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Electrical semiconductor characterization
Luminescence dating, research, dosimetry and more
Contamination monitor, beta-aerosol monitor, dose rate meter and more
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...
for quality control of bifacial PERC/PERC+ solar cells and more
portable in field PID tester for solar modules
user friendly and advanced operating software
The PIDcon devices are designed to investigate the PID susceptibility for production monitoring of solar cells as well as tests...
Learn more about the reasons for PID and the how the susceptibility of solar cells, mini modules and encapsulation materials can...
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.
Robust XRD equipment for fully automated in-line testing & alignment
for blanks, wafers & bars (AT, SC, TF, etc.)
three generations of X-ray engineers
in industrial production, R&D and more
discover the most convenient way of measuring orientation of single crystals
Our quality management system is an integrated process-oriented system with ISO 9001 certification.
For a lot of applications a well passivated surface is necessary e.g. in solar cells. With MDPmap and MDPingot it is possible to investigate the quality and homogeneity of the passivation with a high resolution.
The measured or effective lifetime consists of the bulk lifetime and the surface lifetime, via:
That‘s why the surface properties, especially the surface recombination velocity S, has a huge influence on the measured lifetime. This can be used to investigate the surface properties of a sample. Thermal silicon oxide or SiNx are often used to passivate the surface of Cz- , Fz- or mc-Si, which means that the surface recombination velocity is minimized strongly. The homogeneity of this passivation layer can be investigated by lifetime measurements. The aim is to measure the homogeneity of a passivation layer with a high resolution.
With MDPmap, MDPingot or MDPinline it is possible to investigate the homogeneity of a passivation layer with a very high resolution (only limited by the diffusion length of the carriers), which is exemplary shown in figure 1. Especially in high quality material with a high bulk lifetime the surface recombination is very dominant, so that every difference in a lifetime map has its origin in passivation inhomogeneity.
By a measurement with different wavelength or different sample thickness even a good estimation of the surface recombination velocity can be made. If the sample quality is very high as in FZ-Si the surface recombination velocity can be determined from the measured lifetime by assuming that the bulk lifetime is only dependent on the Auger recombination.
MDPmap, MDPingot or MDPinline enables to measure the homogeneity of a passivation layer with a very high resolution even inline. With this an optimization of the passivation process is possible.
To approximate the bulk lifetime from the measured lifetime on unpassivated bricks, the following equation is used:
With d - sample thickness
α - 1/penetration depth
α = a/s (s – skin depth of the microwave; a – empiric factor, which was determined from comparison with passivated wafers from the same bricks)
L – diffusion length
D – diffusion coefficient
S – surface recombination velocity for as cut surface (S = 2.0e+5)
For further information please read:
 J. Schmidt, Thesis, Universität Hannover, 1998