Is it possible to measure the resistance of n-Si or p-Si using multimeter?

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Discussion Overview

The discussion revolves around the feasibility of measuring the resistance of n-type and p-type silicon (Si) using a multimeter. Participants explore the principles of resistance measurement, the characteristics of silicon as a semiconductor, and the implications of doping on conductivity.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether a multimeter can provide current to n-type or p-type silicon when measuring resistance, noting the behavior of diodes when connected to different types of silicon.
  • Another participant shares an experience of measuring a piece of silicon that was expected to be an insulator but behaved as a conductor, suggesting the presence of impurities.
  • A different participant acknowledges that while a multimeter can measure resistance, the results may be inaccurate due to voltage drops across the leads and suggests using Kelvin's four-probe method for more accurate measurements.
  • Concerns are raised about the contact quality between the probes and silicon, with a note on the potential for Schottky contacts affecting measurements.
  • One participant asserts that silicon wafers are typically p-type doped, while ingots may have uneven doping, and mentions the presence of impurities in certain silicon samples.

Areas of Agreement / Disagreement

Participants express differing views on the accuracy and feasibility of using a multimeter for measuring resistance in silicon, with no consensus reached on the best method or the implications of doping on measurement outcomes.

Contextual Notes

Limitations include potential inaccuracies in multimeter readings due to contact resistance and the influence of doping levels on the conductivity of silicon samples. The discussion does not resolve the conditions under which accurate measurements can be obtained.

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As the title says, is it possible? I was thinking that in order for the multimeter to measure resistance, it first provides current and checks the voltage, and then by ohm's law gets the resistance.

But would it even be possible to provide current to n-type Si bar or p-type Si bar? I know that in the diode, when the positive and negative leads are connected to p-type and n-type respectively, you can provide current. But what's going to happen if both positive and negative are connected to just n-type or just p-type?
 
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Yes, you can do that.

I tested a piece of Silicon which was supposed to be just elemental Silicon and should have been an insulator.

However, it was quite a good conductor.

Presumably it had been sourced from a semiconductor supplier and had deliberate impurities in it. I could not tell if it was N-type or P-type.
 
Yes a multimeter will do, but the result will be inaccurate. The voltage drop across the lead will also be included in measurement. Better use Kelvin's four probe method with corrections for probe placements, for much accurate result.

Make sure you solder the probes with Si to get good contact. Usually metal pressed against Si will have some small discontinuity at the interface sufficient to introduce high resistance. Also check whether the probe material produces Schottky contact with n and p silicon.

You can connect the diode in reverse and still get a current. only thing is that the current will be tiny. Well its a property of the diode. But your material is purely resistive. Thus you can connect any way you chose.
 
@ vk6kro - If you have a Si wafer it will be almost always evenly p type doped. It won't be intrinsic, or semi-insulating unless you're using GaAs wafer. If you have Si ingot it will be non evenly doped. The ingots and wafers are doped deliberately. However if you have MGS piece of Si it will have many unwanted impurity, defects and stuffs.
 

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