# PN junction charge difference

• messysmurf
In summary, the depletion region in a PN junction creates an electrostatic field that prevents the flow of current between the P and N doped sides. This means that connecting an external metal wire from one side to the other will not cause current flow, as the field will still prevent hole and electron movement.

#### messysmurf

In a PN junction, if the P doped side becomes negatively charged with respect to the N doped side, does this mean that the application of an external metal wire, from the P side to the N side would cause current flow in that wire?

Gien that the depletion region can be readily made at least 0.1 mm in size, and integrated circuitry can be made much, much smaller. Could a wire be periodically switched to connect the regions, allowing for regeneration of charge when the wire is open?

Hi M-smurf
I suppose what you are considering is that the depletion zone similar to a battery or charged capacitor and that it should be possible to short circuit the depletion zone or attempt to grab some energy from it externally.

The holes from the P-side combine with the electrons from the n side leaving an area that has no charge carriers. Subsequentially, outside the depletion zone, the p side has an area of negatively charges ions, and the n side has an area of positively charge ions. At some point the electrostatic field set up by these ions becomes great emough to prevent any more electron or hole movement.

If you connect a wire directly between the 2 sides, the electrostatic field will still prevent hole and electron migration even though there is now a "short circuit path available. Whether an electron from the n side tries to take the path to the p side either throough the depletion zone or through the wire, it will still be subject to the negative part of the field from the negative ions on the p side. And vice versa for a hole from p to n side.

hope that helps.

## 1. What is a PN junction charge difference?

A PN junction charge difference is the difference in charge carriers between the P-type and N-type semiconductor materials that make up the junction. This difference in charge creates an electric field that allows for the flow of current.

## 2. How is the PN junction charge difference created?

The PN junction charge difference is created through a process called doping, where impurities are intentionally added to the semiconductor materials. In the P-type material, impurities with fewer valence electrons than the base material (such as boron) are added, creating a positively charged material. In the N-type material, impurities with more valence electrons (such as phosphorus) are added, creating a negatively charged material.

## 3. What is the role of the PN junction charge difference in electronic devices?

The PN junction charge difference is crucial in electronic devices as it allows for the control and flow of current. By applying a voltage to the PN junction, the charge difference can be manipulated, allowing for the creation of diodes, transistors, and other electronic components.

## 4. How does the PN junction charge difference affect the behavior of a diode?

In a diode, the PN junction charge difference causes the flow of current to be restricted to one direction. When a forward voltage is applied, the charge difference decreases, allowing current to flow. However, when a reverse voltage is applied, the charge difference increases, blocking the flow of current.

## 5. Can the PN junction charge difference be changed?

Yes, the PN junction charge difference can be changed by varying the amount of doping in the semiconductor materials or by applying a voltage to the junction. This allows for the creation of different types of electronic devices with varying current flow and behavior.