question about PN junctions

[vivi-d]

Just wondering... if you had piece of N doped silicon (or P doped) would it be a conductor by itself?

[Doctorandus_P]

Silicon is a semi-conductor, which means that it conducts significantly less then "the average metal", but much more then insulators.

https://en.wikipedia.org/wiki/Silicon

Doping silicon is typically in the single digit ppm range or less, and this changes very little to it's overall conductivity.
It is only the interaction between the N and P boundary layer that strange things happen.
There is also a similar boundary layer between a metal and doped silicon, that is called a skottky diode.

But the bulk material itself is just slightly resistive regardless of the small amount of doping.

** Edit **
Oops, I: )(*&^%$#@!
As written below...
A "clean" semi conductor, conducts a bit, and adding doping adds charge carriers, and thus indeed increases conductivity and decreases resistance.
So I agree with the kind peaple below and  I wrote down a bit of a brain fart here earlier.
I'm sorry for that.

[vivi-d]

Thanks! That clears things up

[magic]

Doping increases the amount of available charge carriers (free electrons or holes) and thus increases conductivity and decreases resistance.

If you don't know whom to believe, see the chapter on resistors here, for example.

[MathWizard]

Not long after they classified semi-conductors, they noticed they can be light sensitive too, so the material can conduct more or less, depending on the light level. The incoming photons can knock more electrons up in energy, into the conduction band, as they call it.
https://www.youtube.com/watch?v=a3PXVakobDU&ab_channel=MrSmith%27sPhysicsonline

[Kleinstein]

The doping has quite some effect on the conductivity. The doping level is often given by the conductivity, not the actual concentrations.

A somewhat tricky part is making the contracts. Because of surface oxide and contaminations at the surface one can not just put the DMM probles to the surface and expect a good contact. One may end up with a diode like contract.

[vivi-d]

I work on a bed of nails test systems, it seems contact is half of my job lol

[TimFox]

A detail about charge carriers:
If you look up the Hall Effect, it is interesting that the polarity of the voltage measured in the direction perpendicular to both the applied field and the current flow depends on the polarity of the charge carriers:  positive holes or negative electrons.

[hamster_nz]

A detail about charge carriers:
If you look up the Hall Effect, it is interesting that the polarity of the voltage measured in the direction perpendicular to both the applied field and the current flow depends on the polarity of the charge carriers:  positive holes or negative electrons.

Are you coming here looking for trouble Tim, with all this talking of 'holes' carrying charge?

[TimFox]

Back at university, I measured such things in an instructional lab.
It's very revealing to see net mobility of these charge carriers as a function of temperature.