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Upgrading an existing Hall Effect mesurement system

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amitabhas75
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Joined: November 26th, 2013, 1:40 pm
Country: United States

Upgrading an existing Hall Effect mesurement system

Post by amitabhas75 » November 26th, 2013, 1:43 pm

We have made a Hall-effect measuring instrument for use on thin films using the following :--
1. Keithley 225 current source
2. Keithley 181 nanovoltmeter
3. Sample holder
4. An electromagnet capable of producing 1.4 Tesla field

When using the range below 2 V in the 181 nanovoltmeter, the numbers fluctuate quite a bit. I would like to have a fairly steady number so that I can have confidence in the numbers. Is there any way to fix this? Or can we use a simple DMM instead as mentioned in the document for the 7065 Hall effect card?

At the present we manually switch the banana plugs / jacks when switching configurations during measuremnt. I have read the Hall-effect measurement whitepaper by Robert Greeen of Keithley. There the author presents the use of the 7065 Hall-effect card inserted into a Keithley 7001 switch system.

I want to know how to clean up the measured signal so that we can have a steady value when making measurements in the 20-200 mV range. Our samples are typically 1cm - 1.5 cm square, 1 micron thick, and have a resisitivity of 0.5-2 ohm-cm. At this point it seems that we can either
A) Have our current one calibrated (or fixed)
B) Buy a new voltmeter
C) Buy and integrate the Hall-effect card with the 7001 switching system.

Please let me know what you would suggest.

Dale C
Keithley Applications
Keithley Applications
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Joined: June 10th, 2010, 6:22 am
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Re: Upgrading an existing Hall Effect mesurement system

Post by Dale C » December 4th, 2013, 1:40 pm

The nanovoltmeter is not required unless measuring low resistivity samples.
Any standard DMM should dothe job for most applications.
The Model 181 has been obsoleter for about 20 years and is no longer serviced.
The Model 7001 switch system with the Model 7065 Hall effect card would help if you want to perform several different connections to the sample automatically. The 7065 is a four x five matrix with four electrometer grade buffer amplifiers. This allows measurements on extremley high resistivity samples up to 1T ohms or so.
if you have a sample that is below say, 1G ohm then most matrix cards would suffice. Model 7012 comes to mind.
Here is a list of equipment that would represent the present Hall Effect system from Keithley.
Model 7001 switch system
Model 7065 Hall effect Scanner card
Model 6220 current source
Model 2182A nanovoltmeter
Model 6485 -
Here is a link to a video describing all of this...
http://www.keithley.com/centralized_dis ... etid=55820

amitabhas75
Posts: 2
Joined: November 26th, 2013, 1:40 pm
Country: United States

Re: Upgrading an existing Hall Effect mesurement system

Post by amitabhas75 » December 4th, 2013, 1:52 pm

Dear Dale,
Thanks for your suggestions.
Regards,
Ami

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