diode

A device with a structure that combines two semiconductors: P-type and N-type. It has two electrodes: an anode on the P-side and a 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 bias. 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, preventing current flow—this is called reverse bias. Utilizing the property of this diode that allows current to flow in only one direction, it is widely used in switching power supply circuits, starting with rectifier circuits, and is one of the fundamental and important components. In addition, when a high reverse voltage is applied, current suddenly begins to flow at a certain point. This phenomenon is called breakdown (Zener effect), and the voltage at this point is called the Zener voltage. A special diode that uses this breakdown phenomenon to allow current to flow in the reverse direction is called a Zener diode.