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Mono- and Multi-crystalline wafer lifetime measurement device
State of the art system for topographic electrical characterization of multicrystalline bricks in fabs with high throughput....
Production integrated high speed wafer mapping of carrier lifetime. Single wafer topograms in less than one second a wafer.
Low cost table top lifetime measurement system for characterization of a variety of different silicon samples at different...
Mono- and Multi-crystalline wafer and brick lifetime measurement device
Flexible OEM unit for lifetime measurements at a variety of different samples ranging from mono- to multicrystalline silicon...
Microwave Detected Photo Induced Current Transient Spectroscopy
The minority carrier life time is sensitive for all kinds of electrically active defects in semiconductors and is therefore...
MDP is an advanced technology with a so far unsurpassed combination of sensitivity, speed and resolution for fab and lab...
benchtop PID test for solar wafers and mini-modules
portable in field PID tester for solar modules
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The PIDcon devices are designed to investigate the PID susceptibility for production monitoring of solar cells as well as tests...
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For ultra-fast crystal orientation and rocking curve measurements
Flexible diffractometer for ultra-fast Omega Scan orientation determination
Smart diffractometer for ultra-fast Omega-scan of small samples.
for blanks, wafers & bars (AT, SC, TF, etc.)
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Changes in the conduction type of a multicrystalline brick are frequently observed, due to a high phosphorus concentration in the low quality feedstock. Hence it is very important to detect such changes from p to n conduction with a high resolution, since the n-type material cannot be used.
In the PV industry sometimes also low quality material with a high phosphorous concentration is used. Phosphor has a segregation coefficient of 0.35 and is therefore segregating in the top of the brick (last part that solidifies).There the concentration can be so high, that even changes in the conduction type from p to n can occur. Of course the n-type material cannot be used anymore for the solar cell production. Before the conduction type changes completely to n-conductivity, there is a narrow part of the ingot that is highly compensated and has a very high resistivity. Since resistivity measurements by eddy current are difficult to achieve in high resolution, it is preferable to use the photoconductivity for the detection of such a pn change.
The photoconductivity or signal height depends on the resistivity because the skin depth of the microwave increases with increasing resistivity, so that at high resistivities a larger volume of the sample is measured. This dependency can be used for the pn detection.
With a clever computer algorithm, it is possible to detect the sharp rise in photoconductivity, so that a pn-change can be detected with a resolution of 1 mm (fig.1 and fig.2). This algorithm can be implanted into the software of the MDPingot and MDPingot inline tool.
The MDPingot and MDPingot inline allows to detect pn-changes inline with a resolution of 1mm as demonstrated in figure 1 and 2. With this feature useless n-material can be sorted out as early as possible in the production process.
For more information please read:
 N. Schüler, D. Mittelstrass, K. Dornich, J.R. Niklas, 35th IEEE Photovoltaic Specialists Conference Honululu, (2010) 852-857