxyiodide”, Electrochimica Acta 104 (2013), 448-453.

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Kelvin Probe
Net price: 25
Gross price (with tax) 30.75
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Gross price (with tax) 33.21
Net price: 25
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