Diode

A device with a structure formed by combining two types of semiconductors: P-type and N-type. It has two electrodes: the anode on the P side and the cathode on the N side. When a positive voltage is applied to the anode and a negative voltage to the cathode, current flows from the P side to the N side—this direction is called forward direction. Conversely, when a negative voltage is applied to the anode and a positive voltage to the cathode, a depletion layer forms at the PN junction and no current flows; this direction is called reverse direction. This property of the diode, allowing current to flow only in one direction, is widely used in switching power supply circuits, especially in rectifier circuits. It is one of the most basic and important components. Additionally, when a high reverse voltage is applied, current suddenly begins to flow at a specific value. This phenomenon is called breakdown (Zener effect), and the voltage at that point is called the Zener voltage. A special type of diode that uses this breakdown phenomenon to allow current to flow in the reverse direction is called a Zener diode.