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New UHV Kelvin Probe for Work Function Measurements
The Kelvin Probe is a non-contact, non-destructive measurement device used to investigate properties of materials. It is based on a vibrating capacitor and measures the work function difference, or for non-metals, the surface potential, between a conducting specimen and a vibrating tip. The Work Function is an extremely sensitive indicator of surface condition and is affected by adsorbed or evaporated layers, surface reconstruction, surface charging, oxide layer imperfections, surface and bulk contamination, etc.
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UHV
Scanning Kelvin Probe
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Ambient Scanning
Kelvin Probe System
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Digital control of all probe parameters.
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Voice coil driver mechanism.
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Very high work function resolution using 'off null' detection.
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Significantly reduced driver talkover noise compared with Piezoelectric drivers.
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An auto tracking facility which is essential for repeatable measurements of the work function and surface potential.
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Tip suspended above sample.
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Tip diameter from 2mm to 10mm.
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Easy interchange of tip.
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Tip amplitude is user configurable from microns to mm.
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Variety of mounting geometry (30°, 45° etc.) available
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Port Flange is 2.75" OD (CF)
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Flange to sample length tailored to suit client needs.
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Manual translation: 50.8mm (2 inches) or 101.6mm (4 inches).
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Motor translation upon request.
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Vacuum Compatibility < 4 x 10-11 Torr
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The
original apparatus of Lord Kelvin.
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Cr deposited on
Si(100)
Sample courtesy of: Dr. Bert Lagel Department of Nanotechnology University of South Florida. |
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100nm
ITO on glass
Sample courtesy of: Dr. Dmitry Poplavskyy OSRAM Opto Semiconductors Inc. |
100nm
PEDOT:PSS
Sample courtesy of: Dr. Dmitry Poplavskyy OSRAM Opto Semiconductors Inc. |
Kelvin Probe System Description:
The non-scanning ambient Kelvin probe system includes ambient head unit and optical mounts based upon a 25 x 25 (cm) optical breadboard with the head positioned vertical above the sample holder. The head can be manually translated 25.4 mm normal to the specimen. The specimen (or head unit) can be optionally mounted on a manual (x,y) table. The associated digital electronic unit powers the head unit and provides an interface between the head unit and the PCU data acquisition system mounted in the IBM compatible PC. One PCI slot is required. We can supply the PC if required.
The head stage features
a built in pre amplifier ensuring high signal levels, the system, also features
the 'Baikie off-null' method of performing high resolution, repeatable work
function measurements using a programmed tip potential scan and automatic control
of the tip to sample mean spacing. This significantly reduces drift and the
effects of stray capacity.
User digital control of
probe amplitude, probe frequency, mean spacing, tip potential.
Automatic measurement of Kelvin probe signal, work function, signal and work
function averaging, automatic control of tip to sample mean spacing. Export
of data to excel compatible spreadsheets.
In additional to those specified above, user control of motorized translators allowing custom (X,Y) scans permitting high resolution work function topographies up to 50 mm per side. Software features tip tracking control during scanning and real-time 3D reporting of sample work function and sample height topographies. Export of data to excel compatible spreadsheets.