What is Diode?

Basically, solid-state diode is a semiconductor device (consisting of two electrodes) that permits the flow of current in only one direction. It is simplest electronic component of semiconductors family.

Diode is an electronic device that allows the flow of current in only one direction. Generally, diodes are classified into three categories:  a) the signal diode, b) the rectifiers diode, and the regulator diode. When they are used in signal circuits, they are called “signal diodes”. When they are used for the conversion of AC to DC they are called “rectifiers”. When they used for controlling voltage they are called “regulator diodes”. Zener diodes are especially designed for controlling voltage.

        A solid-state diode has generally two electrodes namely, cathode and anode. The arrow-head represents the anode, whereas, the bar signifies the cathode. The arrow and bar are standard symbols for a semiconductor diode showing the direction of hole current. Generally, the arrow and bar are marked on the diode. In some cases, a dot or band at one end indicates the cathode side. Sometimes, a positive (+) mark at the cathode side shows that this is the terminal for positive in the direction of “conventional ” current flow in the diode when it is forward biased. Conventional current flow is from the positive terminal of the voltage source, through the load, to the negative terminal of the voltage-producing device. For those who are accustomed in terms of the electrons flow, the direction of conduction must be assumed to be against the arrow.