How a Diode Works: Semiconductor Silicon Circuit

[Jack]

How does a diode work?

Or more precicely how does a semiconductor such as silicon only allow current to flow one way around a circuit?

 

[Janus]

The silicon isn't pure, it is "doped" by adding a small impurity, By carefully choosing what you use to dope the silicon with, you can ened up with two types of material called N or P. Th difference being how many electrons are in the outer shell of the doping material. A diode is made by joining together two sections of N and P material and attaching a wire to each.

If a voltage is applied in one direction All the electrons in the N material are drawn away from the Junction with the P material. Since the P material doesn't have any free electrons to "give" to the N material, no current flows.

If you reverse the voltage direction, the free electrons will flow from the N material into The P material (which readily accepts them). These electrons are replaced by new electrons entering through the wire attached to the N material, while the wire attached to the P material draws electrons out(making room for more electrons from the N material). A current flows.

This is somewhat of a rough explanation, but it should give you the basic idea.

 

[ravenprp]

A diode is a semiconductor device that allows current to flow in only one direction. It is made up of a p-n junction, which is the interface between a p-type semiconductor (excess of positive charge carriers) and an n-type semiconductor (excess of negative charge carriers). This junction creates a depletion region where there are no free charge carriers.

When a diode is forward biased, meaning the positive terminal of the battery is connected to the p-type material and the negative terminal to the n-type material, the depletion region shrinks and allows the flow of current. This is because the positive terminal of the battery attracts the negative charge carriers in the n-type material and the negative terminal attracts the positive charge carriers in the p-type material, creating a path for current to flow.

On the other hand, when a diode is reverse biased, meaning the positive terminal of the battery is connected to the n-type material and the negative terminal to the p-type material, the depletion region widens and prevents the flow of current. This is because the positive terminal of the battery repels the positive charge carriers in the p-type material and the negative terminal repels the negative charge carriers in the n-type material, creating a barrier for current to flow.

In a semiconductor like silicon, the movement of charge carriers is controlled by the presence or absence of impurities in the material. These impurities, also known as dopants, can be added during the manufacturing process to create either a p-type or n-type material. This allows the semiconductor to have different properties and enables the creation of a p-n junction, which is essential for the functioning of a diode.

In summary, a diode works by utilizing the properties of a p-n junction in a semiconductor material. This allows it to act as a one-way valve for current, only allowing it to flow in one direction and blocking it in the other. Its simple yet crucial design makes it a fundamental component in many electronic circuits and devices.