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Work function differences

by shallowbay
Tags: differences, function, work
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Mar29-13, 08:11 PM
P: 8

I posted this in the "General physics" section as I didn't see the Solid State part of this section.

I am quite confused here. So, I know that if you take any number of materials and place them in series the contact potentials subtract off so that the measured result is simply the difference between the first and last material.

I also know that in a pn junction this is the reason you cannot measure the built-in potential.

However, I was told that one should be able to theoretically measure the work function difference between two metals with different Fermi levels that have not come in contact and thus have not come to an equilibrium Fermi level, using some sort of voltmeter.

How could this be without a Kelvin Probe to measure each one individually?

Is this sensical? How might it be possible? Any comments?

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Mar29-13, 08:14 PM
P: 19
I know you can deduce the work function using X-ray Photoelectron Spectroscopy, but that has nothing to do with voltmeters.

Mar29-13, 08:25 PM
P: 8
And it certainly can't be a normal voltmeter as the contact potentials stop you from measuring it that way, but supposedly it is theoretically possible to measure this potential in some electrically based manner as it's an electrochemical potential difference.

I just can't see it without measuring tunnel current or charge based measurements.

Mar29-13, 08:36 PM
P: 19
Work function differences

Yeah, I'm picturing something like a wire with a resistor connecting the two materials.

As electrons flow from one to another the current goes through the resistor and V=IR so you could get the voltage from resistive heating or something.

Again though, like you said, that's based on current measurement. I'll stop suggesting dumb ideas until somebody more knowledgeable comes along lol

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