Help with my Van der Pauw (resistance) measurements please

[mahya137]

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

 

[berkeman]

Welcome to PF.

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

 

[phyzguy]

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?