Explaining the physical operation of semiconductor diode (pn junction)

Thread starter eng202
Start date Apr 18, 2013
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Diode Junction Physical Pn junction Semiconductor

In summary, a semiconductor diode is made up of two layers of different types of semiconducting materials, creating a pn junction. When a voltage is applied, it creates an electric field that allows current to flow in one direction while blocking it in the other. The depletion region around the pn junction acts as a barrier for current flow and is affected by forward and reverse biasing. The physical operation of a semiconductor diode is important in various electronic devices, such as rectifiers, voltage regulators, and signal modulators.

Apr 18, 2013

eng202

what is it ?
please
explaining the physical operation of semiconductor diode (pn junction).

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Apr 18, 2013

carlgrace

Try wikipedia. It's pretty good for basic semiconductor questions.

Apr 18, 2013

dlgoff

Science Advisor

Gold Member

I like these a lot.

http://hyperphysics.phy-astr.gsu.edu/hbase/solids/semcn.html

http://hyperphysics.phy-astr.gsu.edu/hbase/solids/sselcn.html

1. How does a semiconductor diode work?

A semiconductor diode is made up of two layers of different types of semiconducting materials (usually silicon). The layer with an excess of electrons is called the n-type layer, while the layer with a deficiency of electrons is called the p-type layer. When these two layers are joined together, a pn junction is formed. When a voltage is applied across the pn junction, it creates an electric field that allows current to flow in one direction while blocking it in the other. This is how a semiconductor diode works as a one-way valve for electric current.

2. What is the role of the depletion region in a pn junction?

The depletion region is the area around the pn junction where there are no free charge carriers (electrons or holes) due to the diffusion of electrons and holes from the n-type and p-type layers. This creates a barrier that prevents current from flowing in the reverse direction. In order for current to flow, the applied voltage must be high enough to overcome this barrier.

3. How does the forward biasing of a pn junction affect its operation?

Forward biasing a pn junction means applying a positive voltage to the p-type layer and a negative voltage to the n-type layer. This decreases the width of the depletion region, allowing current to flow more easily in the forward direction. This is the operating mode of a diode when it is conducting current.

4. What happens when a pn junction is reverse biased?

In reverse bias, the applied voltage is in the opposite direction of the depletion region's electric field. This increases the width of the depletion region, making it even more difficult for current to flow in the reverse direction. In this mode, the diode acts as an insulator and does not allow current to pass through.

5. How can the physical operation of a semiconductor diode be applied in electronic devices?

Semiconductor diodes are essential components in many electronic devices such as rectifiers, voltage regulators, and signal modulators. They are used to convert AC to DC, regulate voltage levels, and control the flow of current. The ability of a diode to allow current to flow in only one direction is crucial in many electronic circuits.