# How do I prove that Vbi in a diode (P-N junction) exists?

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#### sharas

##### Member level 4
If I try to measure the built in potential in a P-N junction in equlibireuim, I wil measure 0. This is explained because of the potential barier at the schotkey diode (electrode-semiconductor junction).
How can I convince myself the there really is an internal electic field inside the semiconductor and it's not just a story?

Sharas

#### aryajur

Re: How do I prove that Vbi in a diode (P-N junction) exists

The built in potential is the limit of the forward bias potential that can be applied to a diode, since the current increases exponentially as you get close to it, the current becomes huge, so the knee voltage in the diode is an indication that a built in voltage exists.
The fact that calculations which take the built in potential into account do give accurate answers suggests that it really exists.
In a solar cell the when exposed to light there is a voltage across the terminals for no current. The open circuit voltage will again have the built in potential as the limit. Its just because the entire IV curve shifts down.
Well none of them are really convincing. One thing I thought was that if there is a small potential difference just at the junction then the electron affinity or the semiconductor work function at the 2 sides of an abrubt junction close to it should be different for the semiconductor. I don't know if that can be verified experimentally.

Points: 2