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Post by suhridkhan on Jun 3, 2019 18:03:10 GMT -5
We have is a Model 8425 DC Hall system with CRX-VF probe station.
Attempting to measure a high resistivity (10^5 ohm-cm), and possibly low mobility thin film material. 1cm2 square samples with contacts on each corner.
My question is - what does it mean when the carrier type is different for Geometry C and D? What does these geometries actually mean? Can someone direct me to some documentations regarding this?
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Post by Lake Shore Jeff L on Jun 4, 2019 15:02:46 GMT -5
Geometry C and D refer to two different way to connect the current source and voltmeter to your sample. For a hall measurement the current source is connect on one diagonal of the sample and the voltmeter is connect to the other diagonal. However, if you interchange the current source and voltmeter this is also a valid measurement. These two measurements a called Geometry C and Geometry D. If the sample is idea, these two measurements are equal. One reason why you could be getting different carrier type in the two geometries is that the mobility of your sample is too low for a DC field measurement. When the mobility of your samples is below about 10 cm 2/(V s), the DC measurement becomes very difficult. Here is a link to our white paper on AC field Hall measurements. The AC field option is not available on the superconducting magnet 8425 system, but the white paper describes the problems of measuring low mobility samples with DC field Hall. Let me know if yo have any questions. |
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