How Semiconductor Diodes Work

Function

Semiconductor diodes are electronic components that are often compared to hydraulic "check valves" in terms of function. This is because semiconductor diodes allow current to flow only one way. For example in an alternating current circuit, current can reverse direction and flow "backwards" through a circuit. Semiconductor diodes prevent this back flow and keep the current flowing in the same direction.

Mechanics

Semiconductor diodes are defined as "two element semiconductor devices that make use of rectifying properties of a PN junction." Simplified that means that semiconductor diodes are made up of two different types of semiconductor. One type is called a "P-type." The other is "N-type." Each of these types of material is crystalline with a different type of impurity atoms added into them. The area where the two semiconductor materials meet is called a "junction."

Semiconductor Diodes in Action

Diodes have two parts--a cathode and an anode. The anode is the part of the diode which accepts incoming currents, while the cathode is the part that allow the release of the currents outward. The cathode end of the diode will be marked with a stripe. The site All About Circuits gives one good illustration of how a semiconductor diode works. If a semiconductor diode is placed in typical DC circuit with a light bulb, the diode will allow the current to flow from the battery to the light bulb as long as the anode (N-type) side is facing the battery. This is called "forward biased." If the diode is turned the opposite direction so that the P-type material (the cathode) is facing the battery, it will block the flow of current. This is called "reverse bias."

Resources

• All About Circuits for more about diodes