The Scanning Kelvin Probe allows to measure CPD (Contact Potential Difference) value and evaluate a work function of semiconducting and conducting materials. The measurements may be performed not only in a single point of a sample surface but the whole surface may be scanned.
Measurements of work function is particularly useful in semiconductor physics as it provides the position of Fermi level of examined material.
The Kelvin Probe equipped with the light source makes it possible to examine surface states of electrons of the sample. Surface states of electrons play significant role in the electric charge transfer, which is especially important for photovoltaic materials and in photoelectrochemistry.
Possibility of scanning the sample surface and to examine its electrical properties enables precise assessment of the quality of the material, and its homogeneity. The series of data gathered during the experiment may be used to evaluate work function more precisely.
Scanning Kelvin Probe allows to specify the electrostatic charge distribution on the examined sample surface – including dielectrics! (up to several kV). The measurement method applied and the design of the instrument makes the instrument unique and peerless in testing charged dielectric surfaces. The system enables to specify the electrostatic charge (up to several kV!) distribution on the sample surface.
The instrument consists of the probe on the stand, the electronic control system and the Faraday’s cage.
click the picture to enlarge
The probe tip is the component fully designed and manufactured by Instytut Fotonowy Sp. z o.o. It provides:
The tip oscillations are generated with an electromagnet.click the picture to enlarge
The Kelvin Probe set includes two types of sample stands:
The whole measurement instrument is covered with Faraday cage which shields the system from the surroundings. The grounding socket is situated on the cage.click the picture to enlarge
The following specification may be changed in terms of further process of appliance development.
|Voltage range||-5 V .. 5 V|
|Voltage measurement nominal resolution||0.15 mV|
|Measurement technology||2-channel lock-in amplifier|
|Sample holder||motorized translation stage X-Y,
|Sample stand||stand for sample layer/ stand for solid state sample|
|Range of stage movement||5 cm x 5 cm|
|Min sample move step||1 µm|
|Tip type||Au, mesh, dia. 2.5 mm|
|Tip Z positioning||motorized Z stage|
|Positioning with respect to a sample||light barrier|
|Tip Z positioning resolution||10 µm|
|Spectral range for wave guides||200 nm .. 2000 nm (depending on a waveguide)|
|Liquid waveguides selection (Lumatec)|
|Auxiliary sensors||humidity and temperature|
|Internal Faraday cage illumination||white LED|
|X-Y positioning aid||laser sample placement indicator|
|PC connectivity||USB 2.0|
|Size||40 x 40 x 45 cm|
PTFE on alluminium foil – Electric potential from the surface charge of the samplekliknij obrazek, aby powiększyć