PN Junction Question - Current

In summary, a coil around the N terminal of a P/N junction creates a B field, which induces a current in the Lz direction. This current doesn't go anywhere, as the charge carriers are mobile before a potential is applied.
  • #1
K.J.Healey
626
0
I guess my most general question would be:

Given a P/N junction. Let's say two circular discs, one P one N. There obviously exists some Vgap, and applying some voltage across it excites the electrons, then it emits light (very basic LED or something).

Now, what if you took a piece of wire, and coiled it, and put it around the diode. Let's say for arguments sake you theoretically only put the coil around the N part.

Now you run a current through the coil. This creates a B field in the +-Z direction for the N part, which, since semiconducting, creates a current in the Lz direction (loop about the Z axis). Now this current doesn't really go anywhere, right? It just spins around and around.
What I'm wondering is : Would this induced loop current have ANY effect on the Vgap energy (the barrier). I'm figuring perhaps there's something due to scattering, or something else.
I have a feeling it would really only change the free electrons, which might change the intensity, but not the energy of the gap.

Can someone tell me?
 
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  • #2
I don't believe it will make any difference since the magnetic field lines are parallel with the normals to the planes of the n-p junction if I'm reading the description correctly. And I take it the current is steady/constant?
 
  • #3
Indeed. Thats what I was wondering. There would be both the current across the junction, as well as a circular current(which was induced by the field). This is purely a hypothetical. I didn't think it would have any effect, but I couldn't reason out why. I guess the fact that the charge carriers are mobile before a potential is applied across the junction doesn't make them and more or less energetic.

Same idea would work if you had a very very long p/n junction and ran a cross current tangential to the junction normal. Don't know if there would be any difference. Their current bands should be the same, dispersion relations the same; I'm not sure why I thought it would do anything. I guess there just seemed to be something where, if the P part has a cross current, wouldn't SOMETHING change?
 

1. What is a PN junction?

A PN junction is a boundary or interface between a P-type semiconductor and an N-type semiconductor. It forms when a P-type semiconductor material (which contains an excess of positive charge carriers, or holes) is brought into contact with an N-type semiconductor material (which contains an excess of negative charge carriers, or electrons).

2. How does a PN junction work?

A PN junction works by creating a depletion region, or a region with no free charge carriers, at the boundary between the P-type and N-type semiconductors. This depletion region acts as a barrier to the flow of electric current. When a voltage is applied across the PN junction, the depletion region becomes smaller and allows current to flow.

3. What is the mechanism behind current flow in a PN junction?

The mechanism behind current flow in a PN junction is known as the diffusion process. When a voltage is applied, the excess electrons from the N-type semiconductor and the excess holes from the P-type semiconductor diffuse across the depletion region, creating a flow of current.

4. How does the direction of current flow in a PN junction change with different bias voltages?

The direction of current flow in a PN junction depends on the direction of the applied bias voltage. In forward bias, where the positive terminal of a battery is connected to the P-type semiconductor and the negative terminal to the N-type semiconductor, current flows from the P-type to the N-type semiconductor. In reverse bias, where the positive terminal is connected to the N-type semiconductor and the negative terminal to the P-type semiconductor, very little current flows due to the widening of the depletion region.

5. What factors affect the current flow in a PN junction?

The current flow in a PN junction is affected by several factors, including the applied voltage, the doping levels of the P-type and N-type semiconductors, and the temperature. A higher applied voltage, a higher doping level, and a higher temperature can increase the current flow in a PN junction.

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