is the postive voltage to PN junction that allow the current to pass through it?

[TicTek]

Hi folks,

I was led to confusion by an experienced electronic engineer who told me that for a diode (PN Junction), it is not only that if apply a voltage across its terminal that will make it conduct but also if we force a current into it, it will generate a differential voltage on its terminal!!

So, here I am confused of cause/effect. Is the voltage that causes the current, or also a forced current causes a voltage?
All books I read they specify applied voltage leads to a diode conducting current!!

 

[betwixt]

'Forcing' current doesn't sound right, it will conduct a current when sufficient voltage is applied across the terminals. I think the confusion may be that when a PN junction is conducting (passing a current), there will be a voltage dropped across it, much as there would be if a current passed through a resistor. Different junction materials and particular device types may result in different voltages but unlike a resistor, the voltage stays relatively constant as the current changes.

Brian.

 

[KlausST]

Hi,

there are (constant) voltage sources ... and (constant) current sources.
Both feed the "value" to a load.

For a (constant) voltage source ... no load is needed. The voltage exists and can be measured and regulated.

This is different with a current source. It needs a load for a current to flow.
Indeed a constant current source usually regulates the voltage in a way that the expected current will flow.

***
Now what your electronics engineer means (most probably):
You can apply a constant current to a PN ... and then you can measure a voltage across the PN.
But for sure - as said above - it needs a voltage for a current to flow.

***
For sure one can bring up extreme examples where this seems not to be true.
Like a ring of supra conductor ... when an external magnetic field is applied.
There surely will be current flow within the supra conductor ... but is there also a voltage, too?

Klaus

 

[danadakk]

Basic diode operation :

https://www.youtube.com/results?search_query=diodes+explained

https://www.phy.olemiss.edu/~cremaldi/PHYS321/Chapter5-DiodeBasics.pdf

https://www.asc.ohio-state.edu/gan.1/teaching/spring17/Lec5.pdf

Regards, Dana.

 

[TicTek]

Basic diode operation :

https://www.youtube.com/results?search_query=diodes+explained

https://www.phy.olemiss.edu/~cremaldi/PHYS321/Chapter5-DiodeBasics.pdf

https://www.asc.ohio-state.edu/gan.1/teaching/spring17/Lec5.pdf

Regards, Dana.

Thanks