Help with my Van der Pauw (resistance) measurements please

  • Thread starter mahya137
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In summary, the request seeks assistance with Van der Pauw resistance measurements, highlighting challenges experienced in the experimental setup or data interpretation. The focus is on obtaining guidance for accurate measurement techniques and addressing potential issues that could affect the reliability of the results.
  • #1
mahya137
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0
Hi,
I am doing some vander pauw measurement and when I change the current from 1microA to 1nanoA, I get almost the same voltage meaning different resistivity. I would appreciate if you help me with this
 
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  • #2
Welcome to PF.

mahya137 said:
Hi,
I am doing some vander pauw measurement and when I change the current from 1microA to 1nanoA, I get almost the same voltage meaning different resistivity. I would appreciate if you help me with this
Can you give more details of your sample and probe placements? What instrument(s) are you using to make these measurements? What is the sample material, and what are its dimensions?

https://en.wikipedia.org/wiki/Van_der_Pauw_method

1697133489138.png
 
  • #3
1 nanoA is almost certainly not enough current to get a measurable voltage. 1 microA may not be enough current also. In addition to the things @berkeman mentioned, can you tell us the voltage measurements you are seeing?
 

FAQ: Help with my Van der Pauw (resistance) measurements please

How do I ensure good electrical contact in Van der Pauw measurements?

To ensure good electrical contact, you should use a conductive adhesive or solder to attach your contacts to the sample. Make sure the contacts are clean and free from oxidation. Additionally, the contacts should be small compared to the sample size to avoid affecting the measurement accuracy.

How do I correct for temperature variations in Van der Pauw measurements?

Temperature variations can significantly affect resistance measurements. To correct for this, you should perform your measurements in a temperature-controlled environment. Use a thermometer to monitor the sample's temperature and apply temperature correction factors if necessary. Additionally, allow the sample to reach thermal equilibrium before taking measurements.

What is the best way to deal with contact resistance in Van der Pauw measurements?

Contact resistance can be minimized by ensuring good quality contacts, as mentioned earlier. Additionally, you can use a four-point probe method where the current and voltage contacts are separate. This method helps to eliminate the effect of contact resistance on the measurement.

How do I handle asymmetry in the sample shape during Van der Pauw measurements?

Asymmetry in the sample shape can lead to errors in Van der Pauw measurements. To handle this, you can use a correction factor based on the sample geometry. Alternatively, measure the resistance in multiple configurations and average the results to minimize the impact of asymmetry.

Why am I getting inconsistent results in my Van der Pauw measurements?

Inconsistent results can be due to various factors such as poor electrical contacts, temperature fluctuations, sample inhomogeneity, or measurement setup issues. Ensure that your contacts are well-made, maintain a stable temperature, use a homogeneous sample, and double-check your measurement setup for any inconsistencies or errors.

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