Αισθητήρας Kelvin (Kelvin Probe)
Πλήρης Αισθητήρας Kelvin: Μετρά με ακρίβεια τη Διαφορά Δυναμικού Επαφής (CPD) του δείγματος και της ακίδας ξεχωριστά, εξαλείφοντας την ασάφεια στη μέτρηση.
Complete Kelvin Probe
The Complete Kelvin Probe is an invention by Instytut Fotonowy that addresses a 150-year-old limitation of traditional Kelvin Probes: when a change in Contact Potential Difference (CPD) is observed, it’s unclear whether the change originates from the sample’s Work Function (WF) or from the WF of the probe tip.
The Complete Kelvin Probe is the ultimate CPD measurement device. It performs all the functions of conventional Kelvin Probes but adds the unique capability to measure:
The CPD of a sample with respect to the ground
The CPD of the tip with respect to the ground
This feature allows users to clearly distinguish the contributions to the sample-tip CPD from both the sample and the tip
Complete Kelvin Probe at Work
Sample-Tip CPD
Sample-Tip Contact Potential Difference (blue) with recorded ambient air temperature (green) and relative humidity (orange):
Sample-ground CPD
Sample-ground Contact Potential Difference (red) with recorded ambient air temperature (green) and relative humidity (orange). It represents only a small fraction of the sample-tip variation.
Tip-ground CPD
Tip-ground Contact Potential Difference (gold) with recorded ambient air temperature (green) and relative humidity (orange). It shows that most of the CPD change is due to the change on the tip’s surface.
Kelvin Probe Modules
The Kelvin Probe set consists of:
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Controller unit
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Kelvin Probe instrument with the Probe Tip
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Faraday Cage
The Kelvin Probe instrument is equipped with:
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Protective bay to park the Probe Tip after experiment
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Laser pointer to indicate the area directly
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Light source that helps to handle the sample when the instrument is covered with the Faraday Cage
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Laser barrier to precisely detect the Probe Tip distance to the sample
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Golden Probe Tip
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Sample holder
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Motorized XY Table
Probe Tip
The most important part of the Kelvin Probe instrument is the Probe Tip. The reference electrode is made of Au mesh of 2.5 mm in diameter. It provides high signal to noise ratio, even from a distance of 0.5 mm above the sample. Thus, it does not matter if the examined sample surface is rough or polished. The tip oscillations are generated with an electromagnet.
The Probe Tip is the component fully designed and manufactured by Instytut Fotonowy.
Specifications
General:
Weight: 15 kg
Size: 40x40x45 cm
PC connectivity: USB 2.0
Power supply: 230 V, 50 Hz or 115 V, 60 Hz
Measurement technique: 2-channel lock-in-amplifier
Laser barrier to automatically detect the substrate and prevent the tip from running into the sample
Auxiliary sensors: humidity, temperature
Small lamp
Laser pointer for examined point of the surface indication
Sample holders:
– Freely shaped solid state with top contact holder
– Bottom contact holder
– Electrochemical holder
Faraday Cage:
Standard / gas-tight with inert gas flow system
Measurement unit:
Bias voltage range: -5 ÷ 5 V
Voltage measurement resolution: 0.15 mV
Current ranges: 300 nA, 30 nA, 3 nA, 300 pA
Probe Tip:
Probe Tip type: Au mesh, 2.5 mm in diameter
Tip positioning resolution in vertical axis: 20 µm
Automated resonance frequency scanning
Adjustable oscillation amplitude
Automated removal of the parasitic current of the tip
Partial transparency for the light
Typical CPD measurement distance: 0.2 – 1 mm
XY Table:
Motorized, controlled via software
Size: 50 x 50 mm
Movement range: 50 x 50 mm
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