With the aid of the Hall-measurement system it is possible to measure carrier concentration and mobility of different kind of samples. In principle there are no limitations about the material of the sample, if only good ohmic contacts can be made and if the resistivity of the sample is not too high. In addition also the magnetoresistance, Hall voltage, sheet resistance and I-V characteristic can be measured. Of course, all mentioned quantities can be measured as a function of magnetic field or/and temperature.
Figure of Hall measurement system.
The Hall measurement system consists of magnet (Magnion Inc. Model H-96), field regulator of magnet (Magnion Inc., Model FFC-4 Field Regulator), cryostat (APD Cryogenics Inc., Helium Compressor Model HC-2D), temperature controller (Scientific Instruments, 9620 Temperature Controller), electrical measurement equipments (2*Keithley 236 Source measurement unit, Keithley 197 A Autoranging DMM and Keitley 7001 Switching system) and computer.
If the measurement is done at room temperature, it takes about 10-20 minutes to measure the sample. The measurement takes longer time, if the measurement is not performed at room temperature. It is due to two matters. First the sample holder is different, when using the cryostat. In practice it means, that the preparations of the sample takes more time and the good contacts are more difficult to fabricate. Second it takes time, when the temperature of sample is changed.
Technical data| From | To | |
| Applied external magnetic field | -1 T | +1 T |
| Temperature range | 10 K | 400 K |
| Sample size (width, length) 1)* | (3mm,3mm) | (11mm,20mm) |
Contact person:
Heikki Holmberg,
Email: heikki.holmberg@hut.fi
Phone number: +358 09 451 4987